From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?utf-8?Q?Ludovic_Court=C3=A8s?= <ludo@gnu.org>
Subject: Re: Starting 'core-updates'?
Date: Tue, 28 Jan 2020 11:47:13 +0100
Message-ID: <87sgjzhn7y.fsf@gnu.org>
References: <87mua8sma4.fsf@devup.no> <87wo9carkj.fsf@gmail.com>
 <8736c0osm0.fsf@cbaines.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Return-path: <guix-devel-bounces+gcggd-guix-devel=m.gmane-mx.org@gnu.org>
Received: from eggs.gnu.org ([2001:470:142:3::10]:51211)
 by lists.gnu.org with esmtp (Exim 4.90_1)
 (envelope-from <ludo@gnu.org>) id 1iwOOs-00072X-Gj
 for guix-devel@gnu.org; Tue, 28 Jan 2020 05:47:19 -0500
In-Reply-To: <8736c0osm0.fsf@cbaines.net> (Christopher Baines's message of
 "Tue, 28 Jan 2020 09:08:55 +0000")
List-Id: "Development of GNU Guix and the GNU System distribution."
 <guix-devel.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/guix-devel>,
 <mailto:guix-devel-request@gnu.org?subject=unsubscribe>
List-Archive: <https://lists.gnu.org/archive/html/guix-devel>
List-Post: <mailto:guix-devel@gnu.org>
List-Help: <mailto:guix-devel-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/guix-devel>,
 <mailto:guix-devel-request@gnu.org?subject=subscribe>
Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane-mx.org@gnu.org
Sender: "Guix-devel"
 <guix-devel-bounces+gcggd-guix-devel=m.gmane-mx.org@gnu.org>
To: Christopher Baines <mail@cbaines.net>
Cc: guix-devel@gnu.org

Hi!

Christopher Baines <mail@cbaines.net> skribis:

> Something I'd be interested in learning more about is
> cross-compilation. The Guix Data Service computes some derivations for
> cross-compilation (see the table on the right of [1] for example), but
> I'm not sure if these are the right one, and because there aren't any
> automated builds for these derivations as far as I'm aware, it's
> difficult to know if they can actually be built.
>
> 1: http://data.guix.gnu.org/revision/ac841750a52e44d68d7f1b02e9507421f3e3=
824f
>
> I'm coming to the Guix Days, so maybe it's something that can be talked
> about then.

Definitely!

The short story though is that there=E2=80=99s confusion between =E2=80=9Cs=
ystem types=E2=80=9D
(like =E2=80=9Cx86-64_linux=E2=80=9D) and GNU triplets (like =E2=80=9Cx86_6=
4-linux-gnu=E2=80=9D,
=E2=80=9Carm-linux-gnueabihf=E2=80=9D, etc.).

The former is used by the daemon as an =E2=80=9Cinput=E2=80=9D, to distingu=
ish
derivations that target different CPUs or different OS kernels.  It=E2=80=
=99s
the option you pass to =E2=80=98guix build -s=E2=80=99.

The latter is used by the GNU toolchain to identify a target system:
CPU, kernel, userland, and optionally hardware vendor.  It=E2=80=99s what y=
ou
pass to =E2=80=98guix build --target=E2=80=99.

(gnu ci) contains the list of cross-compilation targets (triplets) that
we intend to support.  I believe these are those you should be
targeting.  Also, we only even build cross toolchain from =E2=80=9Cx86_64-l=
inux=E2=80=9D
because in practice that=E2=80=99s the only well-tested (and relevant) plat=
form
for that.

Ludo=E2=80=99.