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Re: [Qemu-devel] What's the intended use of log.h logging? (was: [PATCH
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] What's the intended use of log.h logging? (was: [PATCH 2/3] log: report hmp/qmp command and qmp event) |
Date: |
Fri, 16 Oct 2015 13:51:30 +0100 |
On 16 October 2015 at 13:33, Markus Armbruster <address@hidden> wrote:
> We have a couple of related features, and I'd like to get some clarity
> on how exactly they should be used.
>
> 1. Tracing
>
> Documented in docs/tracing.txt.
>
> Each trace event can be individually controlled with -trace and with
> monitor command trace-event. Wildcards work. Monitor command "info
> trace-event" shows their status.
>
> Supports a wealth of tracing backends: nop (compiles out tracing
> completely), stderr (prints trace to stderr), "simple", "ftrace",
> "dtrace", ... Range from "trivially easy" to "complex power tool".
The major problem with this is it is a compile time choice
(especially the choice of backend), and our default backend
is 'nop'.
> 2. Ad hoc printing
>
> We have 108 files with some #define DPRINTF(), and probably some more
> sailing under different flags. The ones that aren't useless should
> probably be tracepoints.
>
> 3. "qemu/log.h" logging
>
> Sports a "mask", where each bit enables a certain set of log
> messages. Control the mask with "-d item,..." Try "-d help" to see
> acceptable items.
>
> Logs to stderr by default, can be redirected with "-D <logfile>".
This, though it is a bit ad-hoc, always exists, always behaves the
same way, and doesn't require anybody to rebuild QEMU to enable
tracing.
I think having a more consistent approach to logging would be great,
though.
thanks
-- PMM
- Re: [Qemu-devel] What's the intended use of log.h logging?, (continued)
- Re: [Qemu-devel] What's the intended use of log.h logging?, Daniel P. Berrange, 2015/10/16
- Re: [Qemu-devel] What's the intended use of log.h logging?, Peter Maydell, 2015/10/16
- Re: [Qemu-devel] What's the intended use of log.h logging?, Paolo Bonzini, 2015/10/16
- Re: [Qemu-devel] What's the intended use of log.h logging?, Peter Maydell, 2015/10/16
- Re: [Qemu-devel] What's the intended use of log.h logging?, Paolo Bonzini, 2015/10/16
- Re: [Qemu-devel] What's the intended use of log.h logging?, Peter Maydell, 2015/10/16
- Re: [Qemu-devel] What's the intended use of log.h logging?, Paolo Bonzini, 2015/10/16
- Re: [Qemu-devel] What's the intended use of log.h logging?, Markus Armbruster, 2015/10/19
- Re: [Qemu-devel] What's the intended use of log.h logging?, Paolo Bonzini, 2015/10/19
- Re: [Qemu-devel] What's the intended use of log.h logging?, Peter Maydell, 2015/10/19
- Re: [Qemu-devel] What's the intended use of log.h logging? (was: [PATCH 2/3] log: report hmp/qmp command and qmp event),
Peter Maydell <=
- Re: [Qemu-devel] What's the intended use of log.h logging?, Markus Armbruster, 2015/10/19
- Re: [Qemu-devel] What's the intended use of log.h logging?, Peter Maydell, 2015/10/19
- Re: [Qemu-devel] What's the intended use of log.h logging?, Dr. David Alan Gilbert, 2015/10/19
- Re: [Qemu-devel] What's the intended use of log.h logging?, Dr. David Alan Gilbert, 2015/10/19
- Re: [Qemu-devel] What's the intended use of log.h logging?, Kevin Wolf, 2015/10/20
- Re: [Qemu-devel] What's the intended use of log.h logging? (was: [PATCH 2/3] log: report hmp/qmp command and qmp event), Alex Bennée, 2015/10/16
- Re: [Qemu-devel] What's the intended use of log.h logging?, Markus Armbruster, 2015/10/19
- Re: [Qemu-devel] What's the intended use of log.h logging?, Peter Maydell, 2015/10/19
- Re: [Qemu-devel] What's the intended use of log.h logging? (was: [PATCH 2/3] log: report hmp/qmp command and qmp event), Stefan Hajnoczi, 2015/10/21
- Re: [Qemu-devel] What's the intended use of log.h logging?, Denis V. Lunev, 2015/10/21