Re: [Qemu-devel] [RFC PATCH v2 00/19] reverse debugging

[Pavel Dovgalyuk]

I'll try to reproduce it next week.

⁣Отправлено с помощью BlueMail ​

На 30 Апр 2018 г., 17:20, в 17:20, Ciro Santilli <address@hidden> написал:п>Did 
you manage to reproduce and solve the savevm and loadvm problems I
>mentioned at:
>http://lists.nongnu.org/archive/html/qemu-devel/2018-04/msg05219.html
>?
>
>I still observe them on the current patch.
>
>On Sat, Apr 28, 2018 at 1:36 PM, 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
>>
>> 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 exitting
>>       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    |    8 +
>>  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, 695 insertions(+), 81 deletions(-)
>>  create mode 100644 replay/replay-debugging.c
>>
>> --
>> Pavel Dovgalyuk