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Subject[PATCH v2 07/10] coresight: trbe: Do not truncate buffer on IRQ
The TRBE driver marks the AUX buffer as TRUNCATED when we get an IRQ
on FILL event. This has rather unwanted side-effect of the event
being disabled when there may be more space in the ring buffer.

So, instead of TRUNCATE we need a different flag to indicate
that the trace may have lost a few bytes (i.e from the point of
generating the FILL event until the IRQ is consumed). Anyways, the
userspace must use the size from RECORD_AUX headers to restrict
the "trace" decoding.

Using PARTIAL flag causes the perf tool to generate the
following warning:

AUX data had gaps in it XX times out of YY!

Are you running a KVM guest in the background?

which is pointlessly scary for a user. The other remaining options
are :
- COLLISION - Use by SPE to indicate samples collided
- Add a new flag - Specifically for CoreSight, doesn't sound
so good, if we can re-use something.

Given that we don't already use the "COLLISION" flag, the above
behavior can be notified using this flag for CoreSight.

Cc: Mathieu Poirier <>
Cc: James Clark <>
Cc: Mike Leach <>
Cc: Anshuman Khandual <>
Cc: Leo Yan <>
Signed-off-by: Suzuki K Poulose <>
drivers/hwtracing/coresight/coresight-trbe.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 503bea0137ae..d50f142e86d1 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -615,7 +615,7 @@ static unsigned long arm_trbe_update_buffer(struct coresight_device *csdev,
* for correct size. Also, mark the buffer truncated.
write = get_trbe_limit_pointer();
- perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
+ perf_aux_output_flag(handle, PERF_AUX_FLAG_COLLISION);

offset = write - base;
@@ -708,7 +708,7 @@ static void trbe_handle_overflow(struct perf_output_handle *handle)
* collection upon the WRAP event, without stopping the source.
perf_aux_output_flag(handle, PERF_AUX_FLAG_CORESIGHT_FORMAT_RAW |
perf_aux_output_end(handle, size);
event_data = perf_aux_output_begin(handle, event);
if (!event_data) {
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