Re: --multilib

[Dan Kegel <dank at kegel dot com>]

Stuart Hughes wrote:
> > > What I'm trying to work out is if it's possible to have something like
> > > an arm toolchain that supports big-endian and little-endian in soft or
> > > hard float mode.
> >
> > Earlier this year I figured out how to multilib a bit.
> > http://www.kegel.com/xgcc3/gcc-20020715-ppc405erratum77.patch
> > added a way to turn on an extra set of libraries specially
> > compiled for ppc405.  I can't remember how it worked
> > (it's too painful :-) but maybe you can work it out from
> > that patch and from digging in the manual.  ...
>
> I've looked in the manuals (info gcc) and I sort of understand that you
> can get gcc to make multiple versions of its libraries, and then control
> them with flags (e.g -mbig-endian) or with alternate spec files.
> However, what always bothers me is that most toolchains incorporate a C
> library, and as far as I can tell, this is not multi-lib aware and so I
> don't see how you can get the C library to switch.   So for example if
> you build glibc little endian, and then you needed to build a 'hello
> world' big-endian where would the big-endian libc come from ??

You'd have to build it.  Crosstool might loop,
building a libc for each of the multiple library options,
say.  Not sure how that would work out in practice.
It's much simpler to just run crosstool once for each
set of options, and create multiple single-libbed toolchains.
- Dan

--
My technical stuff: http://kegel.com
My politics: see http://www.misleader.org for examples of why I'm for regime change

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