Re: [PATCH 2/4] Revert "x86/boot: Fail the boot if !M486 and CPUID is missing"

[Andy Lutomirski]

On Thu, Dec 1, 2016 at 1:02 AM, Borislav Petkov <bp@xxxxxxxxx> wrote:
> On Thu, Dec 01, 2016 at 06:53:50AM +0100, Peter Zijlstra wrote:
>> On Wed, Nov 30, 2016 at 12:34:53PM -0800, Andy Lutomirski wrote:
>> > This reverts commit ed68d7e9b9cfb64f3045ffbcb108df03c09a0f98.
>> >
>> > The patch wasn't quite correct -- there are non-Intel (and hence
>> > non-486) CPUs that we support that don't have CPUID.  Since we no
>> > longer require CPUID for sync_core(), just revert the patch.
>>
>> Might be useful to enumerate which special parts these are.
>
> Right, and since we test for CPUID support at early boot, I think we
> should use the X86_FEATURE_CPUID aspect from what I proposed earlier:
>
> https://lkml.kernel.org/r/20161120111917.pw3alolx4fksfwbv@xxxxxxx

Maybe we should just make the kernel work fully without CPUID.  There
isn't much to do on top of your patch -- I think we mainly want to
make the cpuid driver refuse to load.

--Andy