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authorRussell King <rmk+kernel@arm.linux.org.uk>2011-01-31 14:43:25 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-02-23 17:24:18 +0000
commit74c25beeb30fa32badf575a908902cbdef4d4eb4 (patch)
tree2b059cb3b4f6341770683edebd1329d342ecd219 /arch/arm/vfp
parentaaa50048f6ce44af66ce0389d4cc6a8348333271 (diff)
downloadlwn-74c25beeb30fa32badf575a908902cbdef4d4eb4.tar.gz
lwn-74c25beeb30fa32badf575a908902cbdef4d4eb4.zip
ARM: vfp: improve commentry for hotplug events
Improve the documentation for the VFP hotplug notifier handler, so that people better understand what's going on there and what has been done for them. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/vfp')
-rw-r--r--arch/arm/vfp/vfpmodule.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 25b89d817105..bbf3da012afd 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -489,8 +489,11 @@ void vfp_flush_hwstate(struct thread_info *thread)
/*
* VFP hardware can lose all context when a CPU goes offline.
- * Safely clear our held state when a CPU has been killed, and
- * re-enable access to VFP when the CPU comes back online.
+ * As we will be running in SMP mode with CPU hotplug, we will save the
+ * hardware state at every thread switch. We clear our held state when
+ * a CPU has been killed, indicating that the VFP hardware doesn't contain
+ * a threads VFP state. When a CPU starts up, we re-enable access to the
+ * VFP hardware.
*
* Both CPU_DYING and CPU_STARTING are called on the CPU which
* is being offlined/onlined.