Re: [Qemu-devel] Re: [PATCH 00/37] Generate a proper LIBS variable

[Anthony Liguori]

Markus Armbruster wrote:
> Juan Quintela <address@hidden> writes:
>
>   
> > Paul Brook <address@hidden> wrote:
> >     
> > > > I tend to think that using the same libraries for all binaries is a good
> > > > idea, but I think we shouldn't confuse the isues.
> > > >         
> > > Usermode and full system emulation are completely different applications. It 
> > > makes no sense to use the same set of libraries.
> > >       
> > Ok, switching to:
> >
> > libs : for everything
> > libs_softmmu
> > libs_linux
> > libs_bsd
> > libs_darwin
> >
> > ldflags <- similar, not a big problem
> >
> > CFLAGS/CPPFLAGS, this is a whole different can of worms
> >
> > As of know, we have:
> > - OS_FLAGS
> > - ARCH_FLAGS
> > - CFLAGS
> > - CPPFLAGS
> > - CFLAGS for specific files (KVM_CFLAGS and similars)
> > - CFLAGS for some libs that got compiled all files with
> > - HELPER_CFLAGS
> > - SP_FLAGS (already killed on my patches, it is know part of ARCH_FLAGS)
> > - EXTRA_CFLAGS
> >
> > Starting in configure, which flags are used for each test: random mix of
> > CFLAGS + EXTRA_CFLAGS + OS_FLAGS + ARCH_FLAGS
> >
> > Clearly, not an ideal solution.
> >
> > What we want to be able to do:
> > a- let the user add CFLAGS to all the tests and build
> > b- let the user overwrote CFLAGS generated by ./configure + Makefile
> > c- the several files be compiled with diffrent CFLAGS
> > d- let the user change the CFLAGS for a specific file from command line
> >    make; rm foo.o; make CFLAGS=""
> >
> > Solution so far:
> >
> > CPPFLAGS is for stuff that you "really" need, i.e. include paths and
> >          Defines
> > CFLAGS is for the rest of options, that can be "removed"
> >     
>
> Actually, CPPFLAGS is for preprocessor stuff, and CFLAGS for the rest.
>   

It's never followed verbatim though and we'll likely invoke CPP is 
usually just gcc -E.  We can't enforce a hard split between CPPFLAGS and 
CFLAGS when we use things like pkg-config, --cflags only gives us one 
set of flags.

Likewise, it's hard to separate LDFLAGS from LDLIBS too for the same reason.

Regards,

Anthony Liguori