From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: Offloading to a VM
Date: Mon, 29 Aug 2016 14:54:02 +0200
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	(David Craven's message of "Sun, 28 Aug 2016 16:38:59 +0200")
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To: David Craven <david@craven.ch>
Cc: guix-devel <guix-devel@gnu.org>

David Craven <david@craven.ch> skribis:

>> --8<---------------cut here---------------start------------->8---
>> $ qemu-arm $(guix build coreutils -s armhf-linux |grep -v debug)/bin/una=
me -a
>> Linux pluto 4.7.0-gnu #1 SMP 1 armv7l GNU/Linux
>> $ uname -a
>> Linux pluto 4.7.0-gnu #1 SMP 1 x86_64 GNU/Linux
>> --8<---------------cut here---------------end--------------->8---
>
> If I understand correctly this only works when there is a substitute
> already. If it's a new package for example that would fail with "not
> an armhf system" right?

The =E2=80=9Cbuild hook=E2=80=9D is the mechanism by which the daemon asks =
an external
program whether it can build a derivation for some system.

Our (guix scripts offload) is such a program; it replies positively if
there=E2=80=99s a machine that matches the target system.

What I was suggesting is to have another build hook that would reply
positively as long as the target system can be emulated by QEMU.

Does that makes sense?

Thanks,
Ludo=E2=80=99.