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

[Russell Currey]

On Fri, 2015-11-27 at 16:40 +1100, Stewart Smith wrote:
> 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/
> 
It doesn't *depend* on it, it's just preferred.  It still works with older
Skiboot versions.  I will mention it in the actual commit message for the
next revision, though.

> (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)
> 
Yes, both this patch and the corresponding Skiboot patch should go to stable.