Messages in this thread | | | Date | Wed, 2 Aug 2006 22:54:17 -0700 (PDT) | From | Christoph Lameter <> | Subject | Re: [patch 2/8] Implement always-locked bit ops, for memory shared with an SMP hypervisor. |
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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>
> > Maybe the best thing would be to have proper atomic ops in UP mode on > > i386? The current way of just dropping the lock bit is the source of the > > troubles. > > It's a huge performance difference.
I understand but why dont we use regular ops explicitly instead of hacking the atomic ops. Then we would not have unhack them now.
> > Just adding a single line #include <asm/xen-bitops.h> to drivers that need > > this functionality is not an undue burden for the drivers that support > > Xen. They have to use special _xxx bitops anyways. > > Ok it could be put into a separate file (although with a neutral name) > > 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?
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