[v2, 1/3] powerpc/powernv: handle the platform error reboot in ppc_md.restart

[Michael Ellerman]

On Wed, 2017-07-19 at 06:59:10 UTC, Nicholas Piggin 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 Linux crash paths, so they don't give much information
> to the Linux console.
> 
> Change this by providing a special crash function which does some of
> the console flushing from the panic() path before calling firmware to
> reboot.
> 
> The downside of this is a little more code to execute before reaching
> the firmware reboot. However in practice, it's critical to get the
> Linux console messages output in order to debug a problem. So this is
> a desirable tradeoff.
> 
> Note on the implementation: It is difficult to plumb a custom reboot
> handler into the panic path, because panic does a little bit too much
> work. For example, it will try to delay with the timebase, but that
> may be corrupted in some cases resulting in a hang without reaching
> the platform reboot. Another problem is that panic can invoke the
> crash dump code which is not what we want in the case of a hardware
> platform error. Long-term the best solution will be to rework the
> panic path so it can be suitable for this kind of panic, but for now
> we just duplicate a bit of the code.
> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> Reviewed-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/b746e3e01e70d23ef53dcde1203ab7

cheers