Re: [Xen-devel] [RFC PATCH] Scan initramfs for microcode cpio archive. (v1)

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Mon, Jul 15, 2013 at 08:18:51AM +0100, Jan Beulich wrote:
> >>> On 12.07.13 at 16:25, Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx> wrote:
> > Greetings,
> > 
> > Please see the following patch which implements a mechanism to scan
> > the initramfs for the format of an microcode files. This is a feature
> > that the Linux kernel has since v3.10 - where it searches in the
> > initramfs for an archive of the microcode blob. The format is documented
> > in the Linux tree and the commit description contains it.
> > 
> > The tool to make this work is the initramfs creator. The author has
> > provided an RFC patch: 
> > http://article.gmane.org/gmane.linux.kernel.initramfs/3318 
> > which does that.
> 
> Looking at that script change I'm getting the impression that the
> representation is as uncompressed cpio containing the ucode
> blobs followed by compressed cpio containing all the "normal"
> stuff. Which iiuc means that an unaware kernel can't deal with
> such an image (as the consumer needs to know that it has to
> skip the initial portion). Unless that understanding of mine is
> wrong - isn't that a rather bad design?
> 

The kernel if compiled without EARLY_INITRAMFS.. and an initramfs
_with_ the uncompressed cpio containing the ucode blob followed
by compressed cpio containing the normal stuff boots. I tested this
with a v3.9 and v3.11 kernel and both booted without trouble.

> Jan
> 
> 

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