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Diffstat (limited to 'gitlab/issues/target_missing/host_missing/accel_TCG/2791.toml')
| -rw-r--r-- | gitlab/issues/target_missing/host_missing/accel_TCG/2791.toml | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/gitlab/issues/target_missing/host_missing/accel_TCG/2791.toml b/gitlab/issues/target_missing/host_missing/accel_TCG/2791.toml new file mode 100644 index 000000000..bfbbb0416 --- /dev/null +++ b/gitlab/issues/target_missing/host_missing/accel_TCG/2791.toml @@ -0,0 +1,75 @@ +id = 2791 +title = "\"Missing character write event in the replay log\" when trying rr=replay with snapshot" +state = "opened" +created_at = "2025-01-23T16:07:25.357Z" +closed_at = "n/a" +labels = ["accel: TCG", "icount"] +url = "https://gitlab.com/qemu-project/qemu/-/issues/2791" +host-os = "Debian testing" +host-arch = "x86" +qemu-version = "Built from `cf86770c7aa31ebd6e56f4eeb25c34107f92c51e" +guest-os = "n/a" +guest-arch = "n/a" +description = """Probably best to just illustrate with commands. Happy path: + +```sh +rm replay.bin snapshots.qcow2; qemu-img create -f qcow2 snapshots.qcow2 256M + +~/src/qemu/build/qemu-system-x86_64 -nodefaults -nographic -serial stdio \\ + -icount shift=auto,rr=record,rrfile=replay.bin,rrsnapshot=init \\ + -drive file=snapshots.qcow2,if=none,id=rr \\ + -kernel ./.kunit/arch/x86/boot/bzImage -append "nokaslr console=ttyS0" + +# It runs, guest kernel crashes when realising it has no rootfs, all good +du -sh snapshots.qcow2 # 976K + +# Repeat same command just switched to rr=replay +~/src/qemu/build/qemu-system-x86_64 -nodefaults -nographic -serial stdio \\ + -icount shift=auto,rr=replay,rrfile=replay.bin,rrsnapshot=init \\ + -drive file=snapshots.qcow2,if=none,id=rr \\ + -kernel ./.kunit/arch/x86/boot/bzImage -append "nokaslr console=ttyS0" +# Much slower, but same result. All good +``` + +But, I want to take a snapshot later in boot. + +```sh +rm replay.bin snapshots.qcow2; qemu-img create -f qcow2 snapshots.qcow2 256M + +# This time, running with debug. Also have to switch to -monitor stdio because of +# https://gitlab.com/qemu-project/qemu/-/issues/2790 +~/src/qemu/build/qemu-system-x86_64 -nodefaults -nographic -monitor stdio \\ + -icount shift=auto,rr=record,rrfile=replay.bin,rrsnapshot=init \\ + -drive file=snapshots.qcow2,if=none,id=rr \\ + -kernel ./.kunit/arch/x86/boot/bzImage -append "nokaslr console=ttyS0" \\ + -s -S + +# In another terminal, attach a debugger, set a breakpoint, continue to the breakpoint +gdb -ex "target remote localhost:1234" .kunit/vmlinux +(gdb) hb start_kernel +(gdb) continue + +# When the breakpoint is hit, back in the first terminal: +(qemu) savevm test +(qemu) quit + +du -sh snapshots.qcow2 # 21M + +# Now try to replay again +~/src/qemu/build/qemu-system-x86_64 -nodefaults -nographic -serial stdio \\ + -icount shift=auto,rr=replay,rrfile=replay.bin,rrsnapshot=init \\ + -drive file=snapshots.qcow2,if=none,id=rr \\ + -kernel ./.kunit/arch/x86/boot/bzImage -append "nokaslr console=ttyS0" +``` + +Result: + +``` +qemu-system-x86_64: Missing character write event in the replay log (insn total 1598039/586 left, event 886 is EVENT_INSTRUCTION) +fish: Job 1, '~/src/qemu/build/qemu-system-x8…' terminated by signal -icount shift=auto,rr=repla… ( -drive file=snapshots.qcow2…) +fish: Job -kernel ./.kunit/arch/x86/b…, 'SIGABRT' terminated by signal Abort () +``` + +Exit code is 134.""" +reproduce = "n/a" +additional = "n/a" |