Russell Currey [off-list ref] writes:

On Fri, 2015-11-27 at 16:40 +1100, Stewart Smith wrote:

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Russell Currey [off-list ref] writes:

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On BMC machines, console output is controlled by the OPAL firmware and=

 is

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only flushed when its pollers are called.=C2=A0=C2=A0When the kernel i=

s in a panic

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state, it no longer calls these pollers and thus console output does n=

ot

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completely flush, causing some output from the panic to be lost.
=20
This patch adds a new kmsg_dumper which gets called at panic time to e=

nsure

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panic output is not lost.=C2=A0=C2=A0It 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.

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You may want to add to commit message that this depends on:
https://patchwork.ozlabs.org/patch/547379/
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It doesn't *depend* on it, it's just preferred. =C2=A0It still works with=

 older

Skiboot versions. =C2=A0I will mention it in the actual commit message fo=

r the

next revision, though.

More meaning that it depends on that patch being merged before, say the
PCI hotplug patches, which add a *different* OPAL call at the same ID -
and that it depends on *this* patch with *this* API rather than a
modified one being merged.

Otherwise, if, say, I merged some other new OPAL call into skiboot
first, this patch would likely cause all sorts of trouble.

It's also a handy hint to Michael to ensure the skiboot side of things
is merged and okay before merging kernel things in.