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

[Gerd Hoffmann]

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?

thanks,
  Gerd