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From: Stewart Smith <stewart@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
	Russell Currey <ruscur@russell.cc>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [V3] powerpc/powernv: Add a kmsg_dumper that flushes console output on panic
Date: Fri, 15 Jan 2016 15:59:56 +1100	[thread overview]
Message-ID: <87a8o78mk3.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <1452600325.20985.4.camel@ellerman.id.au>

Michael Ellerman <mpe@ellerman.id.au> writes:
>> > > Applied to powerpc next, thanks.
>> > > 
>> > > https://git.kernel.org/powerpc/c/affddff69c55eb68969448f35f
>> > 
>> > The firmware interface changed slightly since this kernel patch[1], it
>> > added a parameter to OPAL_CONSOLE_FLUSH which accepted the terminal
>> > number to flush, theoretically allowing this to be plumbed into TTY
>> > layer or something too.
>> > 
>> > So, we'll either have to update this patch or replace it with an updated
>> > one.
>> > 
>> > [1] i'm pushing the accepted skiboot patch now.
>> > 
>> I'm working on an updated kernel patch to use the new parameter and additional
>> return values, so I suppose it's up to mpe whether or not this patch gets
>> merged now and another gets sent later to amend it, or if this patch gets
>> reverted in next and I can send a V4 adding the new stuff.
>
> Doh. I'd rather not revert it, unless we have to.
>
> Basically we're passing junk in r3, which skiboot is expecting to be the
> terminal number.

and skiboot will just return OPAL_PARAMETER and the kernel code ignores
the return value, so all will be *fine*. It may even work by accident sometimes.

> So running the current kernel code on the updated skiboot shouldn't crash and
> burn, it just won't actually work the way it's supposed to.

Right, it'll just do nothing.

> So my preference would be just an incremental patch ASAP to fix the kernel to
> do the right thing with the new interface.

I see that's merged now, which is great! Even if someone is bisecting
back, things will be fine too.

-- 
Stewart Smith
OPAL Architect, IBM.

  reply	other threads:[~2016-01-15  5:07 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-27  6:23 [PATCH V3] powerpc/powernv: Add a kmsg_dumper that flushes console output on panic Russell Currey
2016-01-11  9:14 ` [V3] " Michael Ellerman
2016-01-12  3:44   ` Stewart Smith
2016-01-12  4:17     ` Russell Currey
2016-01-12 12:05       ` Michael Ellerman
2016-01-15  4:59         ` Stewart Smith [this message]
2016-01-15 10:07           ` Michael Ellerman

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