[PATCH RFC] Use kernel/Kconfig.preempt for ARM

[Uwe Kleine-KÃnig]

before this patch ARM had it's own definition of CONFIG_PREEMPT.
Instead of that use the general definition provided in
kernel/Kconfig.preempt.

It adds some dependencies such that the available options don't change
(neither for ARM nor for other archs).  The only resulting changes are
that ARM gets CONFIG_PREEMPT_NONE and the help text.

Currently the only usage of CONFIG_PREEMPT_NONE is in
kernel/trace/trace.c and only affects the content of some proc files
where "M:unknown" is changed to "M:server" if it is defined.

The intention is that ARM gets the option CONFIG_PREEMPT_RT after it
will be added to kernel/Kconfig.preempt as it is done in the linux-rt
tree.

Signed-off-by: Uwe Kleine-KÃnig <u.kleine-koenig@xxxxxxxxxxxxxx>
Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
---
 arch/arm/Kconfig       |   13 +------------
 kernel/Kconfig.preempt |    2 ++
 2 files changed, 3 insertions(+), 12 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index d6ebe39..941824e 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -838,18 +838,7 @@ config LOCAL_TIMERS
 	  accounting to be spread across the timer interval, preventing a
 	  "thundering herd" at every timer tick.
 
-config PREEMPT
-	bool "Preemptible Kernel (EXPERIMENTAL)"
-	depends on EXPERIMENTAL
-	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.
-	  This allows applications to run more reliably even when the system is
-	  under load.
-
-	  Say Y here if you are building a kernel for a desktop, embedded
-	  or real-time system.  Say N if you are unsure.
+source kernel/Kconfig.preempt
 
 config HZ
 	int
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index bf987b9..03f136b 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -18,6 +18,7 @@ config PREEMPT_NONE
 
 config PREEMPT_VOLUNTARY
 	bool "Voluntary Kernel Preemption (Desktop)"
+	depends on !ARM
 	help
 	  This option reduces the latency of the kernel by adding more
 	  "explicit preemption points" to the kernel code. These new
@@ -35,6 +36,7 @@ config PREEMPT_VOLUNTARY
 
 config PREEMPT
 	bool "Preemptible Kernel (Low-Latency Desktop)"
+	depends on !ARM || EXPERIMENTAL
 	help
 	  This option reduces the latency of the kernel by making
 	  all kernel code (that is not executing in a critical section)
-- 
1.5.6.5

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