On Sun, Dec 02, 2007 at 10:34:28PM +0000, David Laight wrote:
> sys/arch/amd64/include/frameasm.h defines macros for STI and CLI
> for XEN that use 2 temp registers.
> I think the patch below is equivalent - but only uses 1.
> 
> --- frameasm.h  22 Nov 2007 16:16:45 -0000      1.8
> +++ frameasm.h  2 Dec 2007 22:00:04 -0000
> @@ -140,15 +140,13 @@
>  #define CLI(reg1,reg2) \
>         movl CPUVAR(CPUID),%e/**/reg1 ;                 \
>         shlq $6,%r/**/reg1 ;                                    \
> -       movq _C_LABEL(HYPERVISOR_shared_info),%r/**/reg2 ;      \
> -       addq %r/**/reg1,%r/**/reg2 ;                            \
> -       movb $1,EVTCHN_UPCALL_MASK(%r/**/reg2)
> +       addq _C_LABEL(HYPERVISOR_shared_info),%r/**/reg1 ;      \
> +       movb $1,EVTCHN_UPCALL_MASK(%r/**/reg1)
>  #define STI(reg1,reg2) \
>         movl CPUVAR(CPUID),%e/**/reg1 ;                 \
>         shlq $6,%r/**/reg1 ;                                    \
> -       movq _C_LABEL(HYPERVISOR_shared_info),%r/**/reg2 ;      \
> -       addq %r/**/reg1,%r/**/reg2 ;                            \
> -       movb $0,EVTCHN_UPCALL_MASK(%r/**/reg2)
> +       addq _C_LABEL(HYPERVISOR_shared_info),%r/**/reg1 ;      \
> +       movb $0,EVTCHN_UPCALL_MASK(%r/**/reg1)
>  #else /* XEN */
>  #define CLI(reg1,reg2) cli
>  #define STI(reg1,reg2) sti
> 
> However I don't have a XEN install so can't test it.

It works. But please keep the 2 registers as macro arguments, even if only
one is used for now: I may need a STIC() in the future, and this one would
need 2 arguments.

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la difference
--