linux-kernel - Re: [patch 0/4] x86: AMD microcode patch loading v2 fixes

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Date:	Wed, 30 Jul 2008 11:57:18 +0200
From:	"Dmitry Adamushko" <dmitry.adamushko@...il.com>
To:	"Peter Oruba" <peter.oruba@....com>
Cc:	"Max Krasnyansky" <maxk@...lcomm.com>,
	"Ingo Molnar" <mingo@...e.hu>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"Tigran Aivazian" <tigran@...azian.fsnet.co.uk>,
	"H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [patch 0/4] x86: AMD microcode patch loading v2 fixes

2008/7/30 Peter Oruba <peter.oruba@....com>:
>> [ ... ]
>
> Since ucode updates may fix severe issues, it is supposed to happen as early
> as possible. If you re-plug your CPU into your socket, your BIOS also
> applies a ucode patch, but that won't necessarily be the latest and critical
> one.

Hum, let's say we don't do it from cpu-hotplug handlers [1] but from
start_secondary() before calling cpu_idle()? [*]

This way, we do it before any other task may have a chance to run on a
cpu which is not a case with cpu-hotplug handlers
(and we don't mess-up with cpu-hotplug events :-)

[ the drawback is that 'microcode' subsystem is not local to
microcode.c anymore ]

[1] if we need a sync. operation in cpu-hotplug handlers and IPI is
not ok (say, we need to run in a sleepablel context) then perhaps it's
workqueues + wait_on_cpu_work(). But then it's not a bit later than
could have been with [*].

heh, this issue has already popped up in another thread so it should
be fixed asap, imho.

Ingo, Peter? What would be the best way from your pov?


>
> Peter
>

-- 
Best regards,
Dmitry Adamushko
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