Re: [Xen-devel] pvops microcode support for AMD FAM >= 15

[Ian Campbell <ijc@xxxxxxxxxxxxxx>]

On Mon, 2012-11-26 at 13:44 +0000, Jan Beulich wrote:
> >>> On 26.11.12 at 14:21, Ian Campbell <ijc@xxxxxxxxxxxxxx> wrote:
> > Debian has decided to take Jeremy's microcode patch [0] as an interim
> > measure for their next release. (TL;DR -- Debian is shipping pvops Linux
> > 3.2 and Xen 4.1 in the next release. See http://bugs.debian.org/693053 
> > and https://lists.debian.org/debian-devel/2012/11/msg00141.html for some
> > more background).
> > 
> > However the patch is a bit old and predates the use introduction of
> > separate firmware files for AMD family >= 15h. Looking at the SuSE
> > forward ported classic Xen patches it seems like the following patch is
> > all that is required. But it seems a little too simple to be true and I
> > don't have any such processors to test on.
> > 
> > Jan, can you recall if it really is that easy on the kernel side ;-)
> 
> While so far I didn't myself run anything on post-Fam10 systems
> either, it really ought to be that easy - the patch format didn't
> change, it's just that they decided to spit the files by family to
> keep them manageable.
> 
> The only other thing to check for is that you don't have any
> artificial size restriction left in that code (I think patch files early
> on were limited to 4k in size, and that got lifted during the last
> couple of years).

I can't find one by inspection, it uses the standard request_firmware
interface and stashes the result in a valloc'd buffer, neither of which
suffer from any 4K related limitations AFAIK.

I'll try and track something more recent down to test but the worst
downside of applying this patch seems to be that something which doesn't
work still doesn't work.

> The hypervisor is really going to take care of all other aspects
> here.

Sweet, thanks.

Ian.

-- 
Ian Campbell
Current Noise: Testament - The Ritual

Chemist who falls in acid will be tripping for weeks.


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