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From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: Cross-building GuixSD (and maybe using pre-built toolchains)
Date: Thu, 01 Sep 2016 10:17:01 +0200
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	(David Craven's message of "Thu, 1 Sep 2016 00:01:25 +0200")
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To: David Craven <david@craven.ch>
Cc: help-guix@gnu.org

Hi David,

David Craven <david@craven.ch> skribis:

>>> So one issue that happens when cross building is for things that have
>>> the #:no-substitutes #t enabled. This is mainly found in service
>>> derivations for generating configuration files.
>>
>> I think there=E2=80=99s currently no easy way to cross build a full Guix=
SD
>> anyway, like =E2=80=98guix system build --target=3Dmips64el-linux-gnu=E2=
=80=99 (the
>> --target flag doesn=E2=80=99t exist yet).  Or did you experiment in this=
 area?
>>
>> I=E2=80=99d be curious.  It=E2=80=99s designed to allow this (in particu=
lar because
>> gexps are cross-compilation-aware), but I=E2=80=99ve never tried.
>
> I'm currently not trying to cross-compile everything. The
> --system=3Dmips64el-linux gets us pretty far already. The missing parts
> are only the ones where no substitutes are available.

Aaah OK.  That=E2=80=99s not cross-compilation though, so it works if and o=
nly
if substitutes are available or builds can be offloaded to a machine of
that architecture.  Otherwise it cannot really work.

Now, in most cases, the tiny Guile derivations created via
=E2=80=98gexp->derivation=E2=80=99 et al. in GuixSD (e.g., the derivation t=
hat builds
the initrd) could use, say, an x86_64 Guile, even if building for
mips64el.  However, it would be difficult to take advantage of this
AFAICS.

Ludo=E2=80=99.