硬件：
核心板 ： Tiny4412-1306-Schematic
底板 ： Tiny4412SDK-1308（没有micro USB）其他都一样参考博客：https://www.cnblogs.com/pengdonglin137/p/5159032.html
在此感谢前辈分享。
代码已上传至github上管理。https://github.com/Jason543716996/tiny4412.git
启动log：
[ 2.218605] s3c-sdhci 12530000.sdhci: clock source 2: mmc_busclk.2 (100000000 Hz)
[ 2.230745] s3c-sdhci 12530000.sdhci: No vqmmc regulator found
[ 2.265442] mmc0: SDHCI controller on samsung-hsmmc [12530000.sdhci] using ADMA
[ 2.518999] mmc0: new high speed SDHC card at address aaaa
[ 2.519718] mmcblk0: mmc0:aaaa SS08G 7.40 GiB
[ 2.521701] mmcblk0: p1 p2查看设备文件：
[root@tiny4412 ]# ls /dev/mmc*
/dev/mmcblk0 /dev/mmcblk0p1 /dev/mmcblk0p2
尝试通过SDMMC启动，设置环境变量
TINY4412 # set bootargs "root=/dev/mmcblk0p2 console=ttySAC0,115200"
TINY4412 # save
Saving Environment to SMDK bootable device...
done
[ 0.157780] usbcore: registered new interface driver usbfs
[ 0.157854] usbcore: registered new interface driver hub
[ 0.157933] usbcore: registered new device driver usb
[ 0.159120] Advanced Linux Sound Architecture Driver Initialized.
[ 0.160192] clocksource: Switched to clocksource mct-frc
[ 0.169772] missing cooling_device property
[ 0.169781] failed to build thermal zone cpu-thermal: -2
[ 0.169878] NET: Registered protocol family 2
[ 0.170263] TCP established hash table entries: 8192 (order: 3, 32768 bytes)
[ 0.170323] TCP bind hash table entries: 8192 (order: 5, 163840 bytes)
[ 0.170439] TCP: Hash tables configured (established 8192 bind 8192)
[ 0.170512] UDP hash table entries: 512 (order: 2, 24576 bytes)
[ 0.170539] UDP-Lite hash table entries: 512 (order: 2, 24576 bytes)
[ 0.170673] NET: Registered protocol family 1
[ 0.170885] RPC: Registered named UNIX socket transport module.
[ 0.170892] RPC: Registered udp transport module.
[ 0.170897] RPC: Registered tcp transport module.
[ 0.170902] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.172276] futex hash table entries: 1024 (order: 4, 65536 bytes)
[ 0.181703] romfs: ROMFS MTD (C) 2007 Red Hat, Inc.
[ 0.182357] bounce: pool size: 64 pages
[ 0.182369] io scheduler noop registered
[ 0.182378] io scheduler deadline registered
[ 0.182546] io scheduler cfq registered (default)
[ 0.183664] 125b0000.exynos-usbphy supply vbus not found, using dummy regulator
[ 0.188049] dma-pl330 12680000.pdma: Loaded driver for PL330 DMAC-141330
[ 0.188059] dma-pl330 12680000.pdma: DBUFF-32x4bytes Num_Chans-8 Num_Peri-32 Num_Events-32
[ 0.191133] dma-pl330 12690000.pdma: Loaded driver for PL330 DMAC-141330
[ 0.191143] dma-pl330 12690000.pdma: DBUFF-32x4bytes Num_Chans-8 Num_Peri-32 Num_Events-32
[ 0.192042] dma-pl330 12850000.mdma: Loaded driver for PL330 DMAC-141330
[ 0.192051] dma-pl330 12850000.mdma: DBUFF-64x8bytes Num_Chans-8 Num_Peri-1 Num_Events-32
[ 0.252055] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
[ 0.253362] 13800000.serial: ttySAC0 at MMIO 0x13800000 (irq = 47, base_baud = 0) is a S3C6400/10
[ 0.871626] console [ttySAC0] enabled
[ 0.875601] 13810000.serial: ttySAC1 at MMIO 0x13810000 (irq = 48, base_baud = 0) is a S3C6400/10
[ 0.884392] 13820000.serial: ttySAC2 at MMIO 0x13820000 (irq = 49, base_baud = 0) is a S3C6400/10
[ 0.893251] 13830000.serial: ttySAC3 at MMIO 0x13830000 (irq = 50, base_baud = 0) is a S3C6400/10
[ 0.902878] [drm] Initialized drm 1.1.0 20060810
[ 0.916799] brd: module loaded
[ 0.921771] loop: module loaded
[ 0.922648] usbcore: registered new interface driver r8152
[ 0.922778] usbcore: registered new interface driver asix
[ 0.923486] usbcore: registered new interface driver ax88179_178a
[ 0.929576] usbcore: registered new interface driver cdc_ether
[ 0.935393] usbcore: registered new interface driver dm9601
[ 0.940962] usbcore: registered new interface driver smsc75xx
[ 0.946687] usbcore: registered new interface driver smsc95xx
[ 0.952398] usbcore: registered new interface driver net1080
[ 0.958040] usbcore: registered new interface driver cdc_subset
[ 0.963941] usbcore: registered new interface driver zaurus
[ 0.969530] usbcore: registered new interface driver cdc_ncm
[ 0.975537] 12480000.hsotg supply vusb_d not found, using dummy regulator
[ 0.981880] 12480000.hsotg supply vusb_a not found, using dummy regulator
[ 1.315233] dwc2 12480000.hsotg: EPs: 16, dedicated fifos, 7808 entries in SPRAM
[ 1.875789] dwc2 12480000.hsotg: DWC OTG Controller
[ 1.875861] dwc2 12480000.hsotg: new USB bus registered, assigned bus number 1
[ 1.875945] dwc2 12480000.hsotg: irq 45, io mem 0x00000000
[ 1.876098] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
[ 1.877793] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 1.885019] usb usb1: Product: DWC OTG Controller
[ 1.889696] usb usb1: Manufacturer: Linux 4.4.0-g58d0198-dirty dwc2_hsotg
[ 1.896466] usb usb1: SerialNumber: 12480000.hsotg
[ 1.901752] hub 1-0:1.0: USB hub found
[ 1.904978] hub 1-0:1.0: 1 port detected
[ 1.909400] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[ 1.915396] ehci-exynos: EHCI EXYNOS driver
[ 1.919997] exynos-ehci 12580000.ehci: EHCI Host Controller
[ 1.925125] exynos-ehci 12580000.ehci: new USB bus registered, assigned bus number 2
[ 1.932973] exynos-ehci 12580000.ehci: irq 46, io mem 0x12580000
[ 1.945217] exynos-ehci 12580000.ehci: USB 2.0 started, EHCI 1.00
[ 1.945370] usb usb2: New USB device found, idVendor=1d6b, idProduct=0002
[ 1.951674] usb usb2: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 1.958876] usb usb2: Product: EHCI Host Controller
[ 1.963736] usb usb2: Manufacturer: Linux 4.4.0-g58d0198-dirty ehci_hcd
[ 1.970332] usb usb2: SerialNumber: 12580000.ehci
[ 1.975466] hub 2-0:1.0: USB hub found
[ 1.978760] hub 2-0:1.0: 3 ports detected
[ 1.983226] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[ 1.988920] ohci-exynos: OHCI EXYNOS driver
[ 1.993198] exynos-ohci 12590000.ohci: USB Host Controller
[ 1.998558] exynos-ohci 12590000.ohci: new USB bus registered, assigned bus number 3
[ 2.006413] exynos-ohci 12590000.ohci: irq 46, io mem 0x12590000
[ 2.069328] usb usb3: New USB device found, idVendor=1d6b, idProduct=0001
[ 2.069394] usb usb3: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 2.069461] usb usb3: Product: USB Host Controller
[ 2.069508] usb usb3: Manufacturer: Linux 4.4.0-g58d0198-dirty ohci_hcd
[ 2.072385] usb usb3: SerialNumber: 12590000.ohci
[ 2.077506] hub 3-0:1.0: USB hub found
[ 2.080886] hub 3-0:1.0: 3 ports detected
[ 2.085539] usbcore: registered new interface driver usb-storage
[ 2.091133] usb4640 usb-hub: switched to HUB mode
[ 2.095474] usb4640 usb-hub: usb4640_probe: probed in hub mode
[ 2.101429] using random self ethernet address
[ 2.105717] using random host ethernet address
[ 2.110605] usb0: HOST MAC f2:06:91:0d:08:28
[ 2.114415] usb0: MAC 86:e6:69:2b:cf:f5
[ 2.118225] using random self ethernet address
[ 2.122643] using random host ethernet address
[ 2.127098] g_ether gadget: Ethernet Gadget, version: Memorial Day 2008
[ 2.133665] g_ether gadget: g_ether ready
[ 2.137805] dwc2 12480000.hsotg: dwc2_hsotg_init_fifo: timeout flushing fifos (GRSTCTL=80000430)
[ 2.148532] dwc2 12480000.hsotg: Failed to get CSftRst asserted
[ 2.152327] dwc2 12480000.hsotg: bound driver g_ether
[ 2.159478] dwc2 12480000.hsotg: Failed to get CSftRst asserted
[ 2.163599] mousedev: PS/2 mouse device common for all mice
[ 2.169582] s3c-rtc 10070000.rtc: failed to find rtc source clock
[ 2.174912] s3c-rtc: probe of 10070000.rtc failed with error -2
[ 2.181236] i2c /dev entries driver
[ 2.186499] device-mapper: ioctl: 4.34.0-ioctl (2015-10-28) initialised: [email protected]
[ 2.193520] sdhci: Secure Digital Host Controller Interface driver
[ 2.198852] sdhci: Copyright(c) Pierre Ossman
[ 2.203466] s3c-sdhci 12530000.sdhci: clock source 2: mmc_busclk.2 (100000000 Hz)
[ 2.210716] s3c-sdhci 12530000.sdhci: Got CD GPIO
[ 2.215606] s3c-sdhci 12530000.sdhci: No vqmmc regulator found
[ 2.250308] mmc0: SDHCI controller on samsung-hsmmc [12530000.sdhci] using ADMA
[ 2.250495] Synopsys Designware Multimedia Card Interface Driver
[ 2.252013] usbcore: registered new interface driver usbhid
[ 2.252067] usbhid: USB HID core driver
[ 2.254573] NET: Registered protocol family 10
[ 2.260691] sit: IPv6 over IPv4 tunneling driver
[ 2.261178] NET: Registered protocol family 17
[ 2.264136] NET: Registered protocol family 15
[ 2.268718] Registering SWP/SWPB emulation handler
[ 2.274262] hctosys: unable to open rtc device (rtc0)
[ 2.290252] usb 2-1: new high-speed USB device number 2 using exynos-ehci
[ 2.290436] ALSA device list:
[ 2.290468] No soundcards found.
[ 2.292201] VFS: Cannot open root device "mmcblk0p2" or unknown-block(0,0): error -6
[ 2.299257] Please append a correct "root=" boot option; here are the available partitions:
[ 2.307573] 0100 8192 ram0 (driver?)
[ 2.312127] 0101 8192 ram1 (driver?)
[ 2.316727] 0102 8192 ram2 (driver?)
[ 2.321332] 0103 8192 ram3 (driver?)
[ 2.325951] 0104 8192 ram4 (driver?)
[ 2.330548] 0105 8192 ram5 (driver?)
[ 2.335131] 0106 8192 ram6 (driver?)
[ 2.339732] 0107 8192 ram7 (driver?)
[ 2.344332] 0108 8192 ram8 (driver?)
[ 2.348933] 0109 8192 ram9 (driver?)
[ 2.353533] 010a 8192 ram10 (driver?)
[ 2.358220] 010b 8192 ram13 (driver?)
[ 2.372282] 010e 8192 ram14 (driver?)
[ 2.376969] 010f 8192 ram15 (driver?)
[ 2.381660] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[ 2.389903] CPU: 2 d_backtrace) from [<c0012e08>] (show_stack+0x10/0x14)
[ 2.410832] [<c0012e08>] (show_stack) from [<c01f6bd8>] (dump_stack+0x80/0xc0)
[ 2.418033] [<c01f6bd8>] (dump_stack) from [<c0097380>] (panic+0xa0/0x210)
[ 2.424893] [<c0097380>] (panic) from [<c07991a0>] (mount_block_root+0x19c/0x238)
[ 2.432352] [<c07991a0>] (mount_block_root) from [<c0799448>] (mount_root+0x120/0x128)
[ 2.440250] [<c0799448>] (mount_root) from [<c07995e0>] (prepare_namespace+0x190/0x1d8)
[ 2.448236] [<c07995e0>] (prepare_namespace) from [<c0798e60>] (kernel_init_freeable+0x1e8/0x1f8)
[ 2.457092] [<c0798e60>] (kernel_init_freeable) from [<c056892c>] (kernel_init+0x8/0xf0)
[ 2.465163] [<c056892c>] (kernel_init) from [<c000f6b8>] (ret_from_fork+0x14/0x3c)
[ 2.465872] usb 2-1: New USB device found, idVendor=1a40, idProduct=0101
[ 2.465881] usb 2-1: New USB device strings: Mfr=0, Product=1, SerialNumber=0
[ 2.465888] usb 2-1: Product: USB 2.0 Hub
[ 2.466693] hub 2-1:1.0: USB hub found
[ 2.466868] hub 2-1:1.0: 4 ports detected
[ 2.498230] CPU1: stopping
[ 2.500921] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.0-g58d0198-dirty #2
[ 2.508033] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[ 2.514124] [<c00160ec>] (unwind_backtrace) from [<c0012e08>] (show_stack+0x10/0x14)
[ 2.521846] [<c0012e08>] (show_stack) from [<c01f6bd8>] (dump_stack+0x80/0xc0)
[ 2.529046] [<c01f6bd8>] (dump_stack) from [<c0015348>] (handle_IPI+0x1ac/0x1c0)
[ 2.536423] [<c0015348>] (handle_IPI) from [<c00094d0>] (gic_handle_irq+0x90/0x94)
[ 2.543974] [<c00094d0>] (gic_handle_irq) from [<c00138d4>] (__irq_svc+0x54/0x90)
[ 2.551434] Exception stack(0xef0aff88 to 0xef0affd0)
[ 2.556473] ff80: 00000001 00000000 ef0affe0 c001b860 c0571388 00000000
[ 2.564634] ffa0: 00000000 c08013c0 c08064b4 c07fe2e4 ef0ae000 c08064bc 00000001 ef0affd8
[ 2.572789] ffc0: c00100f8 c00100fc 60000013 ffffffff
[ 2.577828] [<c00138d4>] (__irq_svc) from [<c00100fc>] (arch_cpu_idle+0x38/0x3c)
[ 2.585212] [<c00100fc>] (arch_cpu_idle) from [<c00579dc>] (cpu_startup_entry+0x1b0/0x26c)
[ 2.593452] [<c00579dc>] (cpu_startup_entry) from [<4000956c>] (0x4000956c)
[ 2.600390] CPU3: stopping
[ 2.603083] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 4.4.0-g58d0198-dirty #2
[ 2.610196] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[ 2.616286] [<c00160ec>] (unwind_backtrace) from [<c0012e08>] (show_stack+0x10/0x14)
[ 2.624008] [<c0012e08>] (show_stack) from [<c01f6bd8>] (dump_stack+0x80/0xc0)
[ 2.631209] [<c01f6bd8>] (dump_stack) from [<c0015348>] (handle_IPI+0x1ac/0x1c0)
[ 2.638586] [<c0015348>] (handle_IPI) from [<c00094d0>] (gic_handle_irq+0x90/0x94)
[ 2.646137] [<c00094d0>] (gic_handle_irq) from [<c00138d4>] (__irq_svc+0x54/0x90)
[ 2.653597] Exception stack(0xef0b3f88 to 0xef0b3fd0)
[ 2.658637] 3f80: 00000001 00000000 ef0b3fe0 c001b860 c0571388 00000000
[ 2.666797] 3fa0: 00000000 c08013c0 c08064b4 c07fe2e4 ef0b2000 c08064bc 00000001 ef0b3fd8
[ 2.674952] 3fc0: c00100f8 c00100fc 60000013 ffffffff
[ 2.679991] [<c00138d4>] (__irq_svc) from [<c00100fc>] (arch_cpu_idle+0x38/0x3c)
[ 2.687371] [<c00100fc>] (arch_cpu_idle) from [<c00579dc>] (cpu_startup_entry+0x1b0/0x26c)
[ 2.695614] [<c00579dc>] (cpu_startup_entry) from [<4000956c>] (0x4000956c)
[ 2.702553] CPU0: stopping
[ 2.705247] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.0-g58d0198-dirty #2
[ 2.712360] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[ 2.718449] [<c00160ec>] (unwind_backtrace) from [<c0012e08>] (show_stack+0x10/0x14)
[ 2.726171] [<c0012e08>] (show_stack) from [<c01f6bd8>] (dump_stack+0x80/0xc0)
[ 2.733373] [<c01f6bd8>] (dump_stack) from [<c0015348>] (handle_IPI+0x1ac/0x1c0)
[ 2.740750] [<c0015348>] (handle_IPI) from [<c00094d0>] (gic_handle_irq+0x90/0x94)
[ 2.748300] [<c00094d0>] (gic_handle_irq) from [<c00138d4>] (__irq_svc+0x54/0x90)
[ 2.755761] Exception stack(0xc0805f48 to 0xc0805f90)
[ 2.760800] 5f40: 00000001 00000000 c0805fa0 c001b860 c0571388 00000000
[ 2.768961] 5f60: 00000000 c08013c0 c08064b4 c07fe2e4 c0804000 c08064bc 00000001 c0805f98
[ 2.777116] 5f80: c00100f8 c00100fc 60000013 ffffffff
[ 2.782154] [<c00138d4>] (__irq_svc) from [<c00100fc>] (arch_cpu_idle+0x38/0x3c)
[ 2.789535] [<c00100fc>] (arch_cpu_idle) from [<c00579dc>] (cpu_startup_entry+0x1b0/0x26c)
[ 2.797781] [<c00579dc>] (cpu_startup_entry) from [<c0798c6c>] (start_kernel+0x3b0/0x3bc)
[ 2.805936] [<c0798c6c>] (start_kernel) from [<4000807c>] (0x4000807c)
[ 2.812448] ---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
但是出现了以上错误。
使用网络文件系统，查看SD卡识别的log
[ 2.540135] mmc0: new high speed SDHC card at address aaaa
[ 2.541197] mmcblk0: mmc0:aaaa SS08G 7.40 GiB
[ 2.543136] mmcblk0: p1 p2
看来是可能是文件系统挂载时，SD卡未识别到，导致错误出现，后边再看有没有解决方案。
查看硬件中断资源：cat /proc/interrupts
查看GPIO资源：cat /sys/kernel/debug/gpio