Re: [GIT PULL -tip v3] fix 39 'make headers_check' warnings

Avi Kivity
2009-01-19T11:54:25Z

Sam Ravnborg wrote:
>> They are. This bits advertise to userspace what features kvm supports,
>> both compile- and run-time.
>>
>
> This is wrong...
> The headers does not change with the kernel configuration and advertising the
> kvm features via a .h file like this is simply plain broken.
>

Ok. Don't know why I thought unifdef was supplied with the full
configuration.

> You cannot assume that the header files are generated with the exact same config
> as used by the running kernel.
>

This is just for arch specific defines. I'll move these to asm/kvm.h.

> And userspace has in no way access to the CONFIG_ namespace which is purely kernel-internal.
>
> I cannot see how you have ever seen kcm advertise that for example KVM_CAP_USER_NMI
> equals to 22 because CONFIG_X86 is never (supposed to be) defined in userspace -
> except if you did so yourself by some means.
>

We did, we ship a hacked-up kvm.h (generated by unifdef) with our userspace.

Thanks for the clarifications, helpful as always.

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