Re: [PATCH v3 0/8] [RfC] fix tracing for modules

[Daniel P . Berrangé]

On Fri, Mar 26, 2021 at 01:47:00PM +0100, Gerd Hoffmann wrote:
>   Hi,
> 
> > eg a trace point "dma_map_wait" gets mapped to probes in many
> > .stp files, once per target, because we need to match based on
> > the executable path:
> > 
> >   probe qemu.system.x86_64.dma_map_wait = 
> > process("/usr/libexec/qemu-system-x86_64").mark("dma_map_wait")
> >   probe qemu.system.x86_64.dma_map_wait = 
> > process("/usr/libexec/qemu-system-ppc64").mark("dma_map_wait")
> 
> Probe qemu.system.ppc64.dma_map_wait = ...
> 
> Can I trace qemu started from build directory?
> Seems scripts/qemu-trace-stap doesn't support that.

We should really generate extra equiv .stp files just for running from
the build.

> >   qxl.destroy_primary(int qid) "%d"
> >   qxl.enter_vga_mode(int qid) "%d"
> >   qxl.exit_vga_mode(int qid) "%d"
> > 
> > this would be backwards compatible, as we can turn the "." back into
> > a "_" for all existing trace backends, except stp.
> 
> Hmm, not sure I like this inconsistency.  I think names should be the
> same no matter which trace backend is used.

Regards,
Daniel
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