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

[Anthony Liguori <anthony@codemonkey.ws>]

Markus Armbruster wrote:
> Juan Quintela <quintela@redhat.com> writes:
>
>   
>> Paul Brook <paul@codesourcery.com> 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