Hi
I am trying to get qemu events using ftrace but not seeing any events in the
ftrace logs. I see kvm logs like the following but no qemu events such as virtio
blk events. I'm using a locally compiled qemu version with ftrace
backend enabled.
[001] d... 9290.926939: kvm_exit: reason HLT rip 0xffffffff81058e95 info 0 0
This is how I am enabling ftrace logs:
echo 1 >/sys/kernel/debug/tracing/events/kvm/enable
echo 1 > /sys/kernel/debug/tracing/tracing_on
# run cmd
$CMD
# disable trace
echo 0 >/sys/kernel/debug/tracing/events/kvm/enable
echo 0 > /sys/kernel/debug/tracing/tracing_on
# copy trace
echo Copying trace to $outfile
cp /sys/kernel/debug/tracing/trace $outfile
To debug, I build qemu with the 'log' backend, and I am able to see the
appropriate events in /var/log/libvirt log files.
However if I rebuild qemu with ftrace backend, I don't see any events. Do I need
to enable any other tracing events in /sys/kernel/debug/tracing? Do I need to
run any qemu monitor cmds?
Any thing obvious I may be missing? Any debug steps recommended?
I also tried using the simpletrace backend, but I am not sure where the trace
files are created. I am using libvirt and /proc for the qemu process shows the
cwd as '/' - I'm not sure what's supposed to happen here. Is it possible to
collect simpletrace traces using libvirt?
Thanks
Prasun
