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

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.


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

Sweet, thanks.


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