[PATCH] enable X86_PC for HOTPLUG_CPU

CPU_HOTPLUG has race conditions when we use broadcast mode IPI.

- First we introduced no_broadcast option
    (see include/asm-i386/mach-default/mach_ipi.h)

- x86_64 solved it by using physical flat mode (same as bigsmp on i386)
  since this will not use broadcast shortcuts for IPI.

- We switched to use bigsmp on i386 so that we can have same handling as
  x86_64, but apparently this caused an error message, if kernel was
  compiled without X86_GENERICARCH, X86_BIGSMP.  The message "You have >8
  CPUS..." which was bogus and misleading, and only indicated one of the
  above ARCH wasnt selected.

So we do not switch to automatic bigsmp for HOTPLUG_CPU support in i386
until the other related config dependencies for SMP_SUSPEND etc can be done
right.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index 18ec9fe6deb69d887a1f48a204c7b126cb633e04..366b401c1f29b4c93148b861495dd9fdacfac90d 100644 (file)
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -756,7 +756,7 @@ config PHYSICAL_START
 
 config HOTPLUG_CPU
        bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
-       depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER && !X86_PC
+       depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER
        ---help---
          Say Y here to experiment with turning CPUs off and on.  CPUs
          can be controlled through /sys/devices/system/cpu.