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

[Jerone Young <jyoung5-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>]

On Thu, 2007-11-15 at 10:34 +0200, Avi Kivity wrote:
> 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?

Whoops should have been more clear about this. It was late for me :-)

But I was first referring to inclue/linux/kvm.h.

I believe I actually started looking at drivers/kvm/kvm.h at the same
time (which is why my email is so screwed, but this is not as big of a
deal for now). 

Never the less it looks like the discussion has taken off. I'll just
join in that.


> 
> > 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.
> 


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