Re: [PATCH 1/4] powerpc/powernv: handle the platform error reboot in ppc_md.restart

On Wed,  5 Jul 2017 14:04:19 +1000
Nicholas Piggin [off-list ref] wrote:

Unrecovered MCE and HMI errors are sent through a special restart
OPAL call to log the platform error. The downside is that they don't
go through normal crash paths, so they don't give much information
to the Linux console.

Change this by allowing them to set an error which then causes the
normal restart handler to use the platform error call. Have MCE and HMI
handlers set this and then use the normal panic path for unrecoverable
cases.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---

This patch is a bit clunky, setting this global variable. But it's
difficult to get this through the normal crash/panic paths by any
other way that I've found.

A concern is that we would like to add the opal log as early as
possible, but also print some information to the Linux console. This
goes against a competing concern that the more we do before logging
and xstop, the larger window something might go wrong.

So I would like to be able to cause opal to log a platform error
ASAP in the machine check handler, but then do some Linux crash
dumping before xstopping. That would require a new opal logging API
or convention though. So maybe this is an improvement (which also
allows patch 2 to be implemented more easily).

Anyway, discussion and criticism welcome.


Thanks,
Nick