On Mon, 2012-03-12 at 22:53 -0700, David Miller wrote:

From: Avery Pennarun <redacted>
Date: Tue, 13 Mar 2012 01:36:36 -0400

quoted

The last patch in this series implements a new CONFIG_PRINTK_PERSIST option
that, when enabled, puts the printk buffer in a well-defined memory location
so that we can keep appending to it after a reboot.  The upshot is that,
even after a kernel panic or non-panic hard lockup, on the next boot
userspace will be able to grab the kernel messages leading up to it.  It
could then upload the messages to a server (for example) to keep crash
statistics.

On some platforms there are formal ways to reserve areas of memory
such that the bootup firmware will know to not touch it on soft resets
no matter what.  For example, on Sparc there are OpenFirmware calls to
set aside such an area of soft-reset preserved memory.

I think some formal agreement with the system firmware is a lot better
when available, and should be explicitly accomodated in these changes
so that those of us with such facilities can very easily hook it up.

Shouldn't this all be near the pstore effort? I know pstore and the
soft-reset stuff aren't quite the same, but if that's the best Sparc can
do, then why not?

OTOH if Sparc can actually do pstore too, then it might make sense.

What I guess I'm saying is that we should try and minimize the duplicate
efforts here.. and it seems to me that writing a soft reset x86 backend
to pstore for those machines that don't actually have the acpi flash
crap might be more useful and less duplicative.

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