On 05/31/2011 09:53 AM, Christoph Lameter wrote:
> Index: linux-2.6/arch/x86/Kconfig.cpu
> ===================================================================
> --- linux-2.6.orig/arch/x86/Kconfig.cpu 2011-05-31 11:28:24.202948792 -0500
> +++ linux-2.6/arch/x86/Kconfig.cpu 2011-05-31 11:29:36.742948327 -0500
> @@ -312,6 +312,16 @@ config X86_CMPXCHG
> config CMPXCHG_LOCAL
> def_bool X86_64 || (X86_32 && !M386)
>
> +#
> +# CMPXCHG_DOUBLE needs to be set to enable the kernel to use cmpxchg16/8b
> +# for cmpxchg_double if it find processor flags that indicate that the
> +# capabilities are available. CMPXCHG_DOUBLE only compiles in
> +# detection support. It needs to be set if there is a chance that processor
> +# supports these instructions.
> +#
> +config CMPXCHG_DOUBLE
> + def_bool GENERIC_CPU || X86_GENERIC || !M386
> +
> config X86_L1_CACHE_SHIFT
> int
> default "7" if MPENTIUM4 || MPSC
Per previous discussion:
- Drop this Kconfig option (it is irrelevant.) CONFIG_CMPXCHG_LOCAL is
different: it indicates that CMPXCHG is *guaranteed* to exist.
> + asm volatile(LOCK_PREFIX_HERE "cmpxchg8b (%%esi); setz %1"\
> + : "d="(__dummy), "=a" (__ret) \
> + : "S" ((ptr)), "a" (__old1), "d"(__old2), \
> + "b" (__new1), "c" (__new2) \
> + : "memory"); \
> + __ret; })
> + asm volatile("cmpxchg8b (%%esi); tsetz %1" \
> + : "d="(__dummy), "=a"(__ret) \
> + : "S" ((ptr)), "a" (__old), "d"(__old2), \
> + "b" (__new1), "c" (__new2), \
> + : "memory"); \
> + __ret; })
d= is broken (won't even compile), and there is a typo in the opcode
(setz, not tsetz).
Use LOCK_PREFIX and +m here too.
-hpa
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