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    SubjectRe: Query about kdump_msg hook into crash_kexec()
    Date
    > AFAIK, kexec is used sneak rebooting way when the system face unexpected
    > scenario on some devices. (Some embedded is running very long time, then
    > it can't avoid memory bit corruption. all of reset is a last resort.
    > and a vendor gather logs at periodically checkback).
    >
    > The main purpose of to introduce KMSG_DUMP_KEXEC is to be separate it
    > from KMSG_DUMP_PANIC. At kmsg_dump() initial patch, KMSG_DUMP_PANIC
    > is always called both kdump is configured or not. But it's no good idea
    > the same log is to be appeared when both kexec was successed and failured.
    > Moreover someone don't want any log at kexec phase. They only want logs
    > when real panic (ie kexec failure) route. Then, I've separated it to two.
    > Two separated argument can solve above both requreiment.

    A bit additional explanation, An original patch have kmsg_dump(KMSG_DUMP_PANIC)
    callsite at following point. I didn't think it makes either embedded or
    kdump folks happiness. Thus I moved it after crash_kexec().


    ---------------------------------------------------------------------
    @@ -74,6 +75,7 @@ NORET_TYPE void panic(const char * fmt, ...)
    dump_stack();
    #endif

    + kmsg_dump(KMSG_DUMP_PANIC);
    /*
    * If we have crashed and we have a crash kernel loaded let it handle
    * everything else.
    * Do we want to call this before we try to display a message?
    */
    crash_kexec(NULL);
    ---------------------------------------------------------------------




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