Re: [PATCH] gnu: cross-libc: Cross build the correct libc for GNU/Hurd systems.

[ludo@gnu.org (Ludovic Courtès)]

Hi!

Manolis Ragkousis <manolis837@gmail.com> skribis:

> On 06/12/16 19:38, Ludovic Courtès wrote:
>> Could you move this procedure, as well as xgnumach-headers and co., to
>> the top level?  That way there’d be less “clutter” in the definition of
>> ‘cross-libc’ itself.  WDYT?
>
> I created (guix build cross-base) which exports cross-mig,
> cross-kernel-headers and cross-libc-for-target, which is what we need to
> produce a working cross-libc.  Cross-mig is only used when target is
> GNU/Hurd.

The (guix build …) name space is meant for “build-side” code (info
"(guix) G-Expressions"), whereas this is clearly “host” code since it
manipulates packages.  So I think it should remain in (gnu packages
cross-base), only moved to the top-level instead of inner definitions.

Sorry if I wasn’t clear!

>> Other than that it LGTM, but if, and only if, you can verify that this
>> does not cause any regression for other cross-compilation targets.
>> Normally this should not change derivations at all so you don’t even
>> need to build them.  Just run this:
>> 
>>   ./pre-inst-env guix build gcc --target=mips64el-linux-gnu -d
>> 
>> both before and after the change, and the result should be the same .drv
>> file name.
>
> The derivations are not the same

Bah, I was wrong: it’s expected that derivations are not the same since
there are changes like adding KERNEL/lib to CROSS_LIBRARY_PATH.
Apologies for the confusion.

> so I will have to build it and see if it works. I will report back on
> that.

GCC 6 currently fails to cross build.  For a known-good compiler, try
4.9, which currently cross-builds successfully (on master):

--8<---------------cut here---------------start------------->8---
$ ./pre-inst-env guix build gcc@4 --target=mips64el-linux-gnu -n --no-grafts
guix build: warning: ambiguous package specification `gcc@4'
guix build: warning: choosing gcc-4.9.3 from gnu/packages/gcc.scm:334:2
La jenaj derivoj estus elŝutataj:
   /gnu/store/v2rglm6dp21c33lhbcvdzqfsxlxya9qp-gcc-4.9.3-debug
   /gnu/store/aarlmyjnd5hrd3gvi6qwmlsajvvvfnxw-gcc-4.9.3-lib
   /gnu/store/56cl18prjn8rhvjp1y7agwn5gis27h87-gcc-4.9.3
   /gnu/store/1j8pbr9xlzkjx93xvv12z2zflnbw86bg-gmp-6.1.0
   /gnu/store/3m8pj7dc10a9m6ds6gwn198a3d7zjr2a-zlib-1.2.8
   /gnu/store/5cr66jcq6m4qm5nqah6lplby8vli6h2b-isl-0.11.1
   /gnu/store/6kkhcyj1i1bg83h8zx7mrvkp1bfnh8l9-gcc-cross-mips64el-linux-gnu-4.9.3
   /gnu/store/9szbxfc2pizaznklqmas7r8qghqidci6-mpc-1.0.3
   /gnu/store/ac5yx4spq4i78085yy9sxhzr9zrsvhic-glibc-cross-mips64el-linux-gnu-2.22
   /gnu/store/mfn9wr2yl3yq02b87zf1b9vg6n7g9bfw-mpfr-3.1.3
   /gnu/store/n2pc3fzq1fwpbmb83g7kmsj80fa1nld9-cloog-0.18.0
   /gnu/store/7y12yppfwy0ll99faazp2qsank4nmd3j-gcc-cross-sans-libc-mips64el-linux-gnu-4.9.3
$ git describe
v0.10.0-1526-g9dd674d
--8<---------------cut here---------------end--------------->8---

Could you send an updated patch?

Sorry for the delay and all again!

Ludo’.