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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Andrew Morton <akpm@osdl.org>
Cc: Linus Torvalds <torvalds@osdl.org>,
	Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: [PATCH] ppc32: Allow PREEMPT with SMP in KConfig
Date: Tue, 30 Mar 2004 15:41:18 +1000	[thread overview]
Message-ID: <1080625278.1213.11.camel@gaston> (raw)

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.

Ben.

===== 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
 	help
 	  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.



                 reply	other threads:[~2004-03-30  5:41 UTC|newest]

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