Re: [PATCH] fixup 3dnow! support

Avi Kivity
2008-05-07T08:19:26Z

Alexander Graf wrote:
>
> On May 6, 2008, at 6:27 PM, Glauber Costa wrote:
>
>> qemu recently added support for 3dnow instructions. Because of
>> that, 3dnow will be featured among cpuid bits. But this will
>> break kvm in cpus that don't have those instructions (which includes
>> my laptop). So we fixup our cpuid before exposing it to the guest.
>
> I actually don't see where the problem is here. As far as I read the
> code, the CPUID feature function gets received from the host CPU and
> bitwise ANDed with a bunch of features that are known to work. What's
> wrong with that approach?

Nothing. Note that "known to work" needs to be queried from the kernel,
since userspace and the kernel are not guaranteed to match.

> But I'm pretty sure Dao can tell us a lot more about this. Has there
> been any progress in getting the new CPUID code in? I think I could
> review this sometime soon.

Who's Dao? Do you mean Dan?

--
error compiling committee.c: too many arguments to function