Subject: Re: [PATCH v3 1/1] ppc/crash: Reset spinlocks during crash

From: Michael Ellerman <[email-masked]>
Date: Tue, 12 May 2020 20:42:21 +1000

Paul Mackerras <[email-masked]> writes:
> On Wed, Apr 08, 2020 at 10:21:29PM +1000, Michael Ellerman wrote:
>> 
>> We should be able to just allocate the rtas_args on the stack, it's only
>> ~80 odd bytes. And then we can use rtas_call_unlocked() which doesn't
>> take the global lock.
>
> Do we instantiate a 64-bit RTAS these days, or is it still 32-bit?

No, yes.

> In the old days we had to make sure the RTAS argument buffer was
> below the 4GB point.

Yes you're right, that's still true.

I was thinking we were on the emergency stack, but we may not be.

> If that's still necessary then perhaps putting rtas_args inside the
> PACA would be the way to go.

Yeah I guess. Allocating a struct within the RMO for each CPU is not
that simple vs just putting it in the paca.

cheers