linux-kernel - Re: Intel Microcode loader, tg3 driver, and the -rc8-mmotd New World Order firmware...

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Message-Id: <1215100465.10393.585.camel@pmac.infradead.org>
Date:	Thu, 03 Jul 2008 16:54:25 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	"Giacomo A. Catenazzi" <cate@...ian.org>,
	Tigran Aivazian <tigran@...azian.fsnet.co.uk>,
	Valdis.Kletnieks@...edu, Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	"Selbak, Rolla N" <rolla.n.selbak@...el.com>,
	Shaohua Li <shaohua.li@...el.com>
Subject: Re: Intel Microcode loader, tg3 driver, and the -rc8-mmotd New
	World Order firmware...

On Thu, 2008-07-03 at 06:56 -0700, Arjan van de Ven wrote:
> On Thu, 03 Jul 2008 11:24:34 +0200
> "Giacomo A. Catenazzi" <cate@...ian.org> wrote:
> 
> > There are two format of Intel CPU microcode and two methods to load
> > it.
> > - old: the microcodes are in a big file, which include multiple
> >    microcodes (for multiple CPU).  The driver require a char device
> >    and a user space loader ("microcode_ctl")
> > - new: one microcode per file, using the 'request_firmware'
> >    infrastructure. No user space support needed.

Actually there are three:

1. The text format 'microcode.dat', including updates for all CPUs.
2. The binary format output by microcode_ctl, still including all CPUs.
3. The smaller files with just the relevant subset of #2.

The kernel (since 2006) can actually take either #2 or #3. The udev
scripts I just posted will use microcode_ctl to feed it #2, when they
find #1 on the file system.

A small amount of extra work in the userspace tool would let those udev
scripts feed #3 to the kernel, and then the code in the kernel to select
the appropriate update could be removed.

> > Actually Intel provides only the old methods.
> > There was talks with Arjan and Intel about the distribution format
> > for the new methods. But I don't have any new.
> > I think that when the new format is fully specified (directory
> > structure, tar, gzip,...) Intel will distribute the microcodes
> > in the new form.

Doesn't the "new format" (#3) involve hard links too, since there are
some cases where the same microcode update applies to more than one CPU
revision?

> we hope to switch to the new form but there's the small case of
> "installed base" using ancient kernels, and it's kind of not nice to
> have to release 2 sets. At some point we will switch over though.

Do we really need to _ship_ it in a different form? It's not exactly
hard to convert from the text form (#1) to either of the other two --
either on the fly in udev scripts, or at installation time.

-- 
dwmw2

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