From: Stefan Hajnoczi <stefanha@redhat.com>
To: Mads Ynddal <mads@ynddal.dk>
Cc: qemu-devel@nongnu.org, Cleber Rosa <crosa@redhat.com>,
John Snow <jsnow@redhat.com>, Mads Ynddal <m.ynddal@samsung.com>
Subject: Re: [PATCH v2 02/12] simpletrace: Annotate magic constants from QEMU code
Date: Tue, 9 May 2023 10:34:54 -0400 [thread overview]
Message-ID: <20230509143454.GE1008478@fedora> (raw)
In-Reply-To: <20230502092339.27341-3-mads@ynddal.dk>
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On Tue, May 02, 2023 at 11:23:29AM +0200, Mads Ynddal wrote:
> From: Mads Ynddal <m.ynddal@samsung.com>
>
> It wasn't clear where the constants and structs came from, so I added
> comments to help.
>
> Signed-off-by: Mads Ynddal <m.ynddal@samsung.com>
> ---
> scripts/simpletrace.py | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/scripts/simpletrace.py b/scripts/simpletrace.py
> index 9211caaec1..7ba805443d 100755
> --- a/scripts/simpletrace.py
> +++ b/scripts/simpletrace.py
> @@ -15,15 +15,15 @@
> from tracetool import read_events, Event
> from tracetool.backend.simple import is_string
>
> -header_event_id = 0xffffffffffffffff
> -header_magic = 0xf2b177cb0aa429b4
> -dropped_event_id = 0xfffffffffffffffe
> +header_event_id = 0xffffffffffffffff # trace/simple.c::HEADER_EVENT_ID
> +header_magic = 0xf2b177cb0aa429b4 # trace/simple.c::HEADER_MAGIC
> +dropped_event_id = 0xfffffffffffffffe # trace/simple.c::DROPPED_EVENT_ID
>
> -record_type_mapping = 0
> -record_type_event = 1
> +record_type_mapping = 0 # trace/simple.c::TRACE_RECORD_TYPE_MAPPING
> +record_type_event = 1 # trace/simple.c::TRACE_RECORD_TYPE_EVENT
>
> -log_header_fmt = '=QQQ'
> -rec_header_fmt = '=QQII'
> +log_header_fmt = '=QQQ' # trace/simple.c::TraceLogHeader
> +rec_header_fmt = '=QQII' # trace/simple.c::TraceRecord
From my reply to v1 of this patch series:
This is fragile since this information will be outdated if the C source
code changes (e.g. renaming files or variables).
Instead I would add the following comment:
# This is the binary format that the QEMU "simple" trace backend
# emits. There is no specification documentation because the format is
# not guaranteed to be stable. Trace files must be parsed with the
# same trace-events-all file and the same simpletrace.py file that
# QEMU was built with.
I hope that clarifies the scope of the binary format and someone wishing
to look into the format would then know to look at the "simple" trace
backend.
Stefan
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next prev parent reply other threads:[~2023-05-09 14:35 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-02 9:23 [PATCH v2 00/12] simpletrace: refactor and general improvements Mads Ynddal
2023-05-02 9:23 ` [PATCH v2 01/12] simpletrace: Improve parsing of sys.argv; fix files never closed Mads Ynddal
2023-05-04 18:03 ` Stefan Hajnoczi
2023-05-08 13:18 ` Mads Ynddal
2023-05-08 15:08 ` Stefan Hajnoczi
2023-05-02 9:23 ` [PATCH v2 02/12] simpletrace: Annotate magic constants from QEMU code Mads Ynddal
2023-05-09 14:34 ` Stefan Hajnoczi [this message]
2023-05-15 6:51 ` Mads Ynddal
2023-05-02 9:23 ` [PATCH v2 03/12] simpletrace: changed naming of edict and idtoname to improve readability Mads Ynddal
2023-05-09 14:36 ` Stefan Hajnoczi
2023-05-02 9:23 ` [PATCH v2 04/12] simpletrace: update code for Python 3.11 Mads Ynddal
2023-05-09 14:38 ` Stefan Hajnoczi
2023-05-15 6:47 ` Mads Ynddal
2023-05-02 9:23 ` [PATCH v2 05/12] simpletrace: Changed Analyzer class to become context-manager Mads Ynddal
2023-05-09 14:40 ` Stefan Hajnoczi
2023-05-15 7:48 ` Mads Ynddal
2023-05-02 9:23 ` [PATCH v2 06/12] simpletrace: Simplify construction of tracing methods Mads Ynddal
2023-05-09 14:40 ` Stefan Hajnoczi
2023-05-15 8:11 ` Mads Ynddal
2023-05-02 9:23 ` [PATCH v2 07/12] simpletrace: Improved error handling on struct unpack Mads Ynddal
2023-05-02 9:23 ` [PATCH v2 08/12] simpletrace: define exception and add handling Mads Ynddal
2023-05-02 9:23 ` [PATCH v2 09/12] simpletrace: Refactor to separate responsibilities Mads Ynddal
2023-05-02 9:23 ` [PATCH v2 10/12] MAINTAINERS: add maintainer of simpletrace.py Mads Ynddal
2023-05-02 9:23 ` [PATCH v2 11/12] scripts/analyse-locks-simpletrace.py: changed iteritems() to items() Mads Ynddal
2023-05-02 9:23 ` [PATCH v2 12/12] scripts/analyse-locks-simpletrace.py: reflect changes to process in simpletrace.py Mads Ynddal
2023-05-03 13:55 ` [PATCH v2 00/12] simpletrace: refactor and general improvements John Snow
2023-05-08 13:28 ` Mads Ynddal
2023-05-08 15:16 ` Stefan Hajnoczi
2023-05-10 19:14 ` John Snow
2023-05-04 17:48 ` Stefan Hajnoczi
2023-05-04 17:53 ` John Snow
2023-05-08 15:07 ` Stefan Hajnoczi
2023-05-08 16:50 ` Mads Ynddal
2023-05-09 14:33 ` Stefan Hajnoczi
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