[PATCH] ARM: 2664/2: add support for atomic ops on pre-ARMv6 SMP systems
Patch from Nicolas Pitre
Not that there might be many of them on the planet, but at least RMK
apparently has one.
Signed-off-by: Nicolas Pitre
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index ade0e222..3fefb43 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -422,3 +422,11 @@
assume directly accessing that register and always obtain the
expected value only on ARMv7 and above.
+config NEEDS_SYSCALL_FOR_CMPXCHG
+ bool
+ default y if SMP && (CPU_32v5 || CPU_32v4 || CPU_32v3)
+ help
+ SMP on a pre-ARMv6 processor? Well OK then.
+ Forget about fast user space cmpxchg support.
+ It is just not possible.
+