Re: [Qemu-devel] [PATCH v6 09/25] replay: introduce info hmp/qmp command

[Pavel Dovgalyuk]

> From: Markus Armbruster [mailto:address@hidden
> Pavel Dovgalyuk <address@hidden> writes:
> 
> > This patch introduces 'info replay' monitor command and
> > corresponding qmp request.
> > These commands request the current record/replay mode, replay log file name,
> > and the execution step (number or recorded/replayed instructions).
> 
> Excuse my ignorant question, please: can you give us an idea what the
> client would do with the execution step?

I know about two use cases:
 1. Control current step to be sure that replay is not stalled due to the bug.
 2. Requesting the step for some moment of execution to use it as a parameter
    of replay_seek/replay_break operations. I.e., for returning to the same
    point later.

> 
> > Signed-off-by: Pavel Dovgalyuk <address@hidden>
> > Acked-by: Dr. David Alan Gilbert <address@hidden>
> >
> > --
> >
> > v2:
> >  - renamed info_replay qmp into query-replay (suggested by Eric Blake)
> > ---
> >  hmp-commands-info.hx      |   14 ++++++++++++++
> >  hmp.h                     |    1 +
> >  qapi/misc.json            |   35 +++++++++++++++++++++++++++++++++++
> >  replay/Makefile.objs      |    3 ++-
> >  replay/replay-debugging.c |   41 +++++++++++++++++++++++++++++++++++++++++
> >  5 files changed, 93 insertions(+), 1 deletion(-)
> >  create mode 100644 replay/replay-debugging.c
> >
> > diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
> > index cbee8b9..9f2f35e 100644
> > --- a/hmp-commands-info.hx
> > +++ b/hmp-commands-info.hx
> > @@ -918,6 +918,20 @@ STEXI
> >  Show SEV information.
> >  ETEXI
> >
> > +    {
> > +        .name       = "replay",
> > +        .args_type  = "",
> > +        .params     = "",
> > +        .help       = "show parameters of the record/replay",
> > +        .cmd        = hmp_info_replay,
> > +    },
> > +
> > +STEXI
> > address@hidden info replay
> > address@hidden info replay
> > +Display the current record/replay mode and the currently executing step.
> > +ETEXI
> > +
> >  STEXI
> >  @end table
> >  ETEXI
> > diff --git a/hmp.h b/hmp.h
> > index 5f1addc..d792149 100644
> > --- a/hmp.h
> > +++ b/hmp.h
> > @@ -148,5 +148,6 @@ void hmp_hotpluggable_cpus(Monitor *mon, const QDict 
> > *qdict);
> >  void hmp_info_vm_generation_id(Monitor *mon, const QDict *qdict);
> >  void hmp_info_memory_size_summary(Monitor *mon, const QDict *qdict);
> >  void hmp_info_sev(Monitor *mon, const QDict *qdict);
> > +void hmp_info_replay(Monitor *mon, const QDict *qdict);
> >
> >  #endif
> > diff --git a/qapi/misc.json b/qapi/misc.json
> > index d450cfe..e246ce3 100644
> > --- a/qapi/misc.json
> > +++ b/qapi/misc.json
> > @@ -3100,6 +3100,41 @@
> >    'data': [ 'none', 'record', 'play' ] }
> >
> >  ##
> > +# @ReplayInfo:
> > +#
> > +# Status of the record/replay mode.
> > +#
> > +# @mode: current mode.
> > +#
> > +# @filename: name of the record/replay log file.
> > +#
> > +# @step: current step number.
> > +#
> > +# Since: 3.1
> > +#
> > +##
> > +{ 'struct': 'ReplayInfo',
> > +  'data': { 'mode': 'ReplayMode', '*filename': 'str', 'step': 'int' } }
> > +
> > +##
> > +# @query-replay:
> > +#
> > +# Retrieves the status of the execution record/replay.
> > +#
> > +# Returns: structure with the properties of the record/replay.
> > +#
> > +# Since: 3.1
> > +#
> > +# Example:
> > +#
> > +# -> { "execute": "query-replay" }
> > +# <- { "return": { "mode": "play", "filename": "log.rr", "step": 220414 } }
> > +#
> > +##
> > +{ 'command': 'query-replay',
> > +  'returns': 'ReplayInfo' }
> > +
> > +##
> >  # @xen-load-devices-state:
> >  #
> >  # Load the state of all devices from file. The RAM and the block devices
> > diff --git a/replay/Makefile.objs b/replay/Makefile.objs
> > index cee6539..6694e3e 100644
> > --- a/replay/Makefile.objs
> > +++ b/replay/Makefile.objs
> > @@ -6,4 +6,5 @@ common-obj-y += replay-input.o
> >  common-obj-y += replay-char.o
> >  common-obj-y += replay-snapshot.o
> >  common-obj-y += replay-net.o
> > -common-obj-y += replay-audio.o
> > \ No newline at end of file
> > +common-obj-y += replay-audio.o
> > +common-obj-y += replay-debugging.o
> > diff --git a/replay/replay-debugging.c b/replay/replay-debugging.c
> > new file mode 100644
> > index 0000000..2d364fa
> > --- /dev/null
> > +++ b/replay/replay-debugging.c
> > @@ -0,0 +1,41 @@
> > +/*
> > + * replay-debugging.c
> > + *
> > + * Copyright (c) 2010-2018 Institute for System Programming
> > + *                         of the Russian Academy of Sciences.
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 or 
> > later.
> > + * See the COPYING file in the top-level directory.
> > + *
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "qapi/error.h"
> > +#include "sysemu/replay.h"
> > +#include "replay-internal.h"
> > +#include "hmp.h"
> > +#include "monitor/monitor.h"
> > +#include "qapi/qapi-commands-misc.h"
> > +
> > +void hmp_info_replay(Monitor *mon, const QDict *qdict)
> > +{
> > +    if (replay_mode == REPLAY_MODE_NONE) {
> > +        monitor_printf(mon, "No record/replay\n");
> > +    } else {
> > +        monitor_printf(mon, "%s execution '%s': current step = 
> > %"PRId64"\n",
> > +            replay_mode == REPLAY_MODE_RECORD ? "Recording" : "Replaying",
> > +            replay_get_filename(), replay_get_current_step());
> > +    }
> > +}
> > +
> > +ReplayInfo *qmp_query_replay(Error **errp)
> > +{
> > +    ReplayInfo *retval = g_new0(ReplayInfo, 1);
> 
> Suggest blank line between declaration and statement.
> 
> > +    retval->mode = replay_mode;
> > +    if (replay_get_filename()) {
> > +        retval->filename = g_strdup(replay_get_filename());
> > +        retval->has_filename = true;
> > +    }
> > +    retval->step = replay_get_current_step();
> > +    return retval;
> > +}

Pavel Dovgalyuk