mirror of
https://github.com/qemu/qemu.git
synced 2026-07-08 17:46:10 +00:00
feeef57ca0
When debugging issues in KVM guests, it is sometimes helpful to have a
unified trace log of both guest and host to see where things are going
wrong. Expose the TB (timebase) offset through QEMU monitor to enable
capturing of unified log.
The below steps can be then used for KVM guests to get a unified log:
1. In host
trace-cmd record -e kvm_hv:kvm_guest_enter -e kvm_hv:kvm_guest_exit \
-C ppc-tb -o trace_host.dat
2. In guest
trace-cmd record -e powerpc:hcall_entry -e powerpc:hcall_exit -C ppc-tb \
--ts-offset <TB offset from QEMU monitor> -o trace_guest.dat
NOTE: The TB offset would be reported as a negative number in QEMU
monitor. For this step, the minus sign must be ignored.
3. Transfer the guest logs to the host with scp/rsync
4. Unify the logs
trace-cmd report -i trace_host.dat -i trace_guest.dat > combined_log
In case of TCG guests, the TB offset would be
reported as 0 since the offset logic is not applicable in this case.
Tested-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Reviewed-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Reviewed-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Signed-off-by: Gautam Menghani <gautam@linux.ibm.com>
Tested-by: Sneh Shikha Yadav <syadav@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20260629052602.78276-1-gautam@linux.ibm.com
Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>