From mboxrd@z Thu Jan  1 00:00:00 1970
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 10:10:15 +0200
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References: <201608302326.38349.paul@boddie.org.uk> <87inugn1rg.fsf@gnu.org>
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In-Reply-To: <201608312349.49957.paul@boddie.org.uk> (Paul Boddie's message of
	"Wed, 31 Aug 2016 23:49:49 +0200")
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To: Paul Boddie <paul@boddie.org.uk>
Cc: help-guix@gnu.org

Paul Boddie <paul@boddie.org.uk> skribis:

> On Wednesday 31. August 2016 22.04.35 Ludovic Court=C3=A8s wrote:

[...]

>> > I noticed that Arch Linux and its relative Parabola GNU/Linux support =
the
>> > target machine using distcc as a client and having distcc servers cros=
s-
>> > compile code for the target architecture. That seems to require the
>> > coordinating host to be running Arch/Parabola, which then means that s=
ome
>> > bootstrapping needs to be done already. Could a similar thing be done
>> > with GuixSD?
>>=20
>> Yes, using offloading:
>>=20
>>=20=20
>> https://www.gnu.org/software/guix/manual/html_node/Daemon-Offload-Setup.=
html
>>=20
>> If your master node is x86_64 and its machines.scm lists a mips64el
>> machine as in the example above, then =E2=80=9Cguix build foo -s mips64e=
l-linux=E2=80=9D
>> automatically offloads to that mips machine.  (This is the mechanism our
>> hydra.gnu.org build farm uses.)
>
> But this seems like the opposite of the approach in Arch/Parabola: there,=
 the=20
> target machine (mips64el) coordinates the build, with the farm machines=20
> (x86_64) cross-compiling the sources. The benefit is that architectures w=
ith=20
> less powerful hardware can have their packages built for them, but this w=
ould=20
> presumably be contrary to the principles employed by Guix, where native b=
uilds=20
> are mandatory for viability and, I guess, reproducibility reasons.

I should mention that native builds are also subject to offloading.  So
if your main machine is x86_64 and has a machines.scm file that lists
other x86_64 machines, then native builds can be offloaded to them.

If you cross-compile from x86_64, it=E2=80=99s a native build that can be
offloaded to another x86_64 machine.

Hope this clarifies things!

Ludo=E2=80=99.