[PATCH] ppc32: support hotplug cpu on powermacs

This allows cpus to be off-lined on 32-bit SMP powermacs.  When a cpu
is off-lined, it is put into sleep mode with interrupts disabled.  It
can be on-lined again by asserting its soft-reset pin, which is
connected to a GPIO pin.

With this I can off-line the second cpu in my dual G4 powermac, which
means that I can then suspend the machine (the suspend/resume code
refuses to suspend if more than one cpu is online, and making it cope
with multiple cpus is surprisingly messy).

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/ppc/Kconfig b/arch/ppc/Kconfig
index e3f1ce33e642..347ea284140b 100644
--- a/arch/ppc/Kconfig
+++ b/arch/ppc/Kconfig
@@ -265,6 +265,15 @@ config PPC601_SYNC_FIX
 
           If in doubt, say Y here.
 
+config HOTPLUG_CPU
+        bool "Support for enabling/disabling CPUs"
+        depends on SMP && HOTPLUG && EXPERIMENTAL && PPC_PMAC
+        ---help---
+          Say Y here to be able to disable and re-enable individual
+          CPUs at runtime on SMP machines.
+
+          Say N if you are unsure.
+
 source arch/ppc/platforms/4xx/Kconfig
 source arch/ppc/platforms/85xx/Kconfig