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

[Daniel P . Berrangé]

On Mon, Mar 29, 2021 at 11:48:18AM +0200, Gerd Hoffmann wrote:
> On Mon, Mar 29, 2021 at 10:23:42AM +0100, Daniel P. Berrangé wrote:
> > 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.
> 
> Well, "make install" with --prefix=$HOME/qemu-install fixed that for the time
> being.
> 
> Now I have this:
> 
> kraxel@sirius ~/qemu-install/bin# sudo ./qemu-trace-stap -v run 
> ./qemu-system-x86_64 "qxl_soft_reset"
> Using tapset dir '/home/kraxel/qemu-install/share/systemtap/tapset' for 
> binary './qemu-system-x86_64'
> Compiling script 'probe qemu.system.x86_64.log.qxl_soft_reset {}'
> semantic error: unresolved function pid: identifier 'pid' at 
> /home/kraxel/qemu-install/share/systemtap/tapset/qemu-system-x86_64-log.stp:5451:41
>         source:     printf("%d@%d qxl_soft_reset %d\n", pid(), 
> gettimeofday_ns(), qid)
>                                                         ^
> 
> Pass 2: analysis failed.  [man error::pass2]
> 
> Any clue why pid() isn't known?

Hmm, strange, makes me think we have a bug causing it to not pull in
global functions.

Regards,
Daniel
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