[Qemu-devel] Re: [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Anthony Liguori]

On 04/02/2010 10:01 AM, Paolo Bonzini wrote:
> On 04/01/2010 10:27 PM, Blue Swirl wrote:
> > It will not be safe to use kvm_enabled() in vl.c, so there needs to be
> > a target dependent helper. The call to kvm_init could remain in vl.c,
> > likewise it's not strictly needed to move kvm_allowed to arch_init.c.
>
> Not really, because kvm_allowed _can_ be used from once-compiled 
> files.  The attached patch makes kvm-all.c be compiled always, even if 
> !CONFIG_KVM; functions that require kvm are almost always omitted for 
> now (so checking kvm_enabled() is required to call them).  However, 
> kvm_init is stubbed so that vl.c can call it.
>
> In the future we could add more stubbing and ultimately do this 
> unconditionally:
>
>    #define kvm_enabled() kvm_allowed
>
> With this patch vl.c can already be compiled once, but I did not 
> include it because it would conflict with my balloon.c series; I'm 
> doing enough rebasing these days.  Also, qemu-kvm is a bit behind qemu 
> and all these patches are nightmares for the merges, so it's better 
> IMO if things are left to calm down a bit.

Having kvm-all.c compile with and without CONFIG_KVM is pretty ugly IMHO.

Is compiling vl.c once really that important of a goal?  Wouldn't it be 
better to split bits out of vl.c and have those compile once?  Ideally, 
vl.c should be so small that compiling per-target shouldn't matter.

Regards,

Anthony Liguori

> > They just caused problems with the poisoning check in patch 2/2.
>
> Poisoning kvm_enabled is right, but poisoning kvm_allowed is overkill.
>
> Paolo