Re: [PATCH 0/2] x86/microcode: support for microcode update in Xen dom0

H. Peter Anvin
2011-02-02T21:48:07Z

On 02/02/2011 12:57 PM, Borislav Petkov wrote:
> On Wed, Feb 02, 2011 at 11:52:22AM -0800, H. Peter Anvin wrote:
>> 3. Arguably on native hardware we should still load the microcode into
>> RAM in the boot loader, and install it on the very early CPU bringup
>> path. That means locking down some (currently) 400K of RAM to handle
>> different combinations of CPUs, or the additional complexity of
>> jettisoning microcode which cannot be used while still be able to deal
>> with hotplug. I think there is a strong case for this model, which
>> would mean moving the microcode into /boot anyway.
>
> /me like it, sounds very nifty. So how do we want to do that, we add
> a field to the real-mode kernel header that tells us where to find
> the microcode image and we take it and apply the ucode somewhere in
> do_boot_cpu() path?
>

We already have a mechanism for passing arbitrary blobs -- the linked
list -- so we don't have to add a new field at all.

-hpa