Re: [FFADO-devel] Big changes in trunk

[Jeremy K. <jk...@oz...>]

Hi all,

> Anyway, apart from ranting I'd like to contribute some enhancement to
> the Scontruct file to solve the lib/lib64 issue.
>
> Adding the following lines somewhere early does provide for means to
> distinguish between various CPUs etc. It even works for xcompiles.

[snip]

> Later down you then can change
> env['libdir'] =3D os.path.join( env['PREFIX'], "lib" )
> into
> if config[config_cpu] =3D=3D 'x86_64':
> =A0=A0=A0=A0=A0=A0=A0=A0env['libdir'] =3D os.path.join( env['PREFIX'], "l=
ib64" )
> else:
> =A0=A0=A0=A0=A0=A0=A0=A0env['libdir'] =3D os.path.join( env['PREFIX'], "l=
ib" )

As the token powerpc user here, I feel its my duty to step in - we need=20
to be a little more careful with the issues here.

=46irstly x86_64 isn't the only machine that'll support 64-bit binaries -=20
64-bit powerpc machines will run in both 32- and 64-bit modes, but it's=20
usually up to the distro to choose whether to provide 32- or 64-bit (or=20
both) userland environments. Some do 64-bit only, some 32, some provide=20
both, and use /lib & /lib64 to provide the namespace separation.

And then you have the compilers - some will output 32-bit binaries, some=20
will output 64-bit binaries, some will depend on the -m64 or -m32 flag=20
to determine the target of generated files.

So - $prefix/lib64 should only be used when the actual ELF output is=20
64-bit, and $prefix/lib for 32, regardless of the CPU type. For a=20
pure-64-bit machine, it's also OK to put 64-bit binaries in $prefix/lib=20
(ie, there's no reason to have anything other than one lib dir)

So, one solution may be just to do nothing, and leave it up to the=20
distro packager to specify $libdir correctly when building for a=20
specific target. I think this is the best way to go, as it's really up=20
to the distro to specify the arrangements of libraries for different=20
targets.

Otherwise, we'd need to determine whether this is a 32- or 64-bit build=20
(which isn't trivial), and then fiddle with the paths appropriately.

Just a couple of thoughts :)

Cheers,


Jeremy