Pavel Dovgalyuk <pavel.dovga...@ispras.ru> writes:
> Ping? I started having a look but I ran into this straight away. First I recorded a boot of the kernel: ./aarch64-softmmu/qemu-system-aarch64 -machine virt,graphics=on,gic-version=3,virtualization=on -cpu cortex-a53 --serial mon:stdio -display none -kernel ../images/aarch64-current-linux-initrd-guest.img -icount shift=7,rr=record,rrfile=replay.bin Then played back: ./aarch64-softmmu/qemu-system-aarch64 -machine virt,graphics=on,gic-version=3,virtualization=on -cpu cortex-a53 --serial mon:stdio -display none -kernel ../images/aarch64-current-linux-initrd-guest.img -icount shift=7,rr=replay,rrfile=replay.bin -s -S And did the following on gdb: (gdb) i 0x0000000040000004 in ?? () => 0x40000004: mov x1, xzr 0x40000008: mov x2, xzr 0x4000000c: mov x3, xzr (gdb) 0x0000000040000008 in ?? () => 0x40000008: mov x2, xzr 0x4000000c: mov x3, xzr 0x40000010: ldr x4, 0x40000020 (gdb) 0x000000004000000c in ?? () => 0x4000000c: mov x3, xzr 0x40000010: ldr x4, 0x40000020 0x40000014: br x4 (gdb) 0x0000000040000010 in ?? () => 0x40000010: ldr x4, 0x40000020 0x40000014: br x4 0x40000018: .inst 0x44000000 ; undefined (gdb) 0x0000000040000014 in ?? () => 0x40000014: br x4 0x40000018: .inst 0x44000000 ; undefined 0x4000001c: .inst 0x00000000 ; undefined (gdb) p/x $x4 $1 = 0x40080000 (gdb) reverse-stepi warning: Remote failure reply: E14 Surely this is the simple case and doesn't require any snapshots for block devices as there are none. Am I missing something? > > > > Отправлено с помощью BlueMail > > На 28 Май 2018 г., 10:13, в 10:13, Pavel Dovgalyuk <pavel.dovga...@ispras.ru> > написал:п>GDB remote protocol supports reverse debugging of the targets. >>It includes 'reverse step' and 'reverse continue' operations. >>The first one finds the previous step of the execution, >>and the second one is intended to stop at the last breakpoint that >>would happen when the program is executed normally. >> >>Reverse debugging is possible in the replay mode, when at least >>one snapshot was created at the record or replay phase. >>QEMU can use these snapshots for travelling back in time with GDB. >> >>Running the execution in replay mode allows using GDB reverse debugging >>commands: >> - reverse-stepi (or rsi): Steps one instruction to the past. >> QEMU loads on of the prior snapshots and proceeds to the desired >> instruction forward. When that step is reaches, execution stops. >> - reverse-continue (or rc): Runs execution "backwards". >> QEMU tries to find breakpoint or watchpoint by loaded prior snapshot >> and replaying the execution. Then QEMU loads snapshots again and >> replays to the latest breakpoint. When there are no breakpoints in >> the examined section of the execution, QEMU finds one more snapshot >> and tries again. After the first snapshot is processed, execution >> stops at this snapshot. >> >>The set of patches include the following modifications: >> - gdbstub update for reverse debugging support >> - functions that automatically perform reverse step and reverse >> continue operations >> - hmp/qmp commands for manipulating the replay process >> - improvement of the snapshotting for saving the execution step >> in the snapshot parameters >> - other record/replay fixes >> >>The patches are available in the repository: >>https://github.com/ispras/qemu/tree/rr-180524 >> >>v4 changes: >>- changed 'since 2.13' to 'since 3.0' in json (as suggested by Eric >>Blake) >> >>v3 changes: >>- Fixed PS/2 bug with save/load vm, which caused failures of the >>replay. >> The patch was sent separately. >> - Rebased to the new code base. >> - Minor fixes. >> >>v2 changes: >> - documented reverse debugging >> - fixed start vmstate loading in record mode >> - documented qcow2 changes (as suggested by Eric Blake) >> - made icount SnapshotInfo field optional (as suggested by Eric Blake) >> - renamed qmp commands (as suggested by Eric Blake) >> - minor changes >> >>--- >> >>Pavel Dovgalyuk (19): >> block: implement bdrv_snapshot_goto for blkreplay >> replay: disable default snapshot for record/replay >> replay: update docs for record/replay with block devices >> replay: don't drain/flush bdrv queue while RR is working >> replay: finish record/replay before closing the disks >> qcow2: introduce icount field for snapshots >> migration: introduce icount field for snapshots >> replay: introduce info hmp/qmp command >> replay: introduce breakpoint at the specified step >> replay: implement replay-seek command to proceed to the desired step >> replay: flush events when exiting >> timer: remove replay clock probe in deadline calculation >> replay: refine replay-time module >> translator: fix breakpoint processing >> replay: flush rr queue before loading the vmstate >> gdbstub: add reverse step support in replay mode >> gdbstub: add reverse continue support in replay mode >> replay: describe reverse debugging in docs/replay.txt >> replay: allow loading any snapshots before recording >> >> >> accel/tcg/translator.c | 9 + >> block/blkreplay.c | 8 + >> block/io.c | 22 +++ >> block/qapi.c | 17 ++- >> block/qcow2-snapshot.c | 9 + >> block/qcow2.h | 2 >> blockdev.c | 10 ++ >> cpus.c | 19 ++- >> docs/interop/qcow2.txt | 4 + >> docs/replay.txt | 45 +++++++ >> exec.c | 6 + >> gdbstub.c | 50 +++++++- >> hmp-commands-info.hx | 14 ++ >> hmp-commands.hx | 30 +++++ >> hmp.h | 3 >> include/block/snapshot.h | 1 >> include/sysemu/replay.h | 18 +++ >> migration/savevm.c | 15 +- >> qapi/block-core.json | 5 + >> qapi/block.json | 3 >> qapi/misc.json | 68 +++++++++++ >> replay/Makefile.objs | 3 >>replay/replay-debugging.c | 287 >>+++++++++++++++++++++++++++++++++++++++++++++ >> replay/replay-events.c | 14 -- >> replay/replay-internal.h | 10 +- >> replay/replay-snapshot.c | 17 ++- >> replay/replay-time.c | 27 ++-- >> replay/replay.c | 22 +++ >> stubs/replay.c | 10 ++ >> util/qemu-timer.c | 11 -- >> vl.c | 18 ++- >> 31 files changed, 696 insertions(+), 81 deletions(-) >> create mode 100644 replay/replay-debugging.c >> >>-- >>Pavel Dovgalyuk -- Alex Bennée
