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Re: [Qemu-devel] [PATCH v3 00/19] reverse debugging
From: |
Ciro Santilli |
Subject: |
Re: [Qemu-devel] [PATCH v3 00/19] reverse debugging |
Date: |
Wed, 23 May 2018 14:23:24 +0100 |
On Wed, May 23, 2018 at 7:49 AM, Pavel Dovgalyuk
<address@hidden> wrote:
> 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-180428
>
This branch appears to contain one month old commits, is it the correct one?
> 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
- [Qemu-devel] [PATCH v3 10/19] replay: implement replay-seek command to proceed to the desired step, (continued)
- [Qemu-devel] [PATCH v3 10/19] replay: implement replay-seek command to proceed to the desired step, Pavel Dovgalyuk, 2018/05/23
- [Qemu-devel] [PATCH v3 11/19] replay: flush events when exiting, Pavel Dovgalyuk, 2018/05/23
- [Qemu-devel] [PATCH v3 13/19] replay: refine replay-time module, Pavel Dovgalyuk, 2018/05/23
- [Qemu-devel] [PATCH v3 12/19] timer: remove replay clock probe in deadline calculation, Pavel Dovgalyuk, 2018/05/23
- [Qemu-devel] [PATCH v3 14/19] translator: fix breakpoint processing, Pavel Dovgalyuk, 2018/05/23
- [Qemu-devel] [PATCH v3 15/19] replay: flush rr queue before loading the vmstate, Pavel Dovgalyuk, 2018/05/23
- [Qemu-devel] [PATCH v3 16/19] gdbstub: add reverse step support in replay mode, Pavel Dovgalyuk, 2018/05/23
- [Qemu-devel] [PATCH v3 17/19] gdbstub: add reverse continue support in replay mode, Pavel Dovgalyuk, 2018/05/23
- [Qemu-devel] [PATCH v3 18/19] replay: describe reverse debugging in docs/replay.txt, Pavel Dovgalyuk, 2018/05/23
- [Qemu-devel] [PATCH v3 19/19] replay: allow loading any snapshots before recording, Pavel Dovgalyuk, 2018/05/23
- Re: [Qemu-devel] [PATCH v3 00/19] reverse debugging,
Ciro Santilli <=