• Steven Rostedt's avatar
    ftrace: dump out ftrace buffers to console on panic · 3f5a54e3
    Steven Rostedt authored
    
    
    At OLS I had a lot of interest to be able to have the ftrace buffers
    dumped on panic.  Usually one would expect to uses kexec and examine
    the buffers after a new kernel is loaded. But sometimes the resources
    do not permit kdump and kexec, so having an option to still see the
    sequence of events up to the crash is very advantageous.
    
    This patch adds the option to have the ftrace buffers dumped to the
    console in the latency_trace format on a panic. When the option is set,
    the default entries per CPU buffer are lowered to 16384, since the writing
    to the serial (if that is the console) may take an awful long time
    otherwise.
    
    [
     Changes since -v1:
      Got alpine to send correctly (as well as spell check working).
      Removed config option.
      Moved the static variables into ftrace_dump itself.
      Gave printk a log level.
    ]
    Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    3f5a54e3