[PATCH] ppc32: Allow PREEMPT with SMP in KConfig

From: Benjamin Herrenschmidt
Date: Tue Mar 30 2004 - 00:44:37 EST

Hi !

On ppc32, CONFIG_PREEMPT wasn't settable along with CONFIG_SMP
for historical reasons (smp_processor_id() races). Those races have
been fixes since then (well, should have been at least) so it's now
safe to allow both options.


===== arch/ppc/Kconfig 1.56 vs edited =====
--- 1.56/arch/ppc/Kconfig Fri Mar 19 17:04:54 2004
+++ edited/arch/ppc/Kconfig Tue Mar 30 15:39:41 2004
@@ -696,14 +696,10 @@

config PREEMPT
bool "Preemptible Kernel"
- depends on !SMP
This option reduces the latency of the kernel when reacting to
real-time or interactive events by allowing a low priority process to
be preempted even if it is in kernel mode executing a system call.
- Unfortunately the kernel code has some race conditions if both
- CONFIG_SMP and CONFIG_PREEMPT are enabled, so this option is
- currently disabled if you are building an SMP kernel.

Say Y here if you are building a kernel for a desktop, embedded
or real-time system. Say N if you are unsure.

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