linux-kernel - Re: [PATCH] perf/x86: fix microcode revision check for SNB-PEBS

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Date:	Fri, 24 Aug 2012 18:26:46 +0200
From:	Borislav Petkov <bp@...64.org>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...e.hu,
	andi@...stfloor.org
Subject: Re: [PATCH] perf/x86: fix microcode revision check for SNB-PEBS

On Fri, Aug 24, 2012 at 06:14:51PM +0200, Stephane Eranian wrote:
> So you're saying there is a cmdline tool that can use another
> interface to pass the ucode to the kernel. I am using the
> microcode_ctl on Ubuntu 11.04. Apparently that one is still using the
> old interface. But I may not be the only one in this situation then,
> so I think it's worth fixing now.
>
> What's the tool to update the ucode using the "new" interface then?

Well,

last time we talked about it:
http://marc.info/?l=linux-kernel&m=134012203712243 I was advocating the
following way:

Put ucode image into /lib/firmware/amd-ucode or /lib/firmware/intel-ucode and then do

$ echo 1 > /sys/devices/system/cpu/microcode/reload

which I think is the easiest but hpa had some reservations about it and
wanted to keep the old method too.

But looking at the code, this *actually* should work on Intel now too.

So, I'd say you can use both on Intel, it depends on them whatever they
decide to do in the future.

On AMD we have only the "echo 1" thing.

Alternatively, "rmmod microcode; modprobe microcode" works too but some
people wouldn't want to reload modules in order to update ucode.

-- 
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
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