[PATCH] uml: mark SMP on UML/x86_64 as broken

Noticed by Al Viro <viro@parcelfarce.linux.theplanet.co.uk> - SMP on x86_64 is
fundamentally broken due to UML's reuse of the host arch's percpu stuff.  This
is OK on x86, but the x86_64 pda stuff just won't work for UML.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index d5e22f0848802ccb6a6a0db17317ec90a48d014d..684e1f8b2755da5c5b2da0ad5e973505aa71a1a7 100644 (file)
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -196,7 +196,7 @@ config HOST_2G_2G
 config SMP
        bool "Symmetric multi-processing support (EXPERIMENTAL)"
        default n
-       depends on MODE_TT && EXPERIMENTAL
+       depends on (MODE_TT && EXPERIMENTAL && !SMP_BROKEN) || (BROKEN && SMP_BROKEN)
        help
        This option enables UML SMP support.
        It is NOT related to having a real SMP box. Not directly, at least.

diff --git a/arch/um/Kconfig.x86_64 b/arch/um/Kconfig.x86_64
index 6e5357c5bcfb690cad5caa50e0abf3a0a331ed30..bd35e59419c8b8ff88aeeb2277a74b875eacc6df 100644 (file)
--- a/arch/um/Kconfig.x86_64
+++ b/arch/um/Kconfig.x86_64
@@ -37,3 +37,7 @@ config ARCH_HAS_SC_SIGNALS
 config ARCH_REUSE_HOST_VSYSCALL_AREA
        bool
        default n
+
+config SMP_BROKEN
+       bool
+       default y