linux-kernel - Re: [PATCH 2/2] x86, microcode: Make reload interface per system

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Message-ID: <4FE4B796.3050009@zytor.com>
Date:	Fri, 22 Jun 2012 11:21:10 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Nix <nix@...eri.org.uk>
CC:	Borislav Petkov <bp@...64.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Henrique de Moraes Holschuh <hmh@....eng.br>,
	"Yu\, Fenghua" <fenghua.yu@...el.com>, X86-ML <x86@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Andreas Herrmann <andreas.herrmann3@....com>
Subject: Re: [PATCH 2/2] x86, microcode: Make reload interface per system

On 06/22/2012 09:26 AM, Nix wrote:
> On 20 Jun 2012, Borislav Petkov uttered the following:
>> I know, right. Whose idea was it to do it like that I don't know.
>> AFAICT, Intel delivers ucode as a single blob too, so why split it? The
>> driver picks out the right blob anyway.
> 
> Only if supplied over the old interface. Over the new interface,
> we just see
> 
>     microcode: error! Bad data in microcode data file
> 
> in the log. So clearly the driver doesn't know how to split up the
> microcode.bin that Intel provides, and (until Henrique's iucode-tool or
> something like it becomes ubiquitous) the old interface, and
> microcode_ctl, cannot be removed.
> 

Even more importantly, to do early microcode updates we need to stash
away not just the current CPU's microcode but any compatible CPU's
microcode, so just loading a single one is not going to work...

Oif.

	-hpa

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