aubinator.c: In function ‘parse_commands’:
aubinator.c:768:19: warning: suggest parentheses around comparison in operand
of ‘&’ [-Wparentheses]
if (p[0] & (1 << 22) == 0)
-----Original Message-----
From: mesa-dev [mailto:mesa-dev-boun...@lists.freedesktop.org] On Behalf Of
Jason Ekstrand
Sent: Thursday, September 08, 2016 9:12 PM
To: mesa-dev@lists.freedesktop.org
Cc: Ekstrand, Jason <jason.ekstr...@intel.com>
Subject: [Mesa-dev] [PATCH] intel/aubinator: Properly handle batch buffer
chaining
The original aubinator that Kristian wrote had a bug in the handling of
MI_BATCH_BUFFER_START that propagated into the version in upstream mesa.
Say you have two batch buffers A and B where A calls MI_BATCH_BUFFER_START to
jump to B. Now suppose that A and B are placed consecutively in the address
space with A before B. What can happen is that aubinator will process A, and
start processing B when it should. When it gets done with B, it returns and
continues to process A. Because A doesn't have any more data after the
MI_BATCH_BUFFER_START, it will just process a bunch of NOPs until it gets to
the next buffer in memory which is B again. In this scenario B gets processed
twice which can be very confusing. If you place things in memory just right,
you can also end up with infinite loops which are all sorts of fun.
The root problem here is that it continues to process commands even after an
MI_BATCH_BUFFER_START. By simply checking the 2nd level we can detect whether
or not the command buffer we are jumping to will return here and stop
processing commands if it won't.
Signed-off-by: Jason Ekstrand
<ja...@jlekstrand.net<mailto:ja...@jlekstrand.net>>
---
src/intel/tools/aubinator.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/src/intel/tools/aubinator.c b/src/intel/tools/aubinator.c index
fe1f369..73a7f21 100644
--- a/src/intel/tools/aubinator.c
+++ b/src/intel/tools/aubinator.c
@@ -766,6 +766,13 @@ parse_commands(struct gen_spec *spec, uint32_t *cmds, int
size, int engine)
start = p[1];
parse_commands(spec, gtt + start, 1 << 20, engine);
+
+ /* MI_BATCH_BUFFER_START with "2nd Level Batch Buffer" unset acts
+ * like a goto. No commands after such a MI_BATCH_BUFFER_START will
+ * get processed so we should bail as well.
+ */
+ if (p[0] & (1 << 22) == 0)
[SG]: The above line might need extra pair of parenthesis around comparison to
get rid of the compile time warning I was seeing as below. Otherwise, Patch
looks good to me.
aubinator.c: In function ‘parse_commands’:
aubinator.c:768:19: warning: suggest parentheses around comparison in operand
of ‘&’ [-Wparentheses]
if (p[0] & (1 << 22) == 0)
+ break;
} else if ((p[0] & 0xffff0000) == AUB_MI_BATCH_BUFFER_END) {
break;
}
--
2.5.0.400.gff86faf
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