Re: [Qemu-devel] [PATCH] trace: ensure $(tracetool-y) is defined in top level makefile

[Daniel P. Berrange]

On Wed, Mar 15, 2017 at 06:44:25AM -0500, Eric Blake wrote:
> On 03/15/2017 05:56 AM, Daniel P. Berrange wrote:
> > The build rules for trace files have a dependancy on $(tracetool-y).
> > This variable populated in the trace/Makefile.objs file and thus its
> > definition gets pulled into the top level makefile. This happens too
> > late in the process though, so by the time $(tracetool-y) is defined,
> > make has already evaluated $(tracetool-y) in the dependancies and
> > found it to be empty. The result is that when the tracetool source
> > is changed, the generated files are not rebuilt. The solution is to
> > define the variable in the top level makefile too
> > 
> > Signed-off-by: Daniel P. Berrange <address@hidden>
> > ---
> >  Makefile | 3 +++
> >  1 file changed, 3 insertions(+)
> 
> Does this mean the definitions in trace/Makefile.objs are now redundant
> and can be omitted?

Hmm, I'm not sure, but quite possibly true.

> 
> > 
> > diff --git a/Makefile b/Makefile
> > index 1c4c04f..dffc74b 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -85,6 +85,9 @@ GENERATED_SOURCES += $(TRACE_SOURCES)
> >  
> >  trace-group-name = $(shell dirname $1 | sed -e 's/[^a-zA-Z0-9]/_/g')
> >  
> > +tracetool-y = $(SRC_PATH)/scripts/tracetool.py
> > +tracetool-y += $(shell find $(SRC_PATH)/scripts/tracetool -name "*.py")
> 
> Should this also include the comment currently in trace/Makefile.objs:
> 
> ######################################################################
> # tracetool source files
> # Every rule that invokes tracetool must depend on this so code is
> regenerated
> # if tracetool itself changes.
> 
> But it certainly looks like you're on the right track for fixing the
> issue I ran into.

IMHO such comments are pointless - they're just stating the obvious.

Regards,
Daniel
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