Module: xenomai-3
Branch: next
Commit: 2d65ff2c9b64860b0e9ea6740cbe7c540d634f7b
URL:    
http://git.xenomai.org/?p=xenomai-3.git;a=commit;h=2d65ff2c9b64860b0e9ea6740cbe7c540d634f7b

Author: Philippe Gerum <r...@xenomai.org>
Date:   Sat Nov 14 16:41:13 2015 +0100

cobalt/powerpc: drop support for unlocked context switch

This feature never actually brought any measurable gain on powerpc
platforms, compared to the complexity of its implementation in the
pipeline. It was primarily aimed at reducing latency for interrupt
handlers when costly cache and TLB flushes are required to switch
context, at the expense of increasing the scheduling latency.  It
turned out to be counter-productive on common powerpc platforms, with
efficient MMUs.

This feature has been default off for a while now, and 4.1+ pipelines
won't provide support for it anymore. Time to drop support from
Xenomai too.

---

 kernel/cobalt/arch/powerpc/Kconfig |   20 +-------------------
 1 file changed, 1 insertion(+), 19 deletions(-)

diff --git a/kernel/cobalt/arch/powerpc/Kconfig 
b/kernel/cobalt/arch/powerpc/Kconfig
index 40eae0b..1cabef3 100644
--- a/kernel/cobalt/arch/powerpc/Kconfig
+++ b/kernel/cobalt/arch/powerpc/Kconfig
@@ -5,29 +5,11 @@ config XENO_ARCH_MATH_EMU
         bool
        default y if MATH_EMU || MATH_EMULATION
 
-config IPIPE_WANT_PREEMPTIBLE_SWITCH
-        bool
-       default y if XENO_ARCH_UNLOCKED_SWITCH
-       default n if !XENO_ARCH_UNLOCKED_SWITCH
-
 config XENO_ARCH_FPU
        def_bool PPC_FPU
 
 config XENO_ARCH_SYS3264
         def_bool n
 
-menu "Machine/platform-specific options"
-
 config XENO_ARCH_UNLOCKED_SWITCH
-       bool "Unlocked context switch"
-       depends on IPIPE_HAVE_PREEMPTIBLE_SWITCH
-       default y
-       help
-
-       The Cobalt core may allow non-atomic execution of the
-       machine-dependent context switching code, so that other CPUs
-       and/or local interrupts may execute concurrently.
-
-       This option reduces interrupt latency when costly cache and
-       TLB flushes are required to switch context.
-endmenu
+       def_bool n


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