Re: [Qemu-devel] [PATCH v1 2/2] make: fix help message reference to bogus V=0 variable

[Daniel P. Berrange]

On Tue, Jan 23, 2018 at 01:05:31PM -0600, Eric Blake wrote:
> On 01/23/2018 10:47 AM, Daniel P. Berrange wrote:
> > The make rules for building QEMU are mostly silent by default. They can
> > be made verbose by setting the variable V=1. The default state does not
> > however correspond to a V=0 setting - $(V) must be undefined / empty to
> > get the default quiet build.
> 
> Makefiles generated by automake support V=0; how hard would it be to
> instead tweak things so that 'V=' and 'V=0' have the same effect?

Well it would make the various conmditionals a bit more complex because
we'd have to check three states instead of two. I'm not really convinced
it is worth it because explicitly passing V=0 doesn't do anything useful
given that we are unconditionally silent by default.

It makes more sense with autoconf, because the default behaviour may vary
based on configure setup and/or configure args, so you can't assume that
omitting 'V=' gives you silent build like we do with QEMU.

> 
> > 
> > Signed-off-by: Daniel P. Berrange <address@hidden>
> > ---
> >  Makefile | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Makefile b/Makefile
> > index c263190b8d..554ba69ced 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -940,4 +940,5 @@ ifdef QEMU_GA_MSI_ENABLED
> >  endif
> >     @echo  ''
> >  endif
> > -   @echo  '  $(MAKE) V=0|1 [targets] 0 => quiet build (default), 1 => 
> > verbose build'
> > +   @echo  '  $(MAKE) [targets]      (quiet build, default)'
> > +   @echo  '  $(MAKE) V=1 [targets]  (verbose build)'
> > 
> 
> -- 
> Eric Blake, Principal Software Engineer
> Red Hat, Inc.           +1-919-301-3266
> Virtualization:  qemu.org | libvirt.org
> 




Regards,
Daniel
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