Re: [PATCH] microcode: Scan the multiboot payloads for cpio format microcode blob. (v3).

[Jeremy Fitzhardinge <jeremy@goop.org>]

On 09/25/2013 05:57 AM, Konrad Rzeszutek Wilk wrote:
> The way to use this is by the 'ucode' parameter. It has now two meanings:
>   [<index>|initrd]
>
> Which CANNOT be used together. By default this auto scanning is turned off
> as Jan pointed out that: "Xen otoh has to be careful not to
> mis-interpret a blob passed to a non-Linux Dom0 as a CPIO. How
> good the guarding against this is in the code I'll have to check".
> [...]
> There is also the question whether the parameter should be 'cpio','initrd'
> or 'scan'. As in the future the extraction of the payload could be from
> a different format than the cpio (say a microcode blob with an magic
> string at the start). The author believes that at that time the logic
> to scan the mulitboot payloads can be expanded to also scan formats other
> than cpio format.

Why treat a microcode.bin and cpio differently? Aren't they both just
file formats that can be parsed to (possibly) extract microcode update
info? That being so, why change the ucode parameter? Wouldn't you just
set it to ucode=N, where N is the module index either a microcode.bin or
cpio or anything else multiboot module?

    J


>
> These patches are also available at:
>
>   git://xenbits.xen.org/people/konradwilk/xen.git microcode.v3
>
>  docs/misc/xen-command-line.markdown |  14 ++-
>  xen/arch/x86/microcode.c            | 177 ++++++++++++++++++++++++++++++++----
>  xen/common/Makefile                 |   2 +-
>  xen/common/earlycpio.c              | 151 ++++++++++++++++++++++++++++++
>  xen/include/xen/earlycpio.h         |  14 +++
>  5 files changed, 337 insertions(+), 21 deletions(-)
>
> Konrad Rzeszutek Wilk (2):
>       microcode: Scan the initramfs payload for microcode blob.
>       microcode: Check whether the microcode is correct.
>
>
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