[RK3399][Android7.1] 调试笔记 --- 查看开机上一次kernel log

Platform: RK3399
OS: Android 7.1
Kernel: v4.4.83

rk3288平台，rk自己实现了一套机制获取上一次的kernel log.
rk3399平台，使用了内核框架中的ramoops机制。

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查看方法：

#cat /sys/fs/pstore/console-ramoops-0

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要开启此功能，需要做以下几点配置(rk3399默认都开启了)

打开功能：
rockchip_defconfig:

CONFIG_PSTORE=y
CONFIG_PSTORE_CONSOLE=y
CONFIG_PSTORE_PMSG=y
CONFIG_PSTORE_RAM=y

驱动对应路径：
kernel/fs/pstore

配置内存地址以及各个功能size
rk3399-android.dtsi:

ramoops_mem: ramoops_mem {
    reg = <0x0 0x110000 0x0 0xf0000>;
    reg-names = "ramoops_mem";
};

ramoops {
    compatible = "ramoops";
    record-size = <0x0 0x20000>;
    console-size = <0x0 0x80000>;
    ftrace-size = <0x0 0x00000>;
    pmsg-size = <0x0 0x50000>;
    memory-region = <&ramoops_mem>;
};

各个property意义：

- compatible: must be "ramoops"
- memory-region: phandle to a region of memory that is preserved between reboots
Optional properties:
- ecc-size: enables ECC support and specifies ECC buffer size in bytes (defaults to no ECC)
- record-size: maximum size in bytes of each dump done on oops/panic (defaults to 0)
- console-size: size in bytes of log buffer reserved for kernel messages (defaults to 0)
- ftrace-size: size in bytes of log buffer reserved for function tracing and profiling (defaults to 0)
- pmsg-size: size in bytes of log buffer reserved for userspace messages (defaults to 0)
- unbuffered: if present, use unbuffered mappings to map the reserved region (defaults to buffered mappings)
- no-dump-oops: if present, only dump panics (defaults to panics and oops) 

开机后做mount:
system/core/rootdir/init.rc:

# pstore/ramoops previous console log
mount pstore pstore /sys/fs/pstore
chown system log /sys/fs/pstore/console-ramoops
chmod 0440 /sys/fs/pstore/console-ramoops
chown system log /sys/fs/pstore/pmsg-ramoops-0
chmod 0440 /sys/fs/pstore/pmsg-ramoops-0

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参考：

ramoops&pstore简要说明