Re: [Disscussion] Moving x86 code out of kvm.h

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Jerone Young wrote:
> This is a continuation of a conversation I have been having with Izik
> Eidus on IRC today.
>
> I plan on moving x86 code out of kvm.h and into kvm-x86.h. kvm-x86.h
> would then include kvm.h and would be included by files like svm.c
> instead of kvm.h. 
>
>   

Which kvm.h are we talking about? include/linux/kvm.h or drivers/kvm/kvm.h?

> Izik pointed out a big issue with this approach and that is it breaks
> compatibility with older userspace. We believe that everyone still cares
> that older userspace should be able to compile against a newer kvm
> kernels. Is this true or should we just dump it?
>   

Of course we can't break compatibility without an excellent reason.

> Assuming this is true, we have come up with an interesting solution to
> the problem.
>
> - creation of new header name "portablekvm.h" (please give a better name
> if you know one). This would be the new place for common code that would
> normally be kvm.h.
>
> - still create header "kvm-x86.h" for x86 code and would include this
> new "portablekvm.h" header.
>
> - keep compatibility with older userspace by taking header "kvm.h" and
> jsut have it include kvm-x86.h &  portablekvm.h and have no other code
> (unless it's for compatibility).
>
> What does everyone thing about this ?
>
>   

Have kvm.h include <asm/kvm.h>

> Also a side discussion is should we really start thinking about having a
> userspace header and stop userspace apps from including kernel headers.
> This does lead to a problem where if the kernel header is updated the
> userspace header must also be updated (but maybe it's time to bite the
> bullet)?
>
>   

The userspace header is include/linux/kvm.h.  No need to be cruel to
innocent bullets.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


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