Re: [patch 2/8] Implement always-locked bit ops, for memory shared with an SMP hypervisor.

[Andi Kleen <ak@suse.de>]

On Thursday 03 August 2006 07:54, Christoph Lameter wrote:
> On Thu, 3 Aug 2006, Andi Kleen wrote:
> 
> > > I still wonder why you are so focused on ifdefs. Why would we need those?
> > 
> > Because the Xen drivers will run on a couple of architectures, including
> > IA64 and PPC.
> > 
> > If IA64 or PPC didn't implement at least wrappers for the sync ops
> > then they would all need special ifdefs to handle this.
> 
> No they would just need to do an #include <xen-bitops.h>

If IA64 and PPC64 wouldn't have xen-bitops.h (which you seem to argue 
for) then they would need ifdefs.

> > But you would still need to add that to IA64, PPC etc. too, so it 
> > would only avoid adding a single to the other architectures.
> 
> Could we not just add one fallback definition to asm-generic?

You mean into asm-generic/bitops.h? Then it would need ifdefs
to handle the i386/x86-64 case.

-Andi