Ryan Gambord has submitted this change and it was merged. (
https://gem5-review.googlesource.com/c/public/gem5/+/17508 )
Change subject: cpu-kvm: Added informative error message
......................................................................
cpu-kvm: Added informative error message
PerfKvmCounter::attach fails if the user doesn't have privileges to make
the perf_event_open syscall. This is the default privilege setting since
kernel 4.6. I've seen some users in the mailing list resort to running
as root; changing the perf_event_paranoid setting is an alternative.
Change-Id: I2bc6f76abb6e97bf34b408a611f64b1910f50a43
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17508
Reviewed-by: Andreas Sandberg <[email protected]>
Maintainer: Andreas Sandberg <[email protected]>
---
M src/cpu/kvm/perfevent.cc
1 file changed, 12 insertions(+), 1 deletion(-)
Approvals:
Andreas Sandberg: Looks good to me, approved; Looks good to me, approved
diff --git a/src/cpu/kvm/perfevent.cc b/src/cpu/kvm/perfevent.cc
index 5023b30..0b5960d 100644
--- a/src/cpu/kvm/perfevent.cc
+++ b/src/cpu/kvm/perfevent.cc
@@ -169,7 +169,18 @@
group_fd,
0); // Flags
if (fd == -1)
- panic("PerfKvmCounter::open failed (%i)\n", errno);
+ {
+ if (errno == EACCES)
+ {
+ panic("PerfKvmCounter::attach recieved error EACCESS\n"
+ " This error may be caused by a too restrictive setting\n"
+ " in the file '/proc/sys/kernel/perf_event_paranoid'\n"
+ " The default value was changed to 2 in kernel 4.6\n"
+ " A value greater than 1 prevents gem5 from making\n"
+ " the syscall to perf_event_open");
+ }
+ panic("PerfKvmCounter::attach failed (%i)\n", errno);
+ }
mmapPerf(1);
}
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-Change-Id: I2bc6f76abb6e97bf34b408a611f64b1910f50a43
Gerrit-Change-Number: 17508
Gerrit-PatchSet: 2
Gerrit-Owner: Ryan Gambord <[email protected]>
Gerrit-Reviewer: Andreas Sandberg <[email protected]>
Gerrit-Reviewer: Ryan Gambord <[email protected]>
Gerrit-CC: Jason Lowe-Power <[email protected]>
Gerrit-MessageType: merged
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