[PATCH V2] powerpc/powernv: Add a kmsg_dumper that flushes console output on panic

[Stewart Smith]

Russell Currey <ruscur at russell.cc> writes:
> On BMC machines, console output is controlled by the OPAL firmware and is
> only flushed when its pollers are called.  When the kernel is in a panic
> state, it no longer calls these pollers and thus console output does not
> completely flush, causing some output from the panic to be lost.
>
> This patch adds a new kmsg_dumper which gets called at panic time to ensure
> panic output is not lost.  It accomplishes this by calling OPAL_CONSOLE_FLUSH
> in the OPAL API, and if that is not available, the pollers are called enough
> times to (hopefully) completely flush the buffer.

You may want to add to commit message that this depends on:
https://patchwork.ozlabs.org/patch/547379/

(which I'm about to go review)

Considering this does address an actual bug, should this go to stable@ ?

(Same question for the skiboot patch)