CentOS的启动流程

因6和7俩个系列的启动流程有区别,所以我把他们分开来写

linux可看作是内核和根文件系统组成我们把内核单独拿出来总结一下

CentOS6系列启动流程

首先总结一下总体的流程,接下来展开来叙述:POST加电自检 --  MBR(0扇区前446个字节为GRUB第1阶段) -- (在1扇区后存放GRUB第1.5阶段)GRUB(第2阶段)--  加载内核(vmlinuz,initramfs)--  启动第一个进程(init ;/etc/ini/*.conf init 程序的配置文件)-- 读取/etc/inittab文件来决定进入的系统级别 --  执行/etc/rc.d/rc.sysinit脚本来初始化系统 -- 使用/etc/rc.d/rc脚本来根据当前所在的系统级别来读取对应/etc/rc#.d/下的脚本 -- K开头的脚本不启动,S开头的脚本启动,启动顺序按后边跟的数子大小来决定  --  最后执行的脚本/etc/rc.d/rc.local  --  启动/bin/login进程来启动登录程序 ---  OK!

  1. 加载BIOS的硬件信息,获取第一个启动设备
  2. 读取第一个启动设备MBR的引导加载程序(grub)的启动信息
  3. 加载核心操作系统的核心信息,核心开始解压缩,并尝试驱动所有的硬件设备
  4. 核心执行init程序,并获取默认的运行信息
  5. init程序执行/etc/rc.d/rc.sysinit文件
  6. 启动核心的外挂模块
  7. init执行运行的各个批处理文件(scripts)
  8. init执行/etc/rc.d/rc.local
  9. 执行/bin/login程序,等待用户登录
  10. 登录之后开始以Shell控制主机

1、POST

Power-On-Self-Test:加电自检,是BIOS功能的一个主要部分。负责完成对CPU、主板、内存、硬盘子系统、显示子系统等硬件情况的检测。

BIOS:Basic Input and Output System,保存着有关计算机系统最重要的基本输入输出程序,系统信息设置、开机加电自检程序和系统启动自举程序等。

CMOS:保存主板的设置时间等参数,依靠主板上的CMOS纽扣电池。

2、BootLoader

引导加载器,Windows使用的bootLoader是ntloader,只可以引导Windows系统;Linux使用的bootloader早期有LILO(LInux LOader),现在6系列用的GRUB0.97版,7系列使用的是GRUB2。

3、GRUB

grub总共分为三个阶段:

  1. 第1阶段:存放在mbr前446个字节
  2. 第1.5阶段:1.5阶段存放在1-27扇区;由于grub1阶段需要去读取grub2阶段的程序和配置文件,但是grub2阶段的程序存放在磁盘的/boot分区中,想要读取分区中的文件就必须要有驱动文件系统的驱动模块,1.5阶段就是来做这件事的。
  3. 第2阶段:存放在磁盘可的/boot分区上(/boot/grub/),启动时选择内核版本界面,还有配置文件都是由第2阶段负责。

功用:

  1. 提供启动菜单、并提供交互式接口 
  2. 加载用户选择的内核或操作系统 
  3. 为菜单提供了保护机制 

grub的配置文件(/boot/grub/grub.cfg)

default=0  #默认title
timeout=5 #grub菜单选择超时时间
splashimage=(hd0,0)/grub/splash.xpm.gz #grub菜单背景图片
hiddenmenu #隐藏grub选择菜单
password --md5 | ----encrypted  口令 #加密方式和口令,为grub加密防止进如单用户模式修改密码,口令使用下面的命令生成
# grub-md5-crypt  生成MD5的密码
# grub-crypt 生成sha12的密码
title Red Hat Enterprise Linux 6 (2.6.32-642.el6.x86_64)
        root (hd0,0) #指定的是/boot所在磁盘的分区"hd0,0"表示第一块磁盘的第一个分区
        kernel /vmlinuz-2.6.32-642.el6.x86_64 ro root=UUID=e1d36be7-5027-4847-9d80-135ac9fb798e rd_NO_LUKS rd_NO_LVM LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto  KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet #向内核传递的cmdline参数
        initrd /initramfs-2.6.32-642.el6.x86_64.img  #指定initramfs文件的所在路径,注意:(这里的"/"相对的是/boot分区)

如果grub损坏我们可以用下面命令修复

grub-install --root-directory=DIR /dev/DISK 
    --root-directory=DIR:根目录

如果grub配置丢失了怎么办:

在开机的时候会进入grub的命令行接口,但是无法找到内核和ramdisk,所以我们手动指定参数和路径就可以启动系统了。

help: 获取帮助列表 
help KEYWORD: 详细帮助信息 
find (hd#,#)/PATH/TO/SOMEFILE: 
root (hd#,#) 
kernel /PATH/TO/KERNEL_FILE: 设定本次启动时用到的内核文件;额外还可添加许多内核支持使用的cmdline参数
initrd /PATH/TO/INITRAMFS_FILE: 设定为选定的内核提供额外文件的ramdisk 
boot: 引导启动选定的内核

分别指定root(指的是/boot分区),kernel指定内核,initrd指定ramdisk文件,然后boot就可以启动系统了,进入系统后重新编辑/boot/grub.cfg文件来修复问题

4、kernel自身初始化

  1. 探测可识别到的所有硬件设备
  2. 加载硬件驱动程序(借助于ramdisk加载驱动)
  3. 以只读方式挂载根文件系统
  4. 运行用户空间的第一个应用程序:/sbin/init

5、ramdisk

在grub第2阶段的时候只能识别到/boot分区,这个时候内核开始初始化,探测完硬件后开始需要去找根,但是这时还没有驱动程序,所以这个时候需要借助ramdisk来驱动硬件。在CentOS5系列中文件名为/boot/inird,6和7已经改成initramfs。

initramfs中也提供了一个根文件系统,其中包括了硬件必须的驱动,到了这步内核借助这个虚根文件系统来挂载真正的根文件系统。

initramfs文件是在安装系统时按当前的环境来生成的。

如果这个文件损坏了我们也可以使用工具来修复:

# mkinitrd /boot/initramfs-`uname -r`.img `uname -r` 为当前正在使用的内核重新制作ramdisk文件

6、init初始化

init程序启动系统的第一个进程init,它负责创建系统启动后的所有服务进程

init程序的类型:

  • CentOS5.x:SysV
  • CentOS6.x:Upstart
  • CentOS7.x:Systemd

初始化的相关文件:

  • /etc/inittab:定义系统默认的启动级别
id:3:initdefault:
  • /etc/init/control-alt-delete.conf:设定按Ctrl + Alt + Del 是否会重启
start on control-alt-delete
exec /sbin/shutdown -r now "Control-Alt-Delete pressed"
  • /etc/init/tty.conf
  • /etc/init/start-ttys.conf
  • /etc/init/rc.conf
  • /etc/init/prefdm.conf

7、系统级别(CentOS6.x)

  • 0:关机
  • 1:单用户模式(root自动登录), single, 维护模式
  • 2: 多用户模式,启动网络功能,但不会启动NFS;维护模式
  • 3:多用户模式,正常模式;文本界面
  • 4:预留级别;可同3级别
  • 5:多用户模式,正常模式;图形界面
  • 6:重启

init #:切换至#级别

runlevel:查看当前的运行级别和上一运行级别

示例:进入单用户模式

1)在启动过程中看到Booting 。。。的倒计时字样按下esc键

2)按a键修改启动参数,在quiet后加1(单用户模式)

3)按回车键启动,进入单用户模式,可以直接修改root的密码,或者可以修改一些其他服务配置文件错误导致的系统无法进入正常模式的操作。

8、系统初始化脚本(/etc/rc.d/rc.sysinit)

  1. 设置主机名
  2. 设置欢迎信息
  3. 激活udev和selinux
  4. 挂载/etc/fstab文件中定义的文件系统
  5. 检测根文件系统,并以读写方式重新挂载根文件系统
  6. 设置系统时钟
  7. 激活swap设备
  8. 根据/etc/sysctl.conf文件设置内核参数
  9. 激活lvm及software raid设备
  10. 加载额外设备的驱动程序
  11. 清理操作

9、启动服务脚本(/etc/rc.d/rc)

由/etc/rc.d/rc脚本控制服务脚本启动还是非启动

for i in /etc/rc$runlevel.d/S* ; do

    # Check if the subsystem is already up.
    subsys=${i#/etc/rc$runlevel.d/S??}
    [ -f /var/lock/subsys/$subsys ] && continue
    [ -f /var/lock/subsys/$subsys.init ] && continue
    check_runlevel "$i" || continue

    # If we're in confirmation mode, get user confirmation
    if [ "$do_confirm" = "yes" ]; then
        confirm $subsys
        rc=$?
        if [ "$rc" = "1" ]; then
            continue
        elif [ "$rc" = "2" ]; then
            do_confirm="no"
        fi
    fi

    update_boot_stage "$subsys"
    # Bring the subsystem up.
    [ -n "$UPSTART" ] && initctl emit --quiet starting JOB=$subsys
    if [ "$subsys" = "halt" -o "$subsys" = "reboot" ]; then
        export LC_ALL=C
        exec $i start
    fi
    $i start
    [ -n "$UPSTART" ] && initctl emit --quiet started JOB=$subsys
done

rc脚本读取/etc/rc.d/rc#.d/下的所有脚本,以K开头的服务脚本不启动,以S开头的服务脚本启动。

  • K*: K##*:##运行次序;数字越小,越先运行;数字越小的服务,通常为依赖到别的服务
  • S*: S##*:##运行次序;数字越小,越先运行;数字越小的服务,通常为被依赖到的服务

/etc/rc.d/rc#.d/下的所有脚本都是/etc/rc.d/init.d/下的脚本的符号连接,链接名由chkconfig管理。

/etc/rc.d/rc.local:在所有启动脚本执行完成后执行此脚本,可以把不便或不需写为服务脚本放置于/etc/rc.d/init.d/目录,且又想开机时自动运行的命令,可直接放置于/etc/rc.d/rc.local文件中。

所有服务启动完成后启动登录程序(/bin/login)。

CentOS 6 init程序为: upstart, 其配置文件:/etc/inittab, /etc/init/*.conf,配置文件的语法 遵循 upstart配置文件语法格式,和CentOS5不同。

服务管理工具(CentOS6.x)

chkconfig

  • --list 查看
  • --level ##:指定级别,默认为2 3 4 5
  • --add 将脚本加入对应的级别(需要将脚本放到/etc/rc.d/init.d/目录下,并且在脚本开头加上chkconfig:   启动级别   关闭优先级   开启优先级),一般“关闭优先级 + 开启优先级 = 100”
  • --del 删除对应级别脚本

service  服务名  { start | stop | restart }

  • --status-all 查看所有服务的状态

ntsysv:字符界面工具,用来设置开启自启的服务

CentOS7系列启动流程

内核(kernel)

kernel职责:

  进程管理、内存管理、网络管理、驱动程序、文件系统、安全功能 

内核的设计流派分为单内核和微内核:linux内核为单内核流派,把所有的功能都集成于同一个程序;Windows,Solaris系统的内核是微内核设计,每种功能都使用一个单独的子系统来实现,在一个中心框架下协同工作,从理论上来说微内核的设计更为先进。

linux内核的特点:

  1. 模块化:如把文件系统、硬件启动等编译成模块,使用时装载,
  2. 支持内核模块的动态装载和卸载,更灵活

linux的内核组成:

  • /boot/vmlinz-VERSION-release:核心文件
  • ramdisk
    • /boot/initrd-VERSION-release.img(5.x)
    • /boot/initramfs-VERSION-release.img(6.x和7.x)
  • /lib/modules/VERSION-release  :存放模块文件目录

查看内核当前运行的cmdline参数:

[root@rhel6 ~]# cat /proc/cmdline 
ro root=UUID=e1d36be7-5027-4847-9d80-135ac9fb798e rd_NO_LUKS rd_NO_LVM LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16   KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet

内核参数文档:/usr/share/doc/kernel-doc-2.6.32/Documentation/kernel-parameters.txt,需要安装以下包。

                          Kernel Parameters
                          ~~~~~~~~~~~~~~~~~

The following is a consolidated list of the kernel parameters as implemented
(mostly) by the __setup() macro and sorted into English Dictionary order
(defined as ignoring all punctuation and sorting digits before letters in a
case insensitive manner), and with descriptions where known.

Module parameters for loadable modules are specified only as the
parameter name with optional '=' and value as appropriate, such as:

	modprobe usbcore blinkenlights=1

Module parameters for modules that are built into the kernel image
are specified on the kernel command line with the module name plus
'.' plus parameter name, with '=' and value if appropriate, such as:

	usbcore.blinkenlights=1

Hyphens (dashes) and underscores are equivalent in parameter names, so
	log_buf_len=1M print-fatal-signals=1
can also be entered as
	log-buf-len=1M print_fatal_signals=1


This document may not be entirely up to date and comprehensive. The command
"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
module. Loadable modules, after being loaded into the running kernel, also
reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
parameters may be changed at runtime by the command
"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".

The parameters listed below are only valid if certain kernel build options were
enabled and if respective hardware is present. The text in square brackets at
the beginning of each description states the restrictions within which a
parameter is applicable:

	ACPI	ACPI support is enabled.
	AGP	AGP (Accelerated Graphics Port) is enabled.
	ALSA	ALSA sound support is enabled.
	APIC	APIC support is enabled.
	APM	Advanced Power Management support is enabled.
	AVR32	AVR32 architecture is enabled.
	AX25	Appropriate AX.25 support is enabled.
	BLACKFIN Blackfin architecture is enabled.
	EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled
	EFI	EFI Partitioning (GPT) is enabled
	EIDE	EIDE/ATAPI support is enabled.
	DRM	Direct Rendering Management support is enabled.
	DYNAMIC_DEBUG Build in debug messages and enable them at runtime
	FB	The frame buffer device is enabled.
	GCOV	GCOV profiling is enabled.
	HW	Appropriate hardware is enabled.
	IA-64	IA-64 architecture is enabled.
	IMA     Integrity measurement architecture is enabled.
	IOSCHED	More than one I/O scheduler is enabled.
	IP_PNP	IP DHCP, BOOTP, or RARP is enabled.
	ISAPNP	ISA PnP code is enabled.
	ISDN	Appropriate ISDN support is enabled.
	JOY	Appropriate joystick support is enabled.
	KVM	Kernel Virtual Machine support is enabled.
	LIBATA  Libata driver is enabled
	LP	Printer support is enabled.
	LOOP	Loopback device support is enabled.
	M68k	M68k architecture is enabled.
			These options have more detailed description inside of
			Documentation/m68k/kernel-options.txt.
	MCA	MCA bus support is enabled.
	MDA	MDA console support is enabled.
	MOUSE	Appropriate mouse support is enabled.
	MSI	Message Signaled Interrupts (PCI).
	MTD	MTD (Memory Technology Device) support is enabled.
	NET	Appropriate network support is enabled.
	NUMA	NUMA support is enabled.
	NFS	Appropriate NFS support is enabled.
	OSS	OSS sound support is enabled.
	PV_OPS	A paravirtualized kernel is enabled.
	PARIDE	The ParIDE (parallel port IDE) subsystem is enabled.
	PARISC	The PA-RISC architecture is enabled.
	PCI	PCI bus support is enabled.
	PCIE	PCI Express support is enabled.
	PCMCIA	The PCMCIA subsystem is enabled.
	PNP	Plug & Play support is enabled.
	PPC	PowerPC architecture is enabled.
	PPT	Parallel port support is enabled.
	PS2	Appropriate PS/2 support is enabled.
	RAM	RAM disk support is enabled.
	ROOTPLUG The example Root Plug LSM is enabled.
	S390	S390 architecture is enabled.
	SCSI	Appropriate SCSI support is enabled.
			A lot of drivers has their options described inside of
			Documentation/scsi/.
	SECURITY Different security models are enabled.
	SELINUX SELinux support is enabled.
	SERIAL	Serial support is enabled.
	SH	SuperH architecture is enabled.
	SMP	The kernel is an SMP kernel.
	SPARC	Sparc architecture is enabled.
	SWSUSP	Software suspend (hibernation) is enabled.
	SUSPEND	System suspend states are enabled.
	FTRACE	Function tracing enabled.
	TPM	TPM drivers are enabled.
	TS	Appropriate touchscreen support is enabled.
	UMS	USB Mass Storage support is enabled.
	USB	USB support is enabled.
	USBHID	USB Human Interface Device support is enabled.
	V4L	Video For Linux support is enabled.
	VGA	The VGA console has been enabled.
	VT	Virtual terminal support is enabled.
	WDT	Watchdog support is enabled.
	XT	IBM PC/XT MFM hard disk support is enabled.
	X86-32	X86-32, aka i386 architecture is enabled.
	X86-64	X86-64 architecture is enabled.
			More X86-64 boot options can be found in
			Documentation/x86/x86_64/boot-options.txt .
	X86	Either 32bit or 64bit x86 (same as X86-32+X86-64)
	XEN	Xen support is enabled

In addition, the following text indicates that the option:

	BUGS=	Relates to possible processor bugs on the said processor.
	KNL	Is a kernel start-up parameter.
	BOOT	Is a boot loader parameter.

Parameters denoted with BOOT are actually interpreted by the boot
loader, and have no meaning to the kernel directly.
Do not modify the syntax of boot loader parameters without extreme
need or coordination with <Documentation/x86/boot.txt>.

There are also arch-specific kernel-parameters not documented here.
See for example <Documentation/x86/x86_64/boot-options.txt>.

Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
a trailing = on the name of any parameter states that that parameter will
be entered as an environment variable, whereas its absence indicates that
it will appear as a kernel argument readable via /proc/cmdline by programs
running once the system is up.

The number of kernel parameters is not limited, but the length of the
complete command line (parameters including spaces etc.) is limited to
a fixed number of characters. This limit depends on the architecture
and is between 256 and 4096 characters. It is defined in the file
./include/asm/setup.h as COMMAND_LINE_SIZE.


	acpi=		[HW,ACPI,X86]
			Advanced Configuration and Power Interface
			Format: { force | off | ht | strict | noirq | rsdt }
			force -- enable ACPI if default was off
			off -- disable ACPI if default was on
			noirq -- do not use ACPI for IRQ routing
			ht -- run only enough ACPI to enable Hyper Threading
			strict -- Be less tolerant of platforms that are not
				strictly ACPI specification compliant.
			rsdt -- prefer RSDT over (default) XSDT

			See also Documentation/power/pm.txt, pci=noacpi

	acpi_rsdp=	[ACPI,EFI,KEXEC]
			Pass the RSDP address to the kernel, mostly used
			on machines running EFI runtime service to boot the
			second kernel for kdump.

	acpi_apic_instance=	[ACPI, IOAPIC]
			Format: <int>
			2: use 2nd APIC table, if available
			1,0: use 1st APIC table
			default: 0

	acpi_backlight=	[HW,ACPI]
			acpi_backlight=vendor
			acpi_backlight=video
			If set to vendor, prefer vendor specific driver
			(e.g. thinkpad_acpi, sony_acpi, etc.) instead
			of the ACPI video.ko driver.

	acpi.debug_layer=	[HW,ACPI,ACPI_DEBUG]
	acpi.debug_level=	[HW,ACPI,ACPI_DEBUG]
			Format: <int>
			CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
			debug output.  Bits in debug_layer correspond to a
			_COMPONENT in an ACPI source file, e.g.,
			    #define _COMPONENT ACPI_PCI_COMPONENT
			Bits in debug_level correspond to a level in
			ACPI_DEBUG_PRINT statements, e.g.,
			    ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
			The debug_level mask defaults to "info".  See
			Documentation/acpi/debug.txt for more information about
			debug layers and levels.

			Enable processor driver info messages:
			    acpi.debug_layer=0x20000000
			Enable PCI/PCI interrupt routing info messages:
			    acpi.debug_layer=0x400000
			Enable AML "Debug" output, i.e., stores to the Debug
			object while interpreting AML:
			    acpi.debug_layer=0xffffffff acpi.debug_level=0x2
			Enable all messages related to ACPI hardware:
			    acpi.debug_layer=0x2 acpi.debug_level=0xffffffff

			Some values produce so much output that the system is
			unusable.  The "log_buf_len" parameter may be useful
			if you need to capture more output.

	acpi_display_output=	[HW,ACPI]
			acpi_display_output=vendor
			acpi_display_output=video
			See above.

	acpi_irq_balance [HW,ACPI]
			ACPI will balance active IRQs
			default in APIC mode

	acpi_irq_nobalance [HW,ACPI]
			ACPI will not move active IRQs (default)
			default in PIC mode

	acpi_irq_isa=	[HW,ACPI] If irq_balance, mark listed IRQs used by ISA
			Format: <irq>,<irq>...

	acpi_irq_pci=	[HW,ACPI] If irq_balance, clear listed IRQs for
			use by PCI
			Format: <irq>,<irq>...

	acpi_no_auto_ssdt	[HW,ACPI] Disable automatic loading of SSDT

	acpi_os_name=	[HW,ACPI] Tell ACPI BIOS the name of the OS
			Format: To spoof as Windows 98: ="Microsoft Windows"

	acpi_osi=	[HW,ACPI] Modify list of supported OS interface strings
			acpi_osi="string1"	# add string1 -- only one string
			acpi_osi="!string2"	# remove built-in string2
			acpi_osi=		# disable all strings

	acpi_pm_good	[X86]
			Override the pmtimer bug detection: force the kernel
			to assume that this machine's pmtimer latches its value
			and always returns good values.

	acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
			Format: { level | edge | high | low }

	acpi_serialize	[HW,ACPI] force serialization of AML methods

	acpi_skip_timer_override [HW,ACPI]
			Recognize and ignore IRQ0/pin2 Interrupt Override.
			For broken nForce2 BIOS resulting in XT-PIC timer.

	acpi_sleep=	[HW,ACPI] Sleep options
			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
				  old_ordering, s4_nonvs }
			See Documentation/power/video.txt for information on
			s3_bios and s3_mode.
			s3_beep is for debugging; it makes the PC's speaker beep
			as soon as the kernel's real-mode entry point is called.
			s4_nohwsig prevents ACPI hardware signature from being
			used during resume from hibernation.
			old_ordering causes the ACPI 1.0 ordering of the _PTS
			control method, with respect to putting devices into
			low power states, to be enforced (the ACPI 2.0 ordering
			of _PTS is used by default).
			s4_nonvs prevents the kernel from saving/restoring the
			ACPI NVS memory during hibernation.

	acpi_use_timer_override [HW,ACPI]
			Use timer override. For some broken Nvidia NF5 boards
			that require a timer override, but don't have HPET

	acpi_enforce_resources=	[ACPI]
			{ strict | lax | no }
			Check for resource conflicts between native drivers
			and ACPI OperationRegions (SystemIO and SystemMemory
			only). IO ports and memory declared in ACPI might be
			used by the ACPI subsystem in arbitrary AML code and
			can interfere with legacy drivers.
			strict (default): access to resources claimed by ACPI
			is denied; legacy drivers trying to access reserved
			resources will fail to bind to device using them.
			lax: access to resources claimed by ACPI is allowed;
			legacy drivers trying to access reserved resources
			will bind successfully but a warning message is logged.
			no: ACPI OperationRegions are not marked as reserved,
			no further checks are performed.

	ad1848=		[HW,OSS]
			Format: <io>,<irq>,<dma>,<dma2>,<type>

	acpi_no_memhotplug [ACPI] Disable memory hotplug.  Useful for kdump
			   kernels.

	add_efi_memmap	[EFI; X86] Include EFI memory map in
			kernel's map of available physical RAM.

	advansys=	[HW,SCSI]
			See header of drivers/scsi/advansys.c.

	advwdt=		[HW,WDT] Advantech WDT
			Format: <iostart>,<iostop>

	aedsp16=	[HW,OSS] Audio Excel DSP 16
			Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
			See also header of sound/oss/aedsp16.c.

	agp=		[AGP]
			{ off | try_unsupported }
			off: disable AGP support
			try_unsupported: try to drive unsupported chipsets
				(may crash computer or cause data corruption)

	aha152x=	[HW,SCSI]
			See Documentation/scsi/aha152x.txt.

	aha1542=	[HW,SCSI]
			Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]

	aic7xxx=	[HW,SCSI]
			See Documentation/scsi/aic7xxx.txt.

	aic79xx=	[HW,SCSI]
			See Documentation/scsi/aic79xx.txt.

	align_va_addr=	[X86-64]
			Align virtual addresses by clearing slice [14:12] when
			allocating a VMA at process creation time. This option
			gives you up to 3% performance improvement on AMD F15h
			machines (where it is enabled by default) for a
			CPU-intensive style benchmark, and it can vary highly in
			a microbenchmark depending on workload and compiler.

			32: only for 32-bit processes
			64: only for 64-bit processes
			on: enable for both 32- and 64-bit processes
			off: disable for both 32- and 64-bit processes

	amd_iommu=	[HW,X86-84]
			Pass parameters to the AMD IOMMU driver in the system.
			Format: <a>,<b>,...
			Possible values are:
			on - enable AMD IOMMU (disabled by default)
			isolate - enable device isolation (each device, as far
			          as possible, will get its own protection
			          domain). This parameter also forces the
				  AMD IOMMU driver out of passthrough mode.
			share - put every device behind one IOMMU into the
				same protection domain. This parameter also
				forces the AMD IOMMU driver to not use
				passthrough mode.
			fullflush - enable flushing of IO/TLB entries when
				    they are unmapped. Otherwise they are
				    flushed before they will be reused, which
				    is a lot faster.

	amijoy.map=	[HW,JOY] Amiga joystick support
			Map of devices attached to JOY0DAT and JOY1DAT
			Format: <a>,<b>
			See also Documentation/kernel/input/joystick.txt

	analog.map=	[HW,JOY] Analog joystick and gamepad support
			Specifies type or capabilities of an analog joystick
			connected to one of 16 gameports
			Format: <type1>,<type2>,..<type16>

	apc=		[HW,SPARC]
			Power management functions (SPARCstation-4/5 + deriv.)
			Format: noidle
			Disable APC CPU standby support. SPARCstation-Fox does
			not play well with APC CPU idle - disable it if you have
			APC and your system crashes randomly.

	apic=		[APIC,X86-32] Advanced Programmable Interrupt Controller
			Change the output verbosity whilst booting
			Format: { quiet (default) | verbose | debug }
			Change the amount of debugging information output
			when initialising the APIC and IO-APIC components.

	apm=		[APM] Advanced Power Management
			See header of arch/x86/kernel/apm_32.c.

	arcrimi=	[HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
			Format: <io>,<irq>,<nodeID>

	ataflop=	[HW,M68k]

	atarimouse=	[HW,MOUSE] Atari Mouse

	atascsi=	[HW,SCSI] Atari SCSI

	atkbd.extra=	[HW] Enable extra LEDs and keys on IBM RapidAccess,
			EzKey and similar keyboards

	atkbd.reset=	[HW] Reset keyboard during initialization

	atkbd.set=	[HW] Select keyboard code set
			Format: <int> (2 = AT (default), 3 = PS/2)

	atkbd.scroll=	[HW] Enable scroll wheel on MS Office and similar
			keyboards

	atkbd.softraw=	[HW] Choose between synthetic and real raw mode
			Format: <bool> (0 = real, 1 = synthetic (default))

	atkbd.softrepeat= [HW]
			Use software keyboard repeat

	autotest	[IA64]

	baycom_epp=	[HW,AX25]
			Format: <io>,<mode>

	baycom_par=	[HW,AX25] BayCom Parallel Port AX.25 Modem
			Format: <io>,<mode>
			See header of drivers/net/hamradio/baycom_par.c.

	baycom_ser_fdx=	[HW,AX25]
			BayCom Serial Port AX.25 Modem (Full Duplex Mode)
			Format: <io>,<irq>,<mode>[,<baud>]
			See header of drivers/net/hamradio/baycom_ser_fdx.c.

	baycom_ser_hdx=	[HW,AX25]
			BayCom Serial Port AX.25 Modem (Half Duplex Mode)
			Format: <io>,<irq>,<mode>
			See header of drivers/net/hamradio/baycom_ser_hdx.c.

	boot_delay=	Milliseconds to delay each printk during boot.
			Values larger than 10 seconds (10000) are changed to
			no delay (0).
			Format: integer

	bootmem_debug	[KNL] Enable bootmem allocator debug messages.

	bttv.card=	[HW,V4L] bttv (bt848 + bt878 based grabber cards)
	bttv.radio=	Most important insmod options are available as
			kernel args too.
	bttv.pll=	See Documentation/video4linux/bttv/Insmod-options
	bttv.tuner=	and Documentation/video4linux/bttv/CARDLIST

	BusLogic=	[HW,SCSI]
			See drivers/scsi/BusLogic.c, comment before function
			BusLogic_ParseDriverOptions().

	c101=		[NET] Moxa C101 synchronous serial card

	cachesize=	[BUGS=X86-32] Override level 2 CPU cache size detection.
			Sometimes CPU hardware bugs make them report the cache
			size incorrectly. The kernel will attempt work arounds
			to fix known problems, but for some CPUs it is not
			possible to determine what the correct size should be.
			This option provides an override for these situations.

	capability.disable=
			[SECURITY] Disable capabilities.  This would normally
			be used only if an alternative security model is to be
			configured.  Potentially dangerous and should only be
			used if you are entirely sure of the consequences.

	ccw_timeout_log [S390]
			See Documentation/s390/CommonIO for details.

	cgroup_disable= [KNL] Disable a particular controller
			Format: {name of the controller(s) to disable}
				{Currently supported controllers - "memory"}

	checkreqprot	[SELINUX] Set initial checkreqprot flag value.
			Format: { "0" | "1" }
			See security/selinux/Kconfig help text.
			0 -- check protection applied by kernel (includes
				any implied execute protection).
			1 -- check protection requested by application.
			Default value is set via a kernel config option.
			Value can be changed at runtime via
				/selinux/checkreqprot.

	cio_ignore=	[S390]
			See Documentation/s390/CommonIO for details.

	clock=		[BUGS=X86-32, HW] gettimeofday clocksource override.
			[Deprecated]
			Forces specified clocksource (if available) to be used
			when calculating gettimeofday(). If specified
			clocksource is not available, it defaults to PIT.
			Format: { pit | tsc | cyclone | pmtmr }

	clocksource=	Override the default clocksource
			Format: <string>
			Override the default clocksource and use the clocksource
			with the name specified.
			Some clocksource names to choose from, depending on
			the platform:
			[all] jiffies (this is the base, fallback clocksource)
			[ACPI] acpi_pm
			[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
				pxa_timer,timer3,32k_counter,timer0_1
			[AVR32] avr32
			[X86-32] pit,hpet,tsc,vmi-timer;
				scx200_hrt on Geode; cyclone on IBM x440
			[MIPS] MIPS
			[PARISC] cr16
			[S390] tod
			[SH] SuperH
			[SPARC64] tick
			[X86-64] hpet,tsc

	clocksource_failover [GENERIC_TIME] Switch the clocksource if the
			     current clocksource is found to be unstable.

	clearcpuid=BITNUM [X86]
			Disable CPUID feature X for the kernel. See
			arch/x86/include/asm/cpufeature.h for the valid bit
			numbers. Note the Linux specific bits are not necessarily
			stable over kernel options, but the vendor specific
			ones should be.
			Also note that user programs calling CPUID directly
			or using the feature without checking anything
			will still see it. This just prevents it from
			being used by the kernel or shown in /proc/cpuinfo.
			Also note the kernel might malfunction if you disable
			some critical bits.

	cmo_free_hint=	[PPC] Format: { yes | no }
			Specify whether pages are marked as being inactive
			when they are freed.  This is used in CMO environments
			to determine OS memory pressure for page stealing by
			a hypervisor.
			Default: yes

	code_bytes	[X86] How many bytes of object code to print
			in an oops report.
			Range: 0 - 8192
			Default: 64

	com20020=	[HW,NET] ARCnet - COM20020 chipset
			Format:
			<io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]

	com90io=	[HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
			Format: <io>[,<irq>]

	com90xx=	[HW,NET]
			ARCnet - COM90xx chipset (memory-mapped buffers)
			Format: <io>[,<irq>[,<memstart>]]

	condev=		[HW,S390] console device
	conmode=

	console=	[KNL] Output console device and options.

		tty<n>	Use the virtual console device <n>.

		ttyS<n>[,options]
		ttyUSB0[,options]
			Use the specified serial port.  The options are of
			the form "bbbbpnf", where "bbbb" is the baud rate,
			"p" is parity ("n", "o", or "e"), "n" is number of
			bits, and "f" is flow control ("r" for RTS or
			omit it).  Default is "9600n8".

			See Documentation/serial-console.txt for more
			information.  See
			Documentation/networking/netconsole.txt for an
			alternative.

		uart[8250],io,<addr>[,options]
		uart[8250],mmio,<addr>[,options]
			Start an early, polled-mode console on the 8250/16550
			UART at the specified I/O port or MMIO address,
			switching to the matching ttyS device later.  The
			options are the same as for ttyS, above.

                If the device connected to the port is not a TTY but a braille
                device, prepend "brl," before the device type, for instance
			console=brl,ttyS0
		For now, only VisioBraille is supported.

	consoleblank=	[KNL] The console blank (screen saver) timeout in
			seconds. Defaults to 10*60 = 10mins. A value of 0
			disables the blank timer.

	coredump_filter=
			[KNL] Change the default value for
			/proc/<pid>/coredump_filter.
			See also Documentation/filesystems/proc.txt.

	cpcihp_generic=	[HW,PCI] Generic port I/O CompactPCI driver
			Format:
			<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]

	crashkernel=nn[KMG]@ss[KMG]
			[KNL] Reserve a chunk of physical memory to
			hold a kernel to switch to with kexec on panic.

	crashkernel=range1:size1[,range2:size2,...][@offset]
			[KNL] Same as above, but depends on the memory
			in the running system. The syntax of range is
			start-[end] where start and end are both
			a memory unit (amount[KMG]). See also
			Documentation/kdump/kdump.txt for a example.

	cs89x0_dma=	[HW,NET]
			Format: <dma>

	cs89x0_media=	[HW,NET]
			Format: { rj45 | aui | bnc }

	dasd=		[HW,NET]
			See header of drivers/s390/block/dasd_devmap.c.

	db9.dev[2|3]=	[HW,JOY] Multisystem joystick support via parallel port
			(one device per port)
			Format: <port#>,<type>
			See also Documentation/input/joystick-parport.txt

	ddebug_query=   [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
			time. See Documentation/dynamic-debug-howto.txt for
			details.  Deprecated, see dyndbg.

	debug		[KNL] Enable kernel debugging (events log level).

	debug_locks_verbose=
			[KNL] verbose self-tests
			Format=<0|1>
			Print debugging info while doing the locking API
			self-tests.
			We default to 0 (no extra messages), setting it to
			1 will print _a lot_ more information - normally
			only useful to kernel developers.

	debug_objects	[KNL] Enable object debugging

	no_debug_objects
			[KNL] Disable object debugging

	debugpat	[X86] Enable PAT debugging

	decnet.addr=	[HW,NET]
			Format: <area>[,<node>]
			See also Documentation/networking/decnet.txt.

	default_hugepagesz=
			[same as hugepagesz=] The size of the default
			HugeTLB page size. This is the size represented by
			the legacy /proc/ hugepages APIs, used for SHM, and
			default size when mounting hugetlbfs filesystems.
			Defaults to the default architecture's huge page size
			if not specified.

	dhash_entries=	[KNL]
			Set number of hash buckets for dentry cache.

	digi=		[HW,SERIAL]
			IO parameters + enable/disable command.

	digiepca=	[HW,SERIAL]
			See drivers/char/README.epca and
			Documentation/serial/digiepca.txt.

	disable_cpu_apicid= [X86,APIC,SMP]
			Format: <int>
			The number of initial APIC ID for the
			corresponding CPU to be disabled at boot,
			mostly used for the kdump 2nd kernel to
			disable BSP to wake up multiple CPUs without
			causing system reset or hang due to sending
			INIT from AP to BSP.

	disable_ddw     [PPC]
			Disable Dynamic DMA Window support. Use this if
			to workaround buggy firmware.

	disable_mtrr_cleanup [X86]
			The kernel tries to adjust MTRR layout from continuous
			to discrete, to make X server driver able to add WB
			entry later. This parameter disables that.

	disable_mtrr_trim [X86, Intel and AMD only]
			By default the kernel will trim any uncacheable
			memory out of your available memory pool based on
			MTRR settings.  This parameter disables that behavior,
			possibly causing your machine to run very slowly.

	disable_timer_pin_1 [X86]
			Disable PIN 1 of APIC timer
			Can be useful to work around chipset bugs.

	dmasound=	[HW,OSS] Sound subsystem buffers

	dma_debug=off	If the kernel is compiled with DMA_API_DEBUG support,
			this option disables the debugging code at boot.

	dma_debug_entries=<number>
			This option allows to tune the number of preallocated
			entries for DMA-API debugging code. One entry is
			required per DMA-API allocation. Use this if the
			DMA-API debugging code disables itself because the
			architectural default is too low.

	dma_debug_driver=<driver_name>
			With this option the DMA-API debugging driver
			filter feature can be enabled at boot time. Just
			pass the driver to filter for as the parameter.
			The filter can be disabled or changed to another
			driver later using sysfs.

	dscc4.setup=	[NET]

	dtc3181e=	[HW,SCSI]

	dyndbg[="val"]		[KNL,DYNAMIC_DEBUG]
	module.dyndbg[="val"]
			Enable debug messages at boot time.  See
			Documentation/dynamic-debug-howto.txt for details.

	earlycon=	[KNL] Output early console device and options.
		uart[8250],io,<addr>[,options]
		uart[8250],mmio,<addr>[,options]
			Start an early, polled-mode console on the 8250/16550
			UART at the specified I/O port or MMIO address.
			The options are the same as for ttyS, above.

	earlyprintk=	[X86,SH,BLACKFIN]
			earlyprintk=vga
			earlyprintk=efi
			earlyprintk=serial[,ttySn[,baudrate]]
			earlyprintk=ttySn[,baudrate]
			earlyprintk=dbgp[debugController#]

			Append ",keep" to not disable it when the real console
			takes over.

			Only one of vga, efi, serial or usb debug port can
			be used at a time.

			Currently only ttyS0 and ttyS1 are supported.

			Interaction with the standard serial driver is not
			very good.

			The VGA and EFI output is eventually overwritten by
			the real console.

	eata=		[HW,SCSI]

	edac_report=	[HW,EDAC] Control how to report EDAC event
			Format: {"on" | "off" | "force"}
			on: enable EDAC to report H/W event. May be overridden
			by other higher priority error reporting module.
			off: disable H/W event reporting through EDAC.
			force: enforce the use of EDAC to report H/W event.
			default: on.

	edd=		[EDD]
			Format: {"off" | "on" | "skip[mbr]"}

	efi_smbios_addr= [X86,EFI]
			Parameter used to specify location of SMBIOS for
			EFI systems.  Used by kexec-tools for kdump.

	eisa_irq_edge=	[PARISC,HW]
			See header of drivers/parisc/eisa.c.

	elanfreq=	[X86-32]
			See comment before function elanfreq_setup() in
			arch/x86/kernel/cpu/cpufreq/elanfreq.c.

	elevator=	[IOSCHED]
			Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
			See Documentation/block/as-iosched.txt and
			Documentation/block/deadline-iosched.txt for details.

	elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
			Specifies physical address of start of kernel core
			image elf header and optionally the size. Generally
			kexec loader will pass this option to capture kernel.
			See Documentation/kdump/kdump.txt for details.

	enable_mtrr_cleanup [X86]
			The kernel tries to adjust MTRR layout from continuous
			to discrete, to make X server driver able to add WB
			entry later. This parameter enables that.

	enable_timer_pin_1 [X86]
			Enable PIN 1 of APIC timer
			Can be useful to work around chipset bugs
			(in particular on some ATI chipsets).
			The kernel tries to set a reasonable default.

	enforcing	[SELINUX] Set initial enforcing status.
			Format: {"0" | "1"}
			See security/selinux/Kconfig help text.
			0 -- permissive (log only, no denials).
			1 -- enforcing (deny and log).
			Default value is 0.
			Value can be changed at runtime via /selinux/enforce.

	erst_disable	[ACPI]
			Disable Error Record Serialization Table (ERST)
			support.

	ether=		[HW,NET] Ethernet cards parameters
			This option is obsoleted by the "netdev=" option, which
			has equivalent usage. See its documentation for details.

	eurwdt=		[HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
			Format: <io>[,<irq>]

	failslab=
	fail_page_alloc=
	fail_make_request=[KNL]
			General fault injection mechanism.
			Format: <interval>,<probability>,<space>,<times>
			See also /Documentation/fault-injection/.

	fd_mcs=		[HW,SCSI]
			See header of drivers/scsi/fd_mcs.c.

	fdomain=	[HW,SCSI]
			See header of drivers/scsi/fdomain.c.

	floppy=		[HW]
			See Documentation/blockdev/floppy.txt.

	force_hrtimer_reprogram= [KNL] Force the reprogramming of expired
			timers in hrtimer_reprogram().

	force_pal_cache_flush
			[IA-64] Avoid check_sal_cache_flush which may hang on
			buggy SAL_CACHE_FLUSH implementations. Using this
			parameter will force ia64_sal_cache_flush to call
			ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.

	ftrace=[tracer]
			[FTRACE] will set and start the specified tracer
			as early as possible in order to facilitate early
			boot debugging.

	ftrace_dump_on_oops
			[FTRACE] will dump the trace buffers on oops.

	ftrace_filter=[function-list]
			[FTRACE] Limit the functions traced by the function
			tracer at boot up. function-list is a comma separated
			list of functions. This list can be changed at run
			time by the set_ftrace_filter file in the debugfs
			tracing directory. 

	ftrace_notrace=[function-list]
			[FTRACE] Do not trace the functions specified in
			function-list. This list can be changed at run time
			by the set_ftrace_notrace file in the debugfs
			tracing directory.

	gamecon.map[2|3]=
			[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
			support via parallel port (up to 5 devices per port)
			Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
			See also Documentation/input/joystick-parport.txt

	gamma=		[HW,DRM]

	gart_fix_e820=  [X86_64] disable the fix e820 for K8 GART
			Format: off | on
			default: on

	gcov_persist=	[GCOV] When non-zero (default), profiling data for
			kernel modules is saved and remains accessible via
			debugfs, even when the module is unloaded/reloaded.
			When zero, profiling data is discarded and associated
			debugfs files are removed at module unload time.

	gdth=		[HW,SCSI]
			See header of drivers/scsi/gdth.c.

	gpt		[EFI] Forces disk with valid GPT signature but
			invalid Protective MBR to be treated as GPT.

	gvp11=		[HW,SCSI]

	hardlockup_all_cpu_backtrace=
			[KNL] Should the hard-lockup detector generate
			backtraces on all cpus.
			Format: <integer>

	hashdist=	[KNL,NUMA] Large hashes allocated during boot
			are distributed across NUMA nodes.  Defaults on
			for 64bit NUMA, off otherwise.
			Format: 0 | 1 (for off | on)

	hcl=		[IA-64] SGI's Hardware Graph compatibility layer

	hd=		[EIDE] (E)IDE hard drive subsystem geometry
			Format: <cyl>,<head>,<sect>

	hest_disable	[ACPI]
			Disable Hardware Error Source Table (HEST) support;
			corresponding firmware-first mode error processing
			logic will be disabled.

	highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact
			size of <nn>. This works even on boxes that have no
			highmem otherwise. This also works to reduce highmem
			size on bigger boxes.

	highres=	[KNL] Enable/disable high resolution timer mode.
			Valid parameters: "on", "off"
			Default: "on"

	hisax=		[HW,ISDN]
			See Documentation/isdn/README.HiSax.

	hlt		[BUGS=ARM,SH]

	hpet=		[X86-32,HPET] option to control HPET usage
			Format: { enable (default) | disable | force |
				verbose }
			disable: disable HPET and use PIT instead
			force: allow force enabled of undocumented chips (ICH4,
				VIA, nVidia)
			verbose: show contents of HPET registers during setup

	hpet_mmap	[HW, X86_64] Enable userspace mapping of HPET
			registers for faster HPET access by userspace
			processes.

	hugepages=	[HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
	hugepagesz=	[HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
			On x86-64 and powerpc, this option can be specified
			multiple times interleaved with hugepages= to reserve
			huge pages of different sizes. Valid pages sizes on
			x86-64 are 2M (when the CPU supports "pse") and 1G
			(when the CPU supports the "pdpe1gb" cpuinfo flag)
			Note that 1GB pages can only be allocated at boot time
			using hugepages= and not freed afterwards.

	hvc_iucv=	[S390] Number of z/VM IUCV hypervisor console (HVC)
			       terminal devices. Valid values: 0..8
	hvc_iucv_allow=	[S390] Comma-separated list of z/VM user IDs.
			       If specified, z/VM IUCV HVC accepts connections
			       from listed z/VM user IDs only.

	i2c_bus=	[HW] Override the default board specific I2C bus speed
			     or register an additional I2C bus that is not
			     registered from board initialization code.
			     Format:
			     <bus_id>,<clkrate>

	i8042.debug	[HW] Toggle i8042 debug mode
	i8042.direct	[HW] Put keyboard port into non-translated mode
	i8042.dumbkbd	[HW] Pretend that controller can only read data from
			     keyboard and cannot control its state
			     (Don't attempt to blink the leds)
	i8042.noaux	[HW] Don't check for auxiliary (== mouse) port
	i8042.nokbd	[HW] Don't check/create keyboard port
	i8042.noloop	[HW] Disable the AUX Loopback command while probing
			     for the AUX port
	i8042.nomux	[HW] Don't check presence of an active multiplexing
			     controller
	i8042.nopnp	[HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
			     controllers
	i8042.panicblink=
			[HW] Frequency with which keyboard LEDs should blink
			     when kernel panics (default is 0.5 sec)
	i8042.reset	[HW] Reset the controller during init and cleanup
	i8042.unlock	[HW] Unlock (ignore) the keylock

	i810=		[HW,DRM]

	i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
			indicates that the driver is running on unsupported
			hardware.
	i8k.force	[HW] Activate i8k driver even if SMM BIOS signature
			does not match list of supported models.
	i8k.power_status
			[HW] Report power status in /proc/i8k
			(disabled by default)
	i8k.restricted	[HW] Allow controlling fans only if SYS_ADMIN
			capability is set.

	ibmmcascsi=	[HW,MCA,SCSI] IBM MicroChannel SCSI adapter
			See Documentation/mca.txt.

	icn=		[HW,ISDN]
			Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]

	ide-core.nodma=	[HW] (E)IDE subsystem
			Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
			.vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
			.cdrom .chs .ignore_cable are additional options
			See Documentation/ide/ide.txt.

	ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
			Claim all unknown PCI IDE storage controllers.

	idle=		[X86]
			Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
			Poll forces a polling idle loop that can slightly
			improve the performance of waking up a idle CPU, but
			will use a lot of power and make the system run hot.
			Not recommended.
			idle=mwait: On systems which support MONITOR/MWAIT but
			the kernel chose to not use it because it doesn't save
			as much power as a normal idle loop, use the
			MONITOR/MWAIT idle loop anyways. Performance should be
			the same as idle=poll.
			idle=halt: Halt is forced to be used for CPU idle.
			In such case C2/C3 won't be used again.
			idle=nomwait: Disable mwait for CPU C-states

	ignore_loglevel	[KNL]
			Ignore loglevel setting - this will print /all/
			kernel messages to the console. Useful for debugging.

	ihash_entries=	[KNL]
			Set number of hash buckets for inode cache.

	ima_audit=	[IMA]
			Format: { "0" | "1" }
			0 -- integrity auditing messages. (Default)
			1 -- enable informational integrity auditing messages.

	ima_hash=	[IMA]
			Format: { "sha1" | "md5" }
			default: "sha1"

	ima_tcb		[IMA]
			Load a policy which meets the needs of the Trusted
			Computing Base.  This means IMA will measure all
			programs exec'd, files mmap'd for exec, and all files
			opened for read by uid=0.

	in2000=		[HW,SCSI]
			See header of drivers/scsi/in2000.c.

	init=		[KNL]
			Format: <full_path>
			Run specified binary instead of /sbin/init as init
			process.

	initcall_debug	[KNL] Trace initcalls as they are executed.  Useful
			for working out where the kernel is dying during
			startup.

	initcall_blacklist=  [KNL] Do not execute a comma-separated list of
			initcall functions.  Useful for debugging built-in
			modules and initcalls.

	initrd=		[BOOT] Specify the location of the initial ramdisk

	inport.irq=	[HW] Inport (ATI XL and Microsoft) busmouse driver
			Format: <irq>

	int_pln_enable  [x86] Enable power limit notification interrupt

	intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
		on
			Enable intel iommu driver.
		off
			Disable intel iommu driver.
		igfx_off [Default Off]
			By default, gfx is mapped as normal device. If a gfx
			device has a dedicated DMAR unit, the DMAR unit is
			bypassed by not enabling DMAR with this option. In
			this case, gfx device will use physical address for
			DMA.
		pt64 [Default Off]
			Enable 64 bit pass through mode if the kernel has the
			capability.  Also disables forcedac, unless that option
			follows this option.
		forcedac [x86_64]
			With this option iommu will not optimize to look
			for io virtual address below 32 bit forcing dual
			address cycle on pci bus for cards supporting greater
			than 32 bit addressing. The default is to look
			for translation below 32 bit and if not available
			then look in the higher range.  Note that pt64 disables
			this option, so this must follow that option to be
			effective.
		strict [Default Off]
			With this option on every unmap_single operation will
			result in a hardware IOTLB flush operation as opposed
			to batching them for performance.
		sp_off [Default Off]
			By default, super page will be supported if Intel IOMMU
			has the capability. With this option, super page will
			not be supported.

	intel_idle.max_cstate=	[KNL,HW,ACPI,X86]
			0	disables intel_idle and fall back on acpi_idle.
			1 to 6	specify maximum depth of C-state.

	intremap=	[X86-64, Intel-IOMMU]
			on	enable Interrupt Remapping (default)
			off	disable Interrupt Remapping
			nosid	disable Source ID checking
			no_x2apic_optout
				BIOS x2APIC opt-out request will be ignored

	inttest=	[IA64]

	iomem=		Disable strict checking of access to MMIO memory
		strict	regions from userspace.
		relaxed

	iommu=		[x86]
		off
		force
		noforce
		biomerge
		panic
		nopanic
		merge
		nomerge
		forcesac
		soft
		pt	[x86, IA64]

	io7=		[HW] IO7 for Marvel based alpha systems
			See comment before marvel_specify_io7 in
			arch/alpha/kernel/core_marvel.c.

	io_delay=	[X86] I/O delay method
		0x80
			Standard port 0x80 based delay
		0xed
			Alternate port 0xed based delay (needed on some systems)
		udelay
			Simple two microseconds delay
		none
			No delay

	ip=		[IP_PNP]
			See Documentation/filesystems/nfs/nfsroot.txt.

	ip2=		[HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
			See comment before ip2_setup() in
			drivers/char/ip2/ip2base.c.

	ips=		[HW,SCSI] Adaptec / IBM ServeRAID controller
			See header of drivers/scsi/ips.c.

	irqfixup	[HW]
			When an interrupt is not handled search all handlers
			for it. Intended to get systems with badly broken
			firmware running.

	irqpoll		[HW]
			When an interrupt is not handled search all handlers
			for it. Also check all handlers each timer
			interrupt. Intended to get systems with badly broken
			firmware running.

	isapnp=		[ISAPNP]
			Format: <RDP>,<reset>,<pci_scan>,<verbosity>

	isolcpus=	[KNL,SMP] Isolate CPUs from the general scheduler.
			Format:
			<cpu number>,...,<cpu number>
			or
			<cpu number>-<cpu number>
			(must be a positive range in ascending order)
			or a mixture
			<cpu number>,...,<cpu number>-<cpu number>

			This option can be used to specify one or more CPUs
			to isolate from the general SMP balancing and scheduling
			algorithms. You can move a process onto or off an
			"isolated" CPU via the CPU affinity syscalls or cpuset.
			<cpu number> begins at 0 and the maximum value is
			"number of CPUs in system - 1".

			This option is the preferred way to isolate CPUs. The
			alternative -- manually setting the CPU mask of all
			tasks in the system -- can cause problems and
			suboptimal load balancer performance.

	iucv=		[HW,NET]

	js=		[HW,JOY] Analog joystick
			See Documentation/input/joystick.txt.

	keepinitrd	[HW,ARM]

	kernelcore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
			specifies the amount of memory usable by the kernel
			for non-movable allocations.  The requested amount is
			spread evenly throughout all nodes in the system. The
			remaining memory in each node is used for Movable
			pages. In the event, a node is too small to have both
			kernelcore and Movable pages, kernelcore pages will
			take priority and other nodes will have a larger number
			of Movable pages.  The Movable zone is used for the
			allocation of pages that may be reclaimed or moved
			by the page migration subsystem.  This means that
			HugeTLB pages may not be allocated from this zone.
			Note that allocations like PTEs-from-HighMem still
			use the HighMem zone if it exists, and the Normal
			zone if it does not.

	kgdboc=		[HW] kgdb over consoles.
			Requires a tty driver that supports console polling.
			(only serial supported for now)
			Format: <serial_device>[,baud]

	kmac=		[MIPS] korina ethernet MAC address.
			Configure the RouterBoard 532 series on-chip
			Ethernet adapter MAC address.

	kmemleak=	[KNL] Boot-time kmemleak enable/disable
			Valid arguments: on, off
			Default: on

	kstack=N	[X86] Print N words from the kernel stack
			in oops dumps.

	kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
			Default is 0 (don't ignore, but inject #GP)

	kvm.oos_shadow=	[KVM] Disable out-of-sync shadow paging.
			Default is 1 (enabled)

	kvm-amd.nested=	[KVM,AMD] Allow nested virtualization in KVM/SVM.
			Default is 0 (off)

	kvm-amd.npt=	[KVM,AMD] Disable nested paging (virtualized MMU)
			for all guests.
			Default is 1 (enabled) if in 64bit or 32bit-PAE mode

	kvm-intel.bypass_guest_pf=
			[KVM,Intel] Disables bypassing of guest page faults
			on Intel chips. Default is 1 (enabled)

	kvm-intel.ept=	[KVM,Intel] Disable extended page tables
			(virtualized MMU) support on capable Intel chips.
			Default is 1 (enabled)

	kvm-intel.emulate_invalid_guest_state=
			[KVM,Intel] Enable emulation of invalid guest states
			Default is 0 (disabled)

	kvm-intel.flexpriority=
			[KVM,Intel] Disable FlexPriority feature (TPR shadow).
			Default is 1 (enabled)

	kvm-intel.unrestricted_guest=
			[KVM,Intel] Disable unrestricted guest feature
			(virtualized real and unpaged mode) on capable
			Intel chips. Default is 1 (enabled)

	kvm-intel.vpid=	[KVM,Intel] Disable Virtual Processor Identification
			feature (tagged TLBs) on capable Intel chips.
			Default is 1 (enabled)

	l2cr=		[PPC]

	l3cr=		[PPC]

	lapic		[X86-32,APIC] Enable the local APIC even if BIOS
			disabled it.

	lapic_timer_c2_ok	[X86,APIC] trust the local apic timer
			in C2 power state.

	libata.dma=	[LIBATA] DMA control
			libata.dma=0	  Disable all PATA and SATA DMA
			libata.dma=1	  PATA and SATA Disk DMA only
			libata.dma=2	  ATAPI (CDROM) DMA only
			libata.dma=4	  Compact Flash DMA only 
			Combinations also work, so libata.dma=3 enables DMA
			for disks and CDROMs, but not CFs.
	
	libata.ignore_hpa=	[LIBATA] Ignore HPA limit
			libata.ignore_hpa=0	  keep BIOS limits (default)
			libata.ignore_hpa=1	  ignore limits, using full disk

	libata.noacpi	[LIBATA] Disables use of ACPI in libata suspend/resume
			when set.
			Format: <int>

	libata.force=	[LIBATA] Force configurations.  The format is comma
			separated list of "[ID:]VAL" where ID is
			PORT[:DEVICE].  PORT and DEVICE are decimal numbers
			matching port, link or device.  Basically, it matches
			the ATA ID string printed on console by libata.  If
			the whole ID part is omitted, the last PORT and DEVICE
			values are used.  If ID hasn't been specified yet, the
			configuration applies to all ports, links and devices.

			If only DEVICE is omitted, the parameter applies to
			the port and all links and devices behind it.  DEVICE
			number of 0 either selects the first device or the
			first fan-out link behind PMP device.  It does not
			select the host link.  DEVICE number of 15 selects the
			host link and device attached to it.

			The VAL specifies the configuration to force.  As long
			as there's no ambiguity shortcut notation is allowed.
			For example, both 1.5 and 1.5G would work for 1.5Gbps.
			The following configurations can be forced.

			* Cable type: 40c, 80c, short40c, unk, ign or sata.
			  Any ID with matching PORT is used.

			* SATA link speed limit: 1.5Gbps or 3.0Gbps.

			* Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
			  udma[/][16,25,33,44,66,100,133] notation is also
			  allowed.

			* [no]ncq: Turn on or off NCQ.

			* nohrst, nosrst, norst: suppress hard, soft
                          and both resets.

			* rstonce: only attempt one reset during
			  hot-unplug link recovery

			If there are multiple matching configurations changing
			the same attribute, the last one is used.

	lmb=debug	[KNL] Enable lmb debug messages.

	load_ramdisk=	[RAM] List of ramdisks to load from floppy
			See Documentation/blockdev/ramdisk.txt.

	lockd.nlm_grace_period=P  [NFS] Assign grace period.
			Format: <integer>

	lockd.nlm_tcpport=N	[NFS] Assign TCP port.
			Format: <integer>

	lockd.nlm_timeout=T	[NFS] Assign timeout value.
			Format: <integer>

	lockd.nlm_udpport=M	[NFS] Assign UDP port.
			Format: <integer>

	logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
			Format: <irq>

	loglevel=	All Kernel Messages with a loglevel smaller than the
			console loglevel will be printed to the console. It can
			also be changed with klogd or other programs. The
			loglevels are defined as follows:

			0 (KERN_EMERG)		system is unusable
			1 (KERN_ALERT)		action must be taken immediately
			2 (KERN_CRIT)		critical conditions
			3 (KERN_ERR)		error conditions
			4 (KERN_WARNING)	warning conditions
			5 (KERN_NOTICE)		normal but significant condition
			6 (KERN_INFO)		informational
			7 (KERN_DEBUG)		debug-level messages

	log_buf_len=n	Sets the size of the printk ring buffer, in bytes.
			Format: { n | nk | nM }
			n must be a power of two.  The default size
			is set in the kernel config file.

	logo.nologo	[FB] Disables display of the built-in Linux logo.
			This may be used to provide more screen space for
			kernel log messages and is useful when debugging
			kernel boot problems.

	lp=0		[LP]	Specify parallel ports to use, e.g,
	lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses
	lp=reset		first parallel port). 'lp=0' disables the
	lp=auto			printer driver. 'lp=reset' (which can be
				specified in addition to the ports) causes
				attached printers to be reset. Using
				lp=port1,port2,... specifies the parallel ports
				to associate lp devices with, starting with
				lp0. A port specification may be 'none' to skip
				that lp device, or a parport name such as
				'parport0'. Specifying 'lp=auto' instead of a
				port specification list means that device IDs
				from each port should be examined, to see if
				an IEEE 1284-compliant printer is attached; if
				so, the driver will manage that printer.
				See also header of drivers/char/lp.c.

	lpj=n		[KNL]
			Sets loops_per_jiffy to given constant, thus avoiding
			time-consuming boot-time autodetection (up to 250 ms per
			CPU). 0 enables autodetection (default). To determine
			the correct value for your kernel, boot with normal
			autodetection and see what value is printed. Note that
			on SMP systems the preset will be applied to all CPUs,
			which is likely to cause problems if your CPUs need
			significantly divergent settings. An incorrect value
			will cause delays in the kernel to be wrong, leading to
			unpredictable I/O errors and other breakage. Although
			unlikely, in the extreme case this might damage your
			hardware.

	ltpc=		[NET]
			Format: <io>,<irq>,<dma>

	mac5380=	[HW,SCSI] Format:
			<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>

	machvec=	[IA64] Force the use of a particular machine-vector
			(machvec) in a generic kernel.
			Example: machvec=hpzx1_swiotlb

	machtype=	[Loongson] Share the same kernel image file between different
			 yeeloong laptop.
			Example: machtype=lemote-yeeloong-2f-7inch

	max_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory greater
			than or equal to this physical address is ignored.

	maxcpus=	[SMP] Maximum number of processors that	an SMP kernel
			should make use of.  maxcpus=n : n >= 0 limits the
			kernel to using 'n' processors.  n=0 is a special case,
			it is equivalent to "nosmp", which also disables
			the IO APIC.

	max_loop=	[LOOP] Maximum number of loopback devices that can
			be mounted
			Format: <1-256>

	max_luns=	[SCSI] Maximum number of LUNs to probe.
			Should be between 1 and 2^32-1.

	max_report_luns=
			[SCSI] Maximum number of LUNs received.
			Should be between 1 and 16384.

	mcatest=	[IA-64]

	mce		[X86-32] Machine Check Exception

	mce=option	[X86-64] See Documentation/x86/x86_64/boot-options.txt

	md=		[HW] RAID subsystems devices and level
			See Documentation/md.txt.

	mdacon=		[MDA]
			Format: <first>,<last>
			Specifies range of consoles to be captured by the MDA.

	mem=nn[KMG]	[KNL,BOOT] Force usage of a specific amount of memory
			Amount of memory to be used when the kernel is not able
			to see the whole system memory or for test.
			[X86-32] Use together with memmap= to avoid physical
			address space collisions. Without memmap= PCI devices
			could be placed at addresses belonging to unused RAM.

	mem=nopentium	[BUGS=X86-32] Disable usage of 4MB pages for kernel
			memory.

	memchunk=nn[KMG]
			[KNL,SH] Allow user to override the default size for
			per-device physically contiguous DMA buffers.

	memmap=exactmap	[KNL,X86] Enable setting of an exact
			E820 memory map, as specified by the user.
			Such memmap=exactmap lines can be constructed based on
			BIOS output or other requirements. See the memmap=nn@ss
			option description.

	memmap=nn[KMG]@ss[KMG]
			[KNL] Force usage of a specific region of memory
			Region of memory to be used, from ss to ss+nn.

	memmap=nn[KMG]#ss[KMG]
			[KNL,ACPI] Mark specific memory as ACPI data.
			Region of memory to be used, from ss to ss+nn.

	memmap=nn[KMG]$ss[KMG]
			[KNL,ACPI] Mark specific memory as reserved.
			Region of memory to be used, from ss to ss+nn.
			Example: Exclude memory from 0x18690000-0x1869ffff
			         memmap=64K$0x18690000
			         or
			         memmap=0x10000$0x18690000

	memory_corruption_check=0/1 [X86]
			Some BIOSes seem to corrupt the first 64k of
			memory when doing things like suspend/resume.
			Setting this option will scan the memory
			looking for corruption.  Enabling this will
			both detect corruption and prevent the kernel
			from using the memory being corrupted.
			However, its intended as a diagnostic tool; if
			repeatable BIOS-originated corruption always
			affects the same memory, you can use memmap=
			to prevent the kernel from using that memory.

	memory_corruption_check_size=size [X86]
			By default it checks for corruption in the low
			64k, making this memory unavailable for normal
			use.  Use this parameter to scan for
			corruption in more or less memory.

	memory_corruption_check_period=seconds [X86]
			By default it checks for corruption every 60
			seconds.  Use this parameter to check at some
			other rate.  0 disables periodic checking.

	memtest=	[KNL,X86] Enable memtest
			Format: <integer>
			default : 0 <disable>
			Specifies the number of memtest passes to be
			performed. Each pass selects another test
			pattern from a given set of patterns. Memtest
			fills the memory with this pattern, validates
			memory contents and reserves bad memory
			regions that are detected.

	meye.*=		[HW] Set MotionEye Camera parameters
			See Documentation/video4linux/meye.txt.

	mfgpt_irq=	[IA-32] Specify the IRQ to use for the
			Multi-Function General Purpose Timers on AMD Geode
			platforms.

	mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when
			the BIOS has incorrectly applied a workaround. TinyBIOS
			version 0.98 is known to be affected, 0.99 fixes the
			problem by letting the user disable the workaround.

	mga=		[HW,DRM]

	min_addr=nn[KMG]	[KNL,BOOT,ia64] All physical memory below this
			physical address is ignored.

	mini2440=	[ARM,HW,KNL]
			Format:[0..2][b][c][t]
			Default: "0tb"
			MINI2440 configuration specification:
			0 - The attached screen is the 3.5" TFT
			1 - The attached screen is the 7" TFT
			2 - The VGA Shield is attached (1024x768)
			Leaving out the screen size parameter will not load
			the TFT driver, and the framebuffer will be left
			unconfigured.
			b - Enable backlight. The TFT backlight pin will be
			linked to the kernel VESA blanking code and a GPIO
			LED. This parameter is not necessary when using the
			VGA shield.
			c - Enable the s3c camera interface.
			t - Reserved for enabling touchscreen support. The
			touchscreen support is not enabled in the mainstream
			kernel as of 2.6.30, a preliminary port can be found
			in the "bleeding edge" mini2440 support kernel at
			http://repo.or.cz/w/linux-2.6/mini2440.git

	mminit_loglevel=
			[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
			parameter allows control of the logging verbosity for
			the additional memory initialisation checks. A value
			of 0 disables mminit logging and a level of 4 will
			log everything. Information is printed at KERN_DEBUG
			so loglevel=8 may also need to be specified.

	mousedev.tap_time=
			[MOUSE] Maximum time between finger touching and
			leaving touchpad surface for touch to be considered
			a tap and be reported as a left button click (for
			touchpads working in absolute mode only).
			Format: <msecs>
	mousedev.xres=	[MOUSE] Horizontal screen resolution, used for devices
			reporting absolute coordinates, such as tablets
	mousedev.yres=	[MOUSE] Vertical screen resolution, used for devices
			reporting absolute coordinates, such as tablets

	movablecore=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
			is similar to kernelcore except it specifies the
			amount of memory used for migratable allocations.
			If both kernelcore and movablecore is specified,
			then kernelcore will be at *least* the specified
			value but may be more. If movablecore on its own
			is specified, the administrator must be careful
			that the amount of memory usable for all allocations
			is not too small.

	mpu401=		[HW,OSS]
			Format: <io>,<irq>

	MTD_Partition=	[MTD]
			Format: <name>,<region-number>,<size>,<offset>

	MTD_Region=	[MTD] Format:
			<name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]

	mtdparts=	[MTD]
			See drivers/mtd/cmdlinepart.c.

	onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration

			Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]

			boundary - index of last SLC block on Flex-OneNAND.
				   The remaining blocks are configured as MLC blocks.
			lock	 - Configure if Flex-OneNAND boundary should be locked.
				   Once locked, the boundary cannot be changed.
				   1 indicates lock status, 0 indicates unlock status.

	mtdset=		[ARM]
			ARM/S3C2412 JIVE boot control

			See arch/arm/mach-s3c2412/mach-jive.c

	mtouchusb.raw_coordinates=
			[HW] Make the MicroTouch USB driver use raw coordinates
			('y', default) or cooked coordinates ('n')

	mtrr_chunk_size=nn[KMG] [X86]
			used for mtrr cleanup. It is largest continuous chunk
			that could hold holes aka. UC entries.

	mtrr_gran_size=nn[KMG] [X86]
			Used for mtrr cleanup. It is granularity of mtrr block.
			Default is 1.
			Large value could prevent small alignment from
			using up MTRRs.

	mtrr_spare_reg_nr=n [X86]
			Format: <integer>
			Range: 0,7 : spare reg number
			Default : 1
			Used for mtrr cleanup. It is spare mtrr entries number.
			Set to 2 or more if your graphical card needs more.

	n2=		[NET] SDL Inc. RISCom/N2 synchronous serial card

	NCR_D700=	[HW,SCSI]
			See header of drivers/scsi/NCR_D700.c.

	ncr5380=	[HW,SCSI]

	ncr53c400=	[HW,SCSI]

	ncr53c400a=	[HW,SCSI]

	ncr53c406a=	[HW,SCSI]

	ncr53c8xx=	[HW,SCSI]

	netdev=		[NET] Network devices parameters
			Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
			Note that mem_start is often overloaded to mean
			something different and driver-specific.
			This usage is only documented in each driver source
			file if at all.

	nf_conntrack.acct=
			[NETFILTER] Enable connection tracking flow accounting
			0 to disable accounting
			1 to enable accounting
			Default value is 0.

	nfsaddrs=	[NFS] Deprecated.  Use ip= instead.
			See Documentation/filesystems/nfs/nfsroot.txt.

	nfsroot=	[NFS] nfs root filesystem for disk-less boxes.
			See Documentation/filesystems/nfs/nfsroot.txt.

	nfsrootdebug	[NFS] enable nfsroot debugging messages.
			See Documentation/filesystems/nfs/nfsroot.txt.

	nfs.callback_tcpport=
			[NFS] set the TCP port on which the NFSv4 callback
			channel should listen.

	nfs.cache_getent=
			[NFS] sets the pathname to the program which is used
			to update the NFS client cache entries.

	nfs.cache_getent_timeout=
			[NFS] sets the timeout after which an attempt to
			update a cache entry is deemed to have failed.

	nfs.idmap_cache_timeout=
			[NFS] set the maximum lifetime for idmapper cache
			entries.

	nfs.enable_ino64=
			[NFS] enable 64-bit inode numbers.
			If zero, the NFS client will fake up a 32-bit inode
			number for the readdir() and stat() syscalls instead
			of returning the full 64-bit number.
			The default is to return 64-bit inode numbers.

	nfs.max_session_slots=
			[NFSv4.1] Sets the maximum number of session slots
			the client will attempt to negotiate with the server.
			This limits the number of simultaneous RPC requests
			that the client can send to the NFSv4.1 server.
			Note that there is little point in setting this
			value higher than the max_tcp_slot_table_limit.

	nfs.nfs4_disable_idmapping=
			[NFSv4] When set to the default of '1', this option
			ensures that both the RPC level authentication
			scheme and the NFS level operations agree to use
			numeric uids/gids if the mount is using the
			'sec=sys' security flavour. In effect it is
			disabling idmapping, which can make migration from
			legacy NFSv2/v3 systems to NFSv4 easier.
			Servers that do not support this mode of operation
			will be autodetected by the client, and it will fall
			back to using the idmapper.
			To turn off this behaviour, set the value to '0'.

	nfs.recover_lost_locks =
			[NFSv4] Attempt to recover locks that were lost due
			to a lease timeout on the server. Please note that
			doing this risks data corruption, since there are
			no guarantees that the file will remain unchanged
			after the locks are lost.
			If you want to enable the kernel legacy behaviour of
			attempting to recover these locks, then set this
			parameter to '1'.
			The default parameter value of '0' causes the kernel
			not to attempt recovery of lost locks.

	nfsd.nfs4_disable_idmapping=
			[NFSv4] Defaults to 0.  When set to '1', the NFSv4
			server will return only numeric uids and gids to
			clients using auth_sys, and will accept numeric uids
			and gids from such clients.  This is intended to ease
			migration from NFSv2/v3.

	nmi_debug=	[KNL,AVR32,SH] Specify one or more actions to take
			when a NMI is triggered.
			Format: [state][,regs][,debounce][,die]

	nmi_watchdog=	[KNL,BUGS=X86] Debugging features for SMP kernels
			Format: [panic,][nopanic,][num]
			Valid num: 0
			0 - turn nmi_watchdog off
			When panic is specified, panic when an NMI watchdog
			timeout occurs (or 'nopanic' to override the opposite
			default).
			This is useful when you use a panic=... timeout and
			need the box quickly up again.

	netpoll.carrier_timeout=
			[NET] Specifies amount of time (in seconds) that
			netpoll should wait for a carrier. By default netpoll
			waits 4 seconds.

	no387		[BUGS=X86-32] Tells the kernel to use the 387 maths
			emulation library even if a 387 maths coprocessor
			is present.

	no_console_suspend
			[HW] Never suspend the console
			Disable suspending of consoles during suspend and
			hibernate operations.  Once disabled, debugging
			messages can reach various consoles while the rest
			of the system is being put to sleep (ie, while
			debugging driver suspend/resume hooks).  This may
			not work reliably with all consoles, but is known
			to work with serial and VGA consoles.

	noaliencache	[MM, NUMA, SLAB] Disables the allocation of alien
			caches in the slab allocator.  Saves per-node memory,
			but will impact performance.

	noalign		[KNL,ARM]

	noapic		[SMP,APIC] Tells the kernel to not make use of any
			IOAPICs that may be present in the system.

	autogroup	Enable scheduler automatic task group creation.

	nobats		[PPC] Do not use BATs for mapping kernel lowmem
			on "Classic" PPC cores.

	nocache		[ARM]

	noclflush	[BUGS=X86] Don't use the CLFLUSH instruction

	nodelayacct	[KNL] Disable per-task delay accounting

	nodisconnect	[HW,SCSI,M68K] Disables SCSI disconnects.

	nodsp		[SH] Disable hardware DSP at boot time.

	noefi		[X86] Disable EFI runtime services support.

	noexec		[IA-64]

	noexec		[X86]
			On X86-32 available only on PAE configured kernels.
			noexec=on: enable non-executable mappings (default)
			noexec=off: disable non-executable mappings

	nosmep		[X86]
			Disable SMEP (Supervisor Mode Execution Protection)
			even if it is supported by processor.

	noexec32	[X86-64]
			This affects only 32-bit executables.
			noexec32=on: enable non-executable mappings (default)
				read doesn't imply executable mappings
			noexec32=off: disable non-executable mappings
				read implies executable mappings

	nofpu		[SH] Disable hardware FPU at boot time.

	nofxsr		[BUGS=X86-32] Disables x86 floating point extended
			register save and restore. The kernel will only save
			legacy floating-point registers on task switch.

	noxsave		[BUGS=X86] Disables x86 extended register state save
			and restore using xsave. The kernel will fallback to
			enabling legacy floating-point and sse state.

	nohlt		[BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
			wfi(ARM) instruction doesn't work correctly and not to
			use it. This is also useful when using JTAG debugger.

	no-hlt		[BUGS=X86-32] Tells the kernel that the hlt
			instruction doesn't work correctly and not to
			use it.

	no_file_caps	Tells the kernel not to honor file capabilities.  The
			only way then for a file to be executed with privilege
			is to be setuid root or executed by root.

	nohalt		[IA-64] Tells the kernel not to use the power saving
			function PAL_HALT_LIGHT when idle. This increases
			power-consumption. On the positive side, it reduces
			interrupt wake-up latency, which may improve performance
			in certain environments such as networked servers or
			real-time systems.

	nohz=		[KNL] Boottime enable/disable dynamic ticks
			Valid arguments: on, off
			Default: on

	noiotrap	[SH] Disables trapped I/O port accesses.

	noirqdebug	[X86-32] Disables the code which attempts to detect and
			disable unhandled interrupt sources.

	no_timer_check	[X86,APIC] Disables the code which tests for
			broken timer IRQ sources.

	noisapnp	[ISAPNP] Disables ISA PnP code.

	noinitrd	[RAM] Tells the kernel not to load any configured
			initial RAM disk.

	nointremap	[X86-64, Intel-IOMMU] Do not enable interrupt
			remapping.
			[Deprecated - use intremap=off]

	nointroute	[IA-64]

	nojitter	[IA64] Disables jitter checking for ITC timers.

	nolapic		[X86-32,APIC] Do not enable or use the local APIC.

	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.

	noltlbs		[PPC] Do not use large page/tlb entries for kernel
			lowmem mapping on PPC40x.

	nomca		[IA-64] Disable machine check abort handling

	nomce		[X86-32] Machine Check Exception

	nomfgpt		[X86-32] Disable Multi-Function General Purpose
			Timer usage (for AMD Geode machines).

	norandmaps	Don't use address space randomization.  Equivalent to
			echo 0 > /proc/sys/kernel/randomize_va_space

	noreplace-paravirt	[X86-32,PV_OPS] Don't patch paravirt_ops

	noreplace-smp	[X86-32,SMP] Don't replace SMP instructions
			with UP alternatives

	noresidual	[PPC] Don't use residual data on PReP machines.

	nordrand	[X86] Disable the direct use of the RDRAND
			instruction even if it is supported by the
			processor.  RDRAND is still available to user
			space applications.

	noresume	[SWSUSP] Disables resume and restores original swap
			space.

	no-scroll	[VGA] Disables scrollback.
			This is required for the Braillex ib80-piezo Braille
			reader made by F.H. Papenmeier (Germany).

	nosbagart	[IA-64]

	nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.

	nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
			and disable the IO APIC.  legacy for "maxcpus=0".

	nosoftlockup	[KNL] Disable the soft-lockup detector.

	noswapaccount	[KNL] Disable accounting of swap in memory resource
			controller. (See Documentation/cgroups/memory.txt)

	nosync		[HW,M68K] Disables sync negotiation for all devices.

	notsc		[BUGS=X86-32] Disable Time Stamp Counter

	nousb		[USB] Disable the USB subsystem

	nowatchdog	[KNL] Disable the lockup detector (NMI watchdog).

	nowb		[ARM]

	nox2apic	[X86-64,APIC] Do not enable x2APIC mode.

	nptcg=		[IA64] Override max number of concurrent global TLB
			purges which is reported from either PAL_VM_SUMMARY or
			SAL PALO.

	nr_cpus=	[SMP] Maximum number of processors that	an SMP kernel
			could support.  nr_cpus=n : n >= 1 limits the kernel to
			supporting 'n' processors. Later in runtime you can not
			use hotplug cpu feature to put more cpu back to online.
			just like you compile the kernel NR_CPUS=n

	nr_uarts=	[SERIAL] maximum number of UARTs to be registered.

	numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
			one of ['zone', 'node', 'default'] can be specified
			This can be set from sysctl after boot.
			See Documentation/sysctl/vm.txt for details.

	ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.
			See Documentation/debugging-via-ohci1394.txt for more
			info.

	olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
			Rather than timing out after 20 ms if an EC
			command is not properly ACKed, override the length
			of the timeout.  We have interrupts disabled while
			waiting for the ACK, so if this is set too high
			interrupts *may* be lost!

	OMGZOMBIES	BRRRAAAAAAIIIIINNNNNSSSSSSSS

	opl3=		[HW,OSS]
			Format: <io>

	oprofile.timer=	[HW]
			Use timer interrupt instead of performance counters

	oprofile.cpu_type=	Force an oprofile cpu type
			This might be useful if you have an older oprofile
			userland or if you want common events.
			Format: { arch_perfmon }
			arch_perfmon: [X86] Force use of architectural
				perfmon on Intel CPUs instead of the
				CPU specific event set.

	osst=		[HW,SCSI] SCSI Tape Driver
			Format: <buffer_size>,<write_threshold>
			See also Documentation/scsi/st.txt.

	panic=		[KNL] Kernel behaviour on panic
			Format: <timeout>

	panic_on_warn	panic() instead of WARN().  Useful to cause kdump
			on a WARN().

	parkbd.port=	[HW] Parallel port number the keyboard adapter is
			connected to, default is 0.
			Format: <parport#>
	parkbd.mode=	[HW] Parallel port keyboard adapter mode of operation,
			0 for XT, 1 for AT (default is AT).
			Format: <mode>

	parport=	[HW,PPT] Specify parallel ports. 0 disables.
			Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
			Use 'auto' to force the driver to use any
			IRQ/DMA settings detected (the default is to
			ignore detected IRQ/DMA settings because of
			possible conflicts). You can specify the base
			address, IRQ, and DMA settings; IRQ and DMA
			should be numbers, or 'auto' (for using detected
			settings on that particular port), or 'nofifo'
			(to avoid using a FIFO even if it is detected).
			Parallel ports are assigned in the order they
			are specified on the command line, starting
			with parport0.

	parport_init_mode=	[HW,PPT]
			Configure VIA parallel port to operate in
			a specific mode. This is necessary on Pegasos
			computer where firmware has no options for setting
			up parallel port mode and sets it to spp.
			Currently this function knows 686a and 8231 chips.
			Format: [spp|ps2|epp|ecp|ecpepp]

	pas2=		[HW,OSS] Format:
			<io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>

	pas16=		[HW,SCSI]
			See header of drivers/scsi/pas16.c.

	pause_on_oops=
			Halt all CPUs after the first oops has been printed for
			the specified number of seconds.  This is to be used if
			your oopses keep scrolling off the screen.

	pcbit=		[HW,ISDN]

	pcd.		[PARIDE]
			See header of drivers/block/paride/pcd.c.
			See also Documentation/blockdev/paride.txt.

	pci=option[,option...]	[PCI] various PCI subsystem options:
		earlydump	[X86] dump PCI config space before the kernel
			        changes anything
		off		[X86] don't probe for the PCI bus
		bios		[X86-32] force use of PCI BIOS, don't access
				the hardware directly. Use this if your machine
				has a non-standard PCI host bridge.
		nobios		[X86-32] disallow use of PCI BIOS, only direct
				hardware access methods are allowed. Use this
				if you experience crashes upon bootup and you
				suspect they are caused by the BIOS.
		conf1		[X86] Force use of PCI Configuration
				Mechanism 1.
		conf2		[X86] Force use of PCI Configuration
				Mechanism 2.
		noaer		[PCIE] If the PCIEAER kernel config parameter is
				enabled, this kernel boot option can be used to
				disable the use of PCIE advanced error reporting.
		nodomains	[PCI] Disable support for multiple PCI
				root domains (aka PCI segments, in ACPI-speak).
		nommconf	[X86] Disable use of MMCONFIG for PCI
				Configuration
		check_enable_amd_mmconf [X86] check for and enable
				properly configured MMIO access to PCI
				config space on AMD family 10h CPU
		msi		[MSI] If the PCI_MSI kernel config parameter is
				enabled, this kernel boot option can be used to
				enable the use of MSI interrupts system-wide.
		nomsi		[MSI] If the PCI_MSI kernel config parameter is
				enabled, this kernel boot option can be used to
				disable the use of MSI interrupts system-wide.
		noioapicquirk	[APIC] Disable all boot interrupt quirks.
				Safety option to keep boot IRQs enabled. This
				should never be necessary.
		ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
				primary IO-APIC for bridges that cannot disable
				boot IRQs. This fixes a source of spurious IRQs
				when the system masks IRQs.
		noioapicreroute	[APIC] Disable workaround that uses the
				boot IRQ equivalent of an IRQ that connects to
				a chipset where boot IRQs cannot be disabled.
				The opposite of ioapicreroute.
		biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
				routing table. These calls are known to be buggy
				on several machines and they hang the machine
				when used, but on other computers it's the only
				way to get the interrupt routing table. Try
				this option if the kernel is unable to allocate
				IRQs or discover secondary PCI buses on your
				motherboard.
		rom		[X86] Assign address space to expansion ROMs.
				Use with caution as certain devices share
				address decoders between ROMs and other
				resources.
		norom		[X86] Do not assign address space to
				expansion ROMs that do not already have
				BIOS assigned address ranges.
		nobar		[X86] Do not assign address space to the
				BARs that weren't assigned by the BIOS.
		irqmask=0xMMMM	[X86] Set a bit mask of IRQs allowed to be
				assigned automatically to PCI devices. You can
				make the kernel exclude IRQs of your ISA cards
				this way.
		pirqaddr=0xAAAAA	[X86] Specify the physical address
				of the PIRQ table (normally generated
				by the BIOS) if it is outside the
				F0000h-100000h range.
		lastbus=N	[X86] Scan all buses thru bus #N. Can be
				useful if the kernel is unable to find your
				secondary buses and you want to tell it
				explicitly which ones they are.
		assign-busses	[X86] Always assign all PCI bus
				numbers ourselves, overriding
				whatever the firmware may have done.
		usepirqmask	[X86] Honor the possible IRQ mask stored
				in the BIOS $PIR table. This is needed on
				some systems with broken BIOSes, notably
				some HP Pavilion N5400 and Omnibook XE3
				notebooks. This will have no effect if ACPI
				IRQ routing is enabled.
		noacpi		[X86] Do not use ACPI for IRQ routing
				or for PCI scanning.
		use_crs		[X86] Use PCI host bridge window information
				from ACPI.  On BIOSes from 2008 or later, this
				is enabled by default.  If you need to use this,
				please report a bug.
		nocrs		[X86] Ignore PCI host bridge windows from ACPI.
			        If you need to use this, please report a bug.
		routeirq	Do IRQ routing for all PCI devices.
				This is normally done in pci_enable_device(),
				so this option is a temporary workaround
				for broken drivers that don't call it.
		skip_isa_align	[X86] do not align io start addr, so can
				handle more pci cards
		firmware	[ARM] Do not re-enumerate the bus but instead
				just use the configuration from the
				bootloader. This is currently used on
				IXP2000 systems where the bus has to be
				configured a certain way for adjunct CPUs.
		noearly		[X86] Don't do any early type 1 scanning.
				This might help on some broken boards which
				machine check when some devices' config space
				is read. But various workarounds are disabled
				and some IOMMU drivers will not work.
		bfsort		Sort PCI devices into breadth-first order.
				This sorting is done to get a device
				order compatible with older (<= 2.4) kernels.
		nobfsort	Don't sort PCI devices into breadth-first order.
		pcie_bus_tune_off	Disable PCIe MPS (Max Payload Size)
				tuning and use the BIOS-configured MPS defaults.
		pcie_bus_safe	Set every device's MPS to the largest value
				supported by all devices below the root complex.
		pcie_bus_perf	Set device MPS to the largest allowable MPS
				based on its parent bus. Also set MRRS (Max
				Read Request Size) to the largest supported
				value (no larger than the MPS that the device
				or bus can support) for best performance.
		pcie_bus_peer2peer	Set every device's MPS to 128B, which
				every device is guaranteed to support. This
				configuration allows peer-to-peer DMA between
				any pair of devices, possibly at the cost of
				reduced performance.  This also guarantees
				that hot-added devices will work.
		cbiosize=nn[KMG]	The fixed amount of bus space which is
				reserved for the CardBus bridge's IO window.
				The default value is 256 bytes.
		cbmemsize=nn[KMG]	The fixed amount of bus space which is
				reserved for the CardBus bridge's memory
				window. The default value is 64 megabytes.
		resource_alignment=
				Format:
				[<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
				Specifies alignment and device to reassign
				aligned memory resources.
				If <order of align> is not specified,
				PAGE_SIZE is used as alignment.
				PCI-PCI bridge can be specified, if resource
				windows need to be expanded.
		ecrc=		Enable/disable PCIe ECRC (transaction layer
				end-to-end CRC checking).
				bios: Use BIOS/firmware settings. This is the
				the default.
				off: Turn ECRC off
				on: Turn ECRC on.
		realloc=	Enable/disable reallocating PCI bridge resources
				if allocations done by BIOS are too small to
				accommodate resources required by all child
				devices.
				off: Turn realloc off
				on: Turn realloc on.
		realloc		same as realloc=on
		nosriov		[HW]
				Disable SRIOV support in kernel.
				Please report a bug if you use this parameter.
		sriov		[HW]
				Enable SRIOV support in kernel.
		noari		do not use PCIe ARI.

	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
			Management.
		off	Disable ASPM.
		force	Enable ASPM even on devices that claim not to support it.
			WARNING: Forcing ASPM on may cause system lockups.

	pcie_hp=	[PCIE] PCI Express Hotplug driver options:
		nomsi	Do not use MSI for PCI Express Native Hotplug (this
			makes all PCIe ports use INTx for hotplug services).

	pcie_ports=	[PCIE] PCIe ports handling:
		compat	Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
			ports driver.

	pcmv=		[HW,PCMCIA] BadgePAD 4

	pd.		[PARIDE]
			See Documentation/blockdev/paride.txt.

	pdcchassis=	[PARISC,HW] Disable/Enable PDC Chassis Status codes at
			boot time.
			Format: { 0 | 1 }
			See arch/parisc/kernel/pdc_chassis.c

	percpu_alloc=	Select which percpu first chunk allocator to use.
			Currently supported values are "embed" and "page".
			Archs may support subset or none of the	selections.
			See comments in mm/percpu.c for details on each
			allocator.  This parameter is primarily	for debugging
			and performance comparison.

	pf.		[PARIDE]
			See Documentation/blockdev/paride.txt.

	pg.		[PARIDE]
			See Documentation/blockdev/paride.txt.

	physefi		[X86] Run EFI in physical mode rather than virtual
			mode.

	pirq=		[SMP,APIC] Manual mp-table setup
			See Documentation/x86/i386/IO-APIC.txt.

	plip=		[PPT,NET] Parallel port network link
			Format: { parport<nr> | timid | 0 }
			See also Documentation/parport.txt.

	pmtmr=		[X86] Manual setup of pmtmr I/O Port. 
			Override pmtimer IOPort with a hex value.
			e.g. pmtmr=0x508

	pnp.debug	[PNP]
			Enable PNP debug messages.  This depends on the
			CONFIG_PNP_DEBUG_MESSAGES option.

	pnpacpi=	[ACPI]
			{ off }

	pnpbios=	[ISAPNP]
			{ on | off | curr | res | no-curr | no-res }

	pnp_reserve_irq=
			[ISAPNP] Exclude IRQs for the autoconfiguration

	pnp_reserve_dma=
			[ISAPNP] Exclude DMAs for the autoconfiguration

	pnp_reserve_io=	[ISAPNP] Exclude I/O ports for the autoconfiguration
			Ranges are in pairs (I/O port base and size).

	pnp_reserve_mem=
			[ISAPNP] Exclude memory regions for the
			autoconfiguration.
			Ranges are in pairs (memory base and size).

	ports=		[IP_VS_FTP] IPVS ftp helper module
			Default is 21.
			Up to 8 (IP_VS_APP_MAX_PORTS) ports
			may be specified.
			Format: <port>,<port>....

	print-fatal-signals=
			[KNL] debug: print fatal signals
			print-fatal-signals=1: print segfault info to
			the kernel console.
			default: off.

	printk.always_kmsg_dump=
			Trigger kmsg_dump for cases other than kernel oops or
			panics
			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)
			default: disabled

	printk.time=	Show timing data prefixed to each printk message line
			Format: <bool>  (1/Y/y=enable, 0/N/n=disable)

	processor.max_cstate=	[HW,ACPI]
			Limit processor to maximum C-state
			max_cstate=9 overrides any DMI blacklist limit.

	processor.nocst	[HW,ACPI]
			Ignore the _CST method to determine C-states,
			instead using the legacy FADT method

	profile=	[KNL] Enable kernel profiling via /proc/profile
			Format: [schedule,]<number>
			Param: "schedule" - profile schedule points.
			Param: <number> - step/bucket size as a power of 2 for
				statistical time based profiling.
			Param: "sleep" - profile D-state sleeping (millisecs).
				Requires CONFIG_SCHEDSTATS
			Param: "kvm" - profile VM exits.

	prompt_ramdisk=	[RAM] List of RAM disks to prompt for floppy disk
			before loading.
			See Documentation/blockdev/ramdisk.txt.

	psmouse.proto=	[HW,MOUSE] Highest PS2 mouse protocol extension to
			probe for; one of (bare|imps|exps|lifebook|any).
	psmouse.rate=	[HW,MOUSE] Set desired mouse report rate, in reports
			per second.
	psmouse.resetafter=	[HW,MOUSE]
			Try to reset the device after so many bad packets
			(0 = never).
	psmouse.resolution=
			[HW,MOUSE] Set desired mouse resolution, in dpi.
	psmouse.smartscroll=
			[HW,MOUSE] Controls Logitech smartscroll autorepeat.
			0 = disabled, 1 = enabled (default).

	pss=		[HW,OSS] Personal Sound System (ECHO ESC614)
			Format:
			<io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>

	pstore.backend=	Specify the name of the pstore backend to use

	pt.		[PARIDE]
			See Documentation/blockdev/paride.txt.

	pty.legacy_count=
			[KNL] Number of legacy pty's. Overwrites compiled-in
			default number.

	quiet		[KNL] Disable most log messages

	quirk_i82576_sriov
			[RHEL6: HW, PCI]
			Quirk for defaulting to old Flash Memory Space for
			pre-production SRIOV NIC hardware.  If you require this
			on production hardware, please contact your hardware
			vendor for a BIOS update.

	r128=		[HW,DRM]

	raid=		[HW,RAID]
			See Documentation/md.txt.

	ramdisk_blocksize=	[RAM]
			See Documentation/blockdev/ramdisk.txt.

	ramdisk_size=	[RAM] Sizes of RAM disks in kilobytes
			See Documentation/blockdev/ramdisk.txt.

	rcupdate.blimit=	[KNL,BOOT]
			Set maximum number of finished RCU callbacks to process
			in one batch.

	rcupdate.qhimark=	[KNL,BOOT]
			Set threshold of queued
			RCU callbacks over which batch limiting is disabled.

	rcupdate.qlowmark=	[KNL,BOOT]
			Set threshold of queued RCU callbacks below which
			batch limiting is re-enabled.

	rdinit=		[KNL]
			Format: <full_path>
			Run specified binary instead of /init from the ramdisk,
			used for early userspace startup. See initrd.

	reboot=		[BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
			Format: <reboot_mode>[,<reboot_mode2>[,...]]
			See arch/*/kernel/reboot.c or arch/*/kernel/process.c

	relax_domain_level=
			[KNL, SMP] Set scheduler's default relax_domain_level.
			See Documentation/cgroups/cpusets.txt.

	reserve=	[KNL,BUGS] Force the kernel to ignore some iomem area

	reservetop=	[X86-32]
			Format: nn[KMG]
			Reserves a hole at the top of the kernel virtual
			address space.

	reset_devices	[KNL] Force drivers to reset the underlying device
			during initialization.

	resume=		[SWSUSP]
			Specify the partition device for software suspend

	resume_offset=	[SWSUSP]
			Specify the offset from the beginning of the partition
			given by "resume=" at which the swap header is located,
			in <PAGE_SIZE> units (needed only for swap files).
			See  Documentation/power/swsusp-and-swap-files.txt

	retain_initrd	[RAM] Keep initrd memory after extraction

	rhash_entries=	[KNL,NET]
			Set number of hash buckets for route cache

	riscom8=	[HW,SERIAL]
			Format: <io_board1>[,<io_board2>[,...<io_boardN>]]

	ro		[KNL] Mount root device read-only on boot

	root=		[KNL] Root filesystem

	rootdelay=	[KNL] Delay (in seconds) to pause before attempting to
			mount the root filesystem

	rootflags=	[KNL] Set root filesystem mount option string

	rootfstype=	[KNL] Set root filesystem type

	rootwait	[KNL] Wait (indefinitely) for root device to show up.
			Useful for devices that are detected asynchronously
			(e.g. USB and MMC devices).

	root_plug.vendor_id=
			[ROOTPLUG] Override the default vendor ID

	root_plug.product_id=
			[ROOTPLUG] Override the default product ID

	root_plug.debug=
			[ROOTPLUG] Enable debugging output

	rw		[KNL] Mount root device read-write on boot

	S		[KNL] Run init in single mode

	sa1100ir	[NET]
			See drivers/net/irda/sa1100_ir.c.

	sbni=		[NET] Granch SBNI12 leased line adapter

	sched_debug	[KNL] Enables verbose scheduler debug messages.

	sc1200wdt=	[HW,WDT] SC1200 WDT (watchdog) driver
			Format: <io>[,<timeout>[,<isapnp>]]

	scsi_debug_*=	[SCSI]
			See drivers/scsi/scsi_debug.c.

	scsi_default_dev_flags=
			[SCSI] SCSI default device flags
			Format: <integer>

	scsi_dev_flags=	[SCSI] Black/white list entry for vendor and model
			Format: <vendor>:<model>:<flags>
			(flags are integer value)

	scsi_logging_level=	[SCSI] a bit mask of logging levels
			See drivers/scsi/scsi_logging.h for bits.  Also
			settable via sysctl at dev.scsi.logging_level
			(/proc/sys/dev/scsi/logging_level).
			There is also a nice 'scsi_logging_level' script in the
			S390-tools package, available for download at
			http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html

	scsi_mod.scan=	[SCSI] sync (default) scans SCSI busses as they are
			discovered.  async scans them in kernel threads,
			allowing boot to proceed.  none ignores them, expecting
			user space to do the scan.

	security=	[SECURITY] Choose a security module to enable at boot.
			If this boot parameter is not specified, only the first
			security module asking for security registration will be
			loaded. An invalid security module name will be treated
			as if no module has been chosen.

	selinux=	[SELINUX] Disable or enable SELinux at boot time.
			Format: { "0" | "1" }
			See security/selinux/Kconfig help text.
			0 -- disable.
			1 -- enable.
			Default value is set via kernel config option.
			If enabled at boot time, /selinux/disable can be used
			later to disable prior to initial policy load.

	serialnumber	[BUGS=X86-32]

	shapers=	[NET]
			Maximal number of shapers.

	show_msr=	[x86] show boot-time MSR settings
			Format: { <integer> }
			Show boot-time (BIOS-initialized) MSR settings.
			The parameter means the number of CPUs to show,
			for example 1 means boot CPU only.

	sim710=		[SCSI,HW]
			See header of drivers/scsi/sim710.c.

	simeth=		[IA-64]
	simscsi=

	slram=		[HW,MTD]

	slub_debug[=options[,slabs]]	[MM, SLUB]
			Enabling slub_debug allows one to determine the
			culprit if slab objects become corrupted. Enabling
			slub_debug can create guard zones around objects and
			may poison objects when not in use. Also tracks the
			last alloc / free. For more information see
			Documentation/vm/slub.txt.

	slub_max_order= [MM, SLUB]
			Determines the maximum allowed order for slabs.
			A high setting may cause OOMs due to memory
			fragmentation. For more information see
			Documentation/vm/slub.txt.

	slub_min_objects=	[MM, SLUB]
			The minimum number of objects per slab. SLUB will
			increase the slab order up to slub_max_order to
			generate a sufficiently large slab able to contain
			the number of objects indicated. The higher the number
			of objects the smaller the overhead of tracking slabs
			and the less frequently locks need to be acquired.
			For more information see Documentation/vm/slub.txt.

	slub_min_order=	[MM, SLUB]
			Determines the mininum page order for slabs. Must be
			lower than slub_max_order.
			For more information see Documentation/vm/slub.txt.

	slub_nomerge	[MM, SLUB]
			Disable merging of slabs with similar size. May be
			necessary if there is some reason to distinguish
			allocs to different slabs. Debug options disable
			merging on their own.
			For more information see Documentation/vm/slub.txt.

	smart2=		[HW]
			Format: <io1>[,<io2>[,...,<io8>]]

	smbios_26_uuid  [X86] Display UUID in SMBIOS 2.6 format

	smp-alt-boot	[X86-32,SMP] On a hotplug CPU system, only
			attempt to substitute SMP alternatives once at boot.

	smsc-ircc2.nopnp	[HW] Don't use PNP to discover SMC devices
	smsc-ircc2.ircc_cfg=	[HW] Device configuration I/O port
	smsc-ircc2.ircc_sir=	[HW] SIR base I/O port
	smsc-ircc2.ircc_fir=	[HW] FIR base I/O port
	smsc-ircc2.ircc_irq=	[HW] IRQ line
	smsc-ircc2.ircc_dma=	[HW] DMA channel
	smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
				0: Toshiba Satellite 1800 (GP data pin select)
				1: Fast pin select (default)
				2: ATC IRMode

	snd-ad1816a=	[HW,ALSA]

	snd-ad1848=	[HW,ALSA]

	snd-ali5451=	[HW,ALSA]

	snd-als100=	[HW,ALSA]

	snd-als4000=	[HW,ALSA]

	snd-azt2320=	[HW,ALSA]

	snd-cmi8330=	[HW,ALSA]

	snd-cmipci=	[HW,ALSA]

	snd-cs4231=	[HW,ALSA]

	snd-cs4232=	[HW,ALSA]

	snd-cs4236=	[HW,ALSA]

	snd-cs4281=	[HW,ALSA]

	snd-cs46xx=	[HW,ALSA]

	snd-dt019x=	[HW,ALSA]

	snd-dummy=	[HW,ALSA]

	snd-emu10k1=	[HW,ALSA]

	snd-ens1370=	[HW,ALSA]

	snd-ens1371=	[HW,ALSA]

	snd-es968=	[HW,ALSA]

	snd-es1688=	[HW,ALSA]

	snd-es18xx=	[HW,ALSA]

	snd-es1938=	[HW,ALSA]

	snd-es1968=	[HW,ALSA]

	snd-fm801=	[HW,ALSA]

	snd-gusclassic=	[HW,ALSA]

	snd-gusextreme=	[HW,ALSA]

	snd-gusmax=	[HW,ALSA]

	snd-hdsp=	[HW,ALSA]

	snd-ice1712=	[HW,ALSA]

	snd-intel8x0=	[HW,ALSA]

	snd-interwave=	[HW,ALSA]

	snd-interwave-stb=
			[HW,ALSA]

	snd-korg1212=	[HW,ALSA]

	snd-maestro3=	[HW,ALSA]

	snd-mpu401=	[HW,ALSA]

	snd-mtpav=	[HW,ALSA]

	snd-nm256=	[HW,ALSA]

	snd-opl3sa2=	[HW,ALSA]

	snd-opti92x-ad1848=
			[HW,ALSA]

	snd-opti92x-cs4231=
			[HW,ALSA]

	snd-opti93x=	[HW,ALSA]

	snd-pmac=	[HW,ALSA]

	snd-rme32=	[HW,ALSA]

	snd-rme96=	[HW,ALSA]

	snd-rme9652=	[HW,ALSA]

	snd-sb8=	[HW,ALSA]

	snd-sb16=	[HW,ALSA]

	snd-sbawe=	[HW,ALSA]

	snd-serial=	[HW,ALSA]

	snd-sgalaxy=	[HW,ALSA]

	snd-sonicvibes=	[HW,ALSA]

	snd-sun-amd7930=
			[HW,ALSA]

	snd-sun-cs4231=	[HW,ALSA]

	snd-trident=	[HW,ALSA]

	snd-usb-audio=	[HW,ALSA,USB]

	snd-via82xx=	[HW,ALSA]

	snd-virmidi=	[HW,ALSA]

	snd-wavefront=	[HW,ALSA]

	snd-ymfpci=	[HW,ALSA]

	softirq_2ms_loop [KNL] Set softirq handling to 2ms maximum.  Default
			 is existing RHEL6 behaviour.

	softlockup_panic=
			[KNL] Should the soft-lockup detector generate panics.

	softlockup_all_cpu_backtrace=
			[KNL] Should the soft-lockup detector generate
			backtraces on all cpus.
			Format: <integer>

	sonypi.*=	[HW] Sony Programmable I/O Control Device driver
			See Documentation/sonypi.txt

	specialix=	[HW,SERIAL] Specialix multi-serial port adapter
			See Documentation/serial/specialix.txt.

	spia_io_base=	[HW,MTD]
	spia_fio_base=
	spia_pedr=
	spia_peddr=

	sscape=		[HW,OSS]
			Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>

	st=		[HW,SCSI] SCSI tape parameters (buffers, etc.)
			See Documentation/scsi/st.txt.

	stacktrace	[FTRACE]
			Enabled the stack tracer on boot up.

	sti=		[PARISC,HW]
			Format: <num>
			Set the STI (builtin display/keyboard on the HP-PARISC
			machines) console (graphic card) which should be used
			as the initial boot-console.
			See also comment in drivers/video/console/sticore.c.

	sti_font=	[HW]
			See comment in drivers/video/console/sticore.c.

	stifb=		[HW]
			Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]

	sunrpc.min_resvport=
	sunrpc.max_resvport=
			[NFS,SUNRPC]
			SunRPC servers often require that client requests
			originate from a privileged port (i.e. a port in the
			range 0 < portnr < 1024).
			An administrator who wishes to reserve some of these
			ports for other uses may adjust the range that the
			kernel's sunrpc client considers to be privileged
			using these two parameters to set the minimum and
			maximum port values.

	sunrpc.pool_mode=
			[NFS]
			Control how the NFS server code allocates CPUs to
			service thread pools.  Depending on how many NICs
			you have and where their interrupts are bound, this
			option will affect which CPUs will do NFS serving.
			Note: this parameter cannot be changed while the
			NFS server is running.

			auto	    the server chooses an appropriate mode
				    automatically using heuristics
			global	    a single global pool contains all CPUs
			percpu	    one pool for each CPU
			pernode	    one pool for each NUMA node (equivalent
				    to global on non-NUMA machines)

	sunrpc.tcp_slot_table_entries=
	sunrpc.udp_slot_table_entries=
			[NFS,SUNRPC]
			Sets the upper limit on the number of simultaneous
			RPC calls that can be sent from the client to a
			server. Increasing these values may allow you to
			improve throughput, but will also increase the
			amount of memory reserved for use by the client.

	swiotlb=	[IA-64] Number of I/O TLB slabs

	switches=	[HW,M68k]

	sym53c416=	[HW,SCSI]
			See header of drivers/scsi/sym53c416.c.

	sysrq_always_enabled
			[KNL]
			Ignore sysrq setting - this boot parameter will
			neutralize any effect of /proc/sys/kernel/sysrq.
			Useful for debugging.

	t128=		[HW,SCSI]
			See header of drivers/scsi/t128.c.

	tdfx=		[HW,DRM]

	test_suspend=	[SUSPEND]
			Specify "mem" (for Suspend-to-RAM) or "standby" (for
			standby suspend) as the system sleep state to briefly
			enter during system startup.  The system is woken from
			this state using a wakeup-capable RTC alarm.

	thash_entries=	[KNL,NET]
			Set number of hash buckets for TCP connection

	thermal.act=	[HW,ACPI]
			-1: disable all active trip points in all thermal zones
			<degrees C>: override all lowest active trip points

	thermal.crt=	[HW,ACPI]
			-1: disable all critical trip points in all thermal zones
			<degrees C>: override all critical trip points

	thermal.nocrt=	[HW,ACPI]
			Set to disable actions on ACPI thermal zone
			critical and hot trip points.

	thermal.off=	[HW,ACPI]
			1: disable ACPI thermal control

	thermal.psv=	[HW,ACPI]
			-1: disable all passive trip points
			<degrees C>: override all passive trip points to this
			value

	thermal.tzp=	[HW,ACPI]
			Specify global default ACPI thermal zone polling rate
			<deci-seconds>: poll all this frequency
			0: no polling (default)

	tmscsim=	[HW,SCSI]
			See comment before function dc390_setup() in
			drivers/scsi/tmscsim.c.

	topology=	[S390]
			Format: {off | on}
			Specify if the kernel should make use of the cpu
			topology informations if the hardware supports these.
			The scheduler will make use of these informations and
			e.g. base its process migration decisions on it.
			Default is on.

	tp720=		[HW,PS2]

	tpm_suspend_pcr=[HW,TPM]
			Format: integer pcr id
			Specify that at suspend time, the tpm driver
			should extend the specified pcr with zeros,
			as a workaround for some chips which fail to
			flush the last written pcr on TPM_SaveState.
			This will guarantee that all the other pcrs
			are saved.

	trace_buf_size=nn[KMG]
			[FTRACE] will set tracing buffer size.

	trace_event=[event-list]
			[FTRACE] Set and start specified trace events in order
			to facilitate early boot debugging.
			See also Documentation/trace/events.txt

	trix=		[HW,OSS] MediaTrix AudioTrix Pro
			Format:
			<io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>

	tsc=		Disable clocksource stability checks for TSC.
			Format: <string>
			[x86] reliable: mark tsc clocksource as reliable, this
			disables clocksource verification at runtime, as well
			as the stability checks done at bootup.	Used to enable
			high-resolution timer mode on older hardware, and in
			virtualized environment.

	tsc_init_debug  [RHEL] Output additional information about the TSC
			during system boot.

	turbografx.map[2|3]=	[HW,JOY]
			TurboGraFX parallel port interface
			Format:
			<port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
			See also Documentation/input/joystick-parport.txt

	u14-34f=	[HW,SCSI] UltraStor 14F/34F SCSI host adapter
			See header of drivers/scsi/u14-34f.c.

	uart401=	[HW,OSS]
			Format: <io>,<irq>

	uart6850=	[HW,OSS]
			Format: <io>,<irq>

	uhci-hcd.ignore_oc=
			[USB] Ignore overcurrent events (default N).
			Some badly-designed motherboards generate lots of
			bogus events, for ports that aren't wired to
			anything.  Set this parameter to avoid log spamming.
			Note that genuine overcurrent events won't be
			reported either.

	unknown_nmi_panic
			[X86]
			Set unknown_nmi_panic=1 early on boot.

	usbcore.autosuspend=
			[USB] The autosuspend time delay (in seconds) used
			for newly-detected USB devices (default 2).  This
			is the time required before an idle device will be
			autosuspended.  Devices for which the delay is set
			to a negative value won't be autosuspended at all.

	usbcore.usbfs_snoop=
			[USB] Set to log all usbfs traffic (default 0 = off).

	usbcore.blinkenlights=
			[USB] Set to cycle leds on hubs (default 0 = off).

	usbcore.old_scheme_first=
			[USB] Start with the old device initialization
			scheme (default 0 = off).

	usbcore.usbfs_memory_mb=
			[USB] Memory limit (in MB) for buffers allocated by
			usbfs (default = 16, 0 = max = 2047).

	usbcore.use_both_schemes=
			[USB] Try the other device initialization scheme
			if the first one fails (default 1 = enabled).

	usbcore.initial_descriptor_timeout=
			[USB] Specifies timeout for the initial 64-byte
                        USB_REQ_GET_DESCRIPTOR request in milliseconds
			(default 5000 = 5.0 seconds).

	usbhid.mousepoll=
			[USBHID] The interval which mice are to be polled at.

	usb-storage.delay_use=
			[UMS] The delay in seconds before a new device is
			scanned for Logical Units (default 5).

	usb-storage.quirks=
			[UMS] A list of quirks entries to supplement or
			override the built-in unusual_devs list.  List
			entries are separated by commas.  Each entry has
			the form VID:PID:Flags where VID and PID are Vendor
			and Product ID values (4-digit hex numbers) and
			Flags is a set of characters, each corresponding
			to a common usb-storage quirk flag as follows:
				a = SANE_SENSE (collect more than 18 bytes
					of sense data);
				b = BAD_SENSE (don't collect more than 18
					bytes of sense data);
				c = FIX_CAPACITY (decrease the reported
					device capacity by one sector);
				h = CAPACITY_HEURISTICS (decrease the
					reported device capacity by one
					sector if the number is odd);
				i = IGNORE_DEVICE (don't bind to this
					device);
				l = NOT_LOCKABLE (don't try to lock and
					unlock ejectable media);
				m = MAX_SECTORS_64 (don't transfer more
					than 64 sectors = 32 KB at a time);
				o = CAPACITY_OK (accept the capacity
					reported by the device);
				r = IGNORE_RESIDUE (the device reports
					bogus residue values);
				s = SINGLE_LUN (the device has only one
					Logical Unit);
				w = NO_WP_DETECT (don't test whether the
					medium is write-protected).
			Example: quirks=0419:aaf5:rl,0421:0433:rc

	userpte=
			[X86] Flags controlling user PTE allocations.

				nohigh = do not allocate PTE pages in
					HIGHMEM regardless of setting
					of CONFIG_HIGHPTE.

	vdso=		[X86,SH]
			vdso=2: enable compat VDSO (default with COMPAT_VDSO)
			vdso=1: enable VDSO (default)
			vdso=0: disable VDSO mapping

	vdso32=		[X86]
			vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
			vdso32=1: enable 32-bit VDSO (default)
			vdso32=0: disable 32-bit VDSO mapping

	vector=		[IA-64,SMP]
			vector=percpu: enable percpu vector domain

	video=		[FB] Frame buffer configuration
			See Documentation/fb/modedb.txt.

	vga=		[BOOT,X86-32] Select a particular video mode
			See Documentation/x86/boot.txt and
			Documentation/svga.txt.
			Use vga=ask for menu.
			This is actually a boot loader parameter; the value is
			passed to the kernel using a special protocol.

	vmalloc=nn[KMG]	[KNL,BOOT] Forces the vmalloc area to have an exact
			size of <nn>. This can be used to increase the
			minimum size (128MB on x86). It can also be used to
			decrease the size and leave more room for directly
			mapped kernel RAM.

	vmhalt=		[KNL,S390] Perform z/VM CP command after system halt.
			Format: <command>

	vmpanic=	[KNL,S390] Perform z/VM CP command after kernel panic.
			Format: <command>

	vmpoff=		[KNL,S390] Perform z/VM CP command after power off.
			Format: <command>

	vt.default_blu=	[VT]
			Format: <blue0>,<blue1>,<blue2>,...,<blue15>
			Change the default blue palette of the console.
			This is a 16-member array composed of values
			ranging from 0-255.

	vt.default_grn=	[VT]
			Format: <green0>,<green1>,<green2>,...,<green15>
			Change the default green palette of the console.
			This is a 16-member array composed of values
			ranging from 0-255.

	vt.default_red=	[VT]
			Format: <red0>,<red1>,<red2>,...,<red15>
			Change the default red palette of the console.
			This is a 16-member array composed of values
			ranging from 0-255.

	vt.default_utf8=
			[VT]
			Format=<0|1>
			Set system-wide default UTF-8 mode for all tty's.
			Default is 1, i.e. UTF-8 mode is enabled for all
			newly opened terminals.

	waveartist=	[HW,OSS]
			Format: <io>,<irq>,<dma>,<dma2>

	wd33c93=	[HW,SCSI]
			See header of drivers/scsi/wd33c93.c.

	wd7000=		[HW,SCSI]
			See header of drivers/scsi/wd7000.c.

	wdt=		[WDT] Watchdog
			See Documentation/watchdog/wdt.txt.

	x2apic_phys	[X86-64,APIC] Use x2apic physical mode instead of
			default x2apic cluster mode on platforms
			supporting x2apic.

	xd=		[HW,XT] Original XT pre-IDE (RLL encoded) disks.
	xd_geo=		See header of drivers/block/xd.c.

	xen_emul_unplug=                [HW,X86,XEN]
			Unplug Xen emulated devices
			Format: [unplug0,][unplug1]
			ide-disks -- unplug primary master IDE devices
			aux-ide-disks -- unplug non-primary-master IDE devices
			nics -- unplug network devices
			all -- unplug all emulated devices (NICs and IDE disks)
			unnecessary -- unplugging emulated devices is
				unnecessary even if the host did not respond to
				the unplug protocol
			never -- do not unplug even if version check succeeds

	xirc2ps_cs=	[NET,PCMCIA]
			Format:
			<irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
______________________________________________________________________

TODO:

	Add documentation for ALSA options.
	Add more DRM drivers.
kernel-parameters
yum install kernel-doc-2.6.32-696.el6.noarch

简单的内核编译流程:(环境:CentOS7.4mini版)

 1、准备:

(1) 准备好开发环境(yum groupinstall -y "Development Tools" ; yum install -y ncurses-devel elfutils-libelf-devel openssl-devel bc)

(2) 获取目标主机上硬件设备的相关信息

(3) 获取目标主机系统功能的相关信息

(4) 获取内核源代码包(www.kernel.org)

 2、解压内核包,进入linux-xxx目录;调试配置文件(.config)

(a) make config:基于命令行以遍历的方式去配置内核中可配置的每个选项

(b) make menuconfig:基于curses的文本窗口界面

(c) make gconfig:基于GTK (GNOME)环境窗口界面

(d) make xconfig:基于QT(KDE)环境的窗口界面,支持“全新配置”模式进行配置

(a) make defconfig:基于内核为目标平台提供的“默认”配置进行配置

(b) make allyesconfig: 所有选项均回答为“yes“

(c) make allnoconfig: 所有选项均回答为“no“

3、编译

  make -j #:全编译,如果我们只需要编译单个模块,那么我们可以cd到子目录或者make /path/MODULS.ko可以实现只对单个模块进行编译

    -j:支持并行编译,#为物理CPU核心数

4、安装模块

  make modules_install

5、安装内核文件,生成initramfs文件并且自动配置grub菜单

  make install

6、reboot启动选择新内核进入系统就完成了

7、如果编译失败需要重新编译我们可以使用以下命令来清理

# make clean:清理大多数编译生成的文件,但会保留config文件等 
# make mrproper: 清理所有编译生成的文件、config及某些备份文件 
# make distclean:mrproper、patches以及编辑器备份文件 

8、如果新的内核有bug需要卸载内核

  1. 删除/lib/modules/目录下不需要的内核库文件
  2. 删除/usr/src/linux/目录下不需要的内核源码
  3. 删除/boot目录下启动的内核和内核映像文件
  4. 更改grub的配置文件,删除不需要的内核启动列表

 /proc:

内核把自己内部状态信息及统计信息,以及可配置参数通过proc伪文件系统加以输出

常见重要参数

/proc/sys/net/ipv4/icmp_echo_ignore_all
/proc/sys/net/ipv4/ip_forward
/proc/sys/net/ipv4/ip_default_ttl
/proc/sys/vm/drop_caches
/proc/sys/net/ipv4/tcp_syn_retries
/proc/sys/net/ipv4/tcp_fin_timeout
/proc/sys/net/ipv4/tcp_syncookies  
/proc/sys/net/ipv4/tcp_max_tw_buckets
/proc/sys/net/ipv4/tcp_max_syn_backlog
/proc/sys/net/ipv4/ip_local_port_range

/sys

sysfs:为用户使用的伪文件系统,输出内核识别出的各硬件设备的相关属性信息,也有内核对硬件特性的设定信息;有些参数是可以修改的,用于调整硬件工作特性。

相关管理工具:

sysctl:修改内核参数的工具

  • -p 重新读入/etc/sysctl.conf
  • -a 列出当前生效的内核参数
  • -w net.ipv4.ip_forward = 1 即时生效

uname

  • -r:显示内核版本号
  • -a:显示全部信息
  • -n:显示主机名

lsmod:显示已经装载的模块

modinfo:显示模块的详细信息

  • -n:显示模块路径
  • -p:显示模块参数
  • -a:显示模块作者
  • -d:显示模块描述信息
  • -l:显示模块的遵循的协议

modprobe:装载模块

  • -r:卸载模块

depmod:内核模块依赖关系文件及系统信息映射文件的生成工具

insmod:指定装载模块文件,但不自动解决依赖模块

rmmod:卸载模块

time cmd 检测命令执行花的时间

lscpu:查看CPU信息

lspci:查看pci相关信息

lsusb:查看usb相关信息

lsblk:查看块设备相关信息

hal-device:查看所有硬件信息(CentOS6.x)

实验:制作mini-linux(环境:CentOS6.9)

为了对linux系统有更多的认识,我们可以基于CentOS的环境自己来在新硬盘上安装一个mini版的linux,只需要提供最基础的程序来运行。

1)准备工作

  1. VMware12虚拟机
  2. CentOS6.9系统
  3. 为系统加一块虚拟硬盘,20G,如果是在虚拟机开机加的硬盘需要扫描一下硬盘:# echo '- - -' > /sys/class/scsi_host/host2/scan 
  4. 一个脚本,方便我们cp命令
#/bin/bash
green_OK() { echo -e "[   \033[1;32mOK\033[0m   ]"; }
red_FAILED() { echo -e  "[ \033[1;31mFAILED\033[0m ]"; }
Screen=`stty -F /dev/tty size`
Columus=${Screen#* }
Spa_Col=$[Columus-16]

success() {
        local i
        string="$1"
        Rt_Spa=$[$Spa_Col-${#string}]
        echo -n "$string"
        for i in `seq $Rt_Spa` ;do
                echo -n "."
                sleep 0.005
        done
        green_OK
}
failed() {
        local i
        string="$1"
        Rt_Spa=$[$Spa_Col-${#string}]
        echo -n "$string"
        for i in `seq $Rt_Spa` ;do
                echo -n " "
        done
        red_FAILED
}

Ddir="/mnt/sysroot"
[ ! -d "$Ddir" ] && mkdir "$Ddir"

cpbin() {
        cmddir=`echo "$Cmd_path" |grep -o ".*/\b"`
        [ ! -d "${Ddir}${cmddir}" ] && mkdir -p "${Ddir}${cmddir}"
        cp -n "$Cmd_path" "${Ddir}${cmddir}"
}

libcp() {
        echo "$Lib_path" |while read line ;do
                libdir=`echo "$line" |grep -o ".*/\b"`
                [ ! -d "${Ddir}${libdir}" ] && mkdir -p "${Ddir}${libdir}"
                cp -n "$line" "${Ddir}${libdir}" 2>/dev/null
        done
}

while read -p "Input a cmd. (quit): " CMD ;do
        if [ "$CMD" == 'quit' ] ;then echo "Think you! Bye bye."; break; fi
        if ! which "$CMD" &>/dev/null ;then 
                echo "not find $CMD or is a shell builtin, please input again!"
                failed "copy $CMD failed."
                continue
        fi
        Cmd_path=`which $CMD |grep -o "/.*"`
        Lib_path=`ldd $Cmd_path |sed -nr 's#.*[[:space:]]+(/.*) .*#\1#p'`
        cpbin
        libcp
        success "copy $CMD Complete."
done
copycmd.sh

2)分区格式化新硬盘并且挂载

  1. sdb1分200M作为boot分区
  2. sdb2分10G作为根分区
  3. 剩下的可以自由分配
[root@rhel6 ~]# mkfs.ext4 /dev/sdb1
[root@rhel6 ~]# mkfs.ext4 /dev/sdb2
[root@rhel6 ~]# mkdir /mnt/sysroot #
[root@rhel6 ~]# mount /dev/sdb2 /mnt/sysroot/
[root@rhel6 ~]# mkdir /mnt/sysroot/boot
[root@rhel6 ~]# mount /dev/sdb1 /mnt/sysroot/boot

3)安装grub,提供内核和ramdisk文件,并且编辑配置文件

[root@rhel6 ~]# grub-install --root-directory=/mnt/sysroot/ /dev/sdb
[root@rhel6 ~]# cp /boot/initramfs-2.6.32-642.el6.x86_64.img /mnt/sysroot/boot/initramfs.img
[root@rhel6 ~]# cp /boot/vmlinuz-2.6.32-642.el6.x86_64 /mnt/sysroot/boot/vmlinuz
[root@rhel6 ~]# cat >/mnt/sysroot/boot/grub/grub.conf <<EOF
default=0
timeout=3
title mini_linux
    root(hd0,0)
    kernel /vmlinuz ro root=UUID=ce79412f-72b8-4313-8a55-5fb734ffacfe selinux=0 init=/bin/bash  #这里是/dev/sdb2(mini_linux的根)的UUID
   initrd /initramfs.img

4)接下来我们就可以把常用的cmd和对应依赖的库文件复制到我们的/mnt/sysroot/下了

[root@rhel6 ~]# mkdir -pv /mnt/sysroot/{bin,dev,etc,home,lib,lib64,media,mnt,opt,proc,root,sbin,sys,usr/{bin,etc,include,lib,lib64,libexec,local,sbin,share,src,tmp},var,tmp}
[root@rhel6 ~]# ./copycmd.sh
Input a cmd. (quit): bash
copy bash Complete................................................................[   OK   ]
Input a cmd. (quit): ifconfig
copy ifconfig Complete............................................................[   OK   ]
Input a cmd. (quit): insmod
copy insmod Complete..............................................................[   OK   ]
Input a cmd. (quit): ping
copy ping Complete................................................................[   OK   ]
Input a cmd. (quit): mount
copy mount Complete...............................................................[   OK   ]
Input a cmd. (quit): ls
copy ls Complete..................................................................[   OK   ]
Input a cmd. (quit): cat
copy cat Complete.................................................................[   OK   ]
Input a cmd. (quit): df
copy df Complete..................................................................[   OK   ]
Input a cmd. (quit): lsblk
copy lsblk Complete...............................................................[   OK   ]
Input a cmd. (quit): blkid
copy blkid Complete...............................................................[   OK   ]
Input a cmd. (quit): vi
copy vi Complete..................................................................[   OK   ]
Input a cmd. (quit): sed
copy sed Complete.................................................................[   OK   ]
Input a cmd. (quit): grep
copy grep Complete................................................................[   OK   ]
Input a cmd. (quit): awk
copy awk Complete.................................................................[   OK   ]
Input a cmd. (quit): quit  
Think you! Bye bye.

5)接下来我们去提供网卡驱动模块

[root@rhel6 ~]# mkdir /mnt/sysroot/lib/modules
[root@rhel6 ~]# cp /lib/modules/2.6.32-642.el6.x86_64/kernel/drivers/net/e1000/e1000.ko /mnt/sysroot/lib/modules 

6)现在一切都完成了,我们接下来关闭虚拟机,在关闭前执行几次sync命令来保证数据同步到磁盘上,然后将我们的mini_linux虚拟磁盘挂到新虚拟机上,调BIOS让其成为第一启动项,启动后将e1000.ko模块装载后就可以使用网络了

insmod /lib/modules/e1000.ko
ifconfig eth0 192.168.222.222 up

个人学习笔记 

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转载自www.cnblogs.com/L-dongf/p/9019415.html