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Re: [Qemu-devel] What's the intended use of log.h logging?
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] What's the intended use of log.h logging? |
Date: |
Mon, 19 Oct 2015 17:57:12 +0100 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
* Peter Maydell (address@hidden) wrote:
> On 19 October 2015 at 15:29, Markus Armbruster <address@hidden> wrote:
> > Points I'd like to make:
> >
> > 1. Logging is not tracing. Logging logs events interesting for the
> > user. Tracing logs code execution. It's a debugging aid. The two
> > overlap to a degree, but they're not the same.
>
> In the case of QEMU, the event the user is often interested in
> is (guest) code execution...
>
> > 2. The current use of log.h seems closer to tracing than to logging.
>
> Maybe. It gets a fair amount of use for "figure out what my
> guest is doing" questions.
>
> > 3. I figure our tracing needs could be served by the tracing subsystem
> > with a few improvements. The few things log.h can do that tracing can't
> > yet do should be easy enough to add. Why have two separate subsystems
> > then?
>
> I just feel that the logging subsystem is very simple and easy
> to use. The tracing subsystem is far from easy to comprehend.
> I'm apprehensive that in the name of simplification we'll end up
> deleting the easy to use logging without making the tracing
> as easy for end users to use.
When I first looked at it, I thought the same way, but then
I found the stderr mode, and it's really very easy.
Dave
> > 4. Logging would be useful, but I feel it shouldn't be shoehorned into
> > log.h.
>
> The log.h code is definitely intended for our end users to run.
> It's true that at the moment we log the things that are easy
> to log rather than having the flexibility to log the things
> end users would ideally like; but the solution to that is to
> improve the logging...
>
> In particular, ideally the logging should allow you to debug or
> instrument your guest program without having to care about QEMU's
> internals particularly. LOG_UNIMP and LOG_GUEST_ERROR are moving
> in that direction.
>
> thanks
> -- PMM
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- 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?, 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, 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?,
Dr. David Alan Gilbert <=
- 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
- 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, 2015/10/21
- 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, 2015/10/22
- Re: [Qemu-devel] What's the intended use of log.h logging?, Paolo Bonzini, 2015/10/22