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authorStuart Menefy <stuart.menefy@st.com>2007-11-30 16:12:36 +0900
committerPaul Mundt <lethal@linux-sh.org>2008-01-28 13:18:58 +0900
commit1efe4ce3ca126da77e450d5a83f7201949d76f62 (patch)
treefbae9902aa4103a9e86d06f841d580f24682e7b3 /arch/sh/Kconfig
parent53ff09422e5e7a6d6198b767c8f494e43ec8e3ae (diff)
sh: GUSA atomic rollback support.
This implements kernel-level atomic rollback built on top of gUSA, as an alternative non-IRQ based atomicity method. This is generally a faster method for platforms that are lacking the LL/SC pairs that SH-4A and later use, and is only supportable on legacy cores. Signed-off-by: Stuart Menefy <stuart.menefy@st.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'arch/sh/Kconfig')
-rw-r--r--arch/sh/Kconfig12
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 2dc3b177193c..f645f8416f1c 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -692,7 +692,7 @@ source "kernel/Kconfig.preempt"
config GUSA
def_bool y
- depends on !SMP
+ depends on !SMP && SUPERH32
help
This enables support for gUSA (general UserSpace Atomicity).
This is the default implementation for both UP and non-ll/sc
@@ -704,6 +704,16 @@ config GUSA
This should only be disabled for special cases where alternate
atomicity implementations exist.
+config GUSA_RB
+ bool "Implement atomic operations by roll-back (gRB) (EXPERIMENTAL)"
+ depends on GUSA && CPU_SH3 || (CPU_SH4 && !CPU_SH4A)
+ help
+ Enabling this option will allow the kernel to implement some
+ atomic operations using a software implemention of load-locked/
+ store-conditional (LLSC). On machines which do not have hardware
+ LLSC, this should be more efficient than the other alternative of
+ disabling insterrupts around the atomic sequence.
+
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