* [Qemu-devel] [PATCH for-2.3] softmmu: clarify meaning of TLB_NOTDIRTY bit
@ 2014-11-26 16:50 Stefan Hajnoczi
0 siblings, 0 replies; only message in thread
From: Stefan Hajnoczi @ 2014-11-26 16:50 UTC (permalink / raw)
To: qemu-devel; +Cc: Peter Maydell, Andreas Färber, Stefan Hajnoczi, rth
It wasn't obvious to me why the TLB entries should cache the memory
dirty bitmap state.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
include/exec/cpu-all.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h
index c085804..e71e47e 100644
--- a/include/exec/cpu-all.h
+++ b/include/exec/cpu-all.h
@@ -329,7 +329,8 @@ extern RAMList ram_list;
/* Zero if TLB entry is valid. */
#define TLB_INVALID_MASK (1 << 3)
/* Set if TLB entry references a clean RAM page. The iotlb entry will
- contain the page physical address. */
+ contain the page physical address. Forces us to take the slow path so pages
+ get marked dirty, whereas the fast path does not mark pages dirty. */
#define TLB_NOTDIRTY (1 << 4)
/* Set if TLB entry is an IO callback. */
#define TLB_MMIO (1 << 5)
--
2.1.0
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2014-11-26 16:50 UTC | newest]
Thread overview: (only message) (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2014-11-26 16:50 [Qemu-devel] [PATCH for-2.3] softmmu: clarify meaning of TLB_NOTDIRTY bit Stefan Hajnoczi
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).