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

[Boris Ostrovsky <boris.ostrovsky@xxxxxxx>]

On 11/26/2012 09:13 AM, Ian Campbell wrote:
> 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.
I submitted a fix for fam 16h to Linux right before the Thanksgiving 
break in US and was planning to look at Xen as well. Give me a day or 
two to test it.
-boris

> > The hypervisor is really going to take care of all other aspects
> > here.
> Sweet, thanks.
>
> Ian.

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