Re: [PATCH] x86/microcode: Add an option to reload microcode even if revision is unchanged

From: Raj, Ashok
Date: Thu Aug 29 2019 - 01:38:30 EST


Hi Boris,

sorry i added the wrong message id in the commit log.

https://lore.kernel.org/r/20190824085300.GB16813@xxxxxxx/

On Wed, Aug 28, 2019 at 10:33:22PM -0700, Ashok Raj wrote:
> During microcode development, its often required to test different versions
> of microcode. Intel microcode loader enforces loading only if the revision is
> greater than what is currently loaded on the cpu. Overriding this behavior
> allows us to reuse the same revision during development cycles.
> This facilty also allows us to share debug microcode with development
> partners for getting feedback before microcode release.
>
> Microcode developers should have other ways to check which
> of their internal version is actually loaded. For e.g. checking a
> temporary MSR for instance. In order to reload the same microcode do as
> shown below.
>
> # echo 2 > /sys/devices/system/cpu/microcode/reload
>
> as root.
>
>
> I tested this on top of the parallel ucode load patch
>
> https://lore.kernel.org/r/1566506627-16536-2-git-send-email-mihai.carabas@xxxxxxxxxx/

Please update with the following:

https://lore.kernel.org/r/20190824085300.GB16813@xxxxxxx/

Cheers,
Ashok