Re: Qemu binfmt on foreign distro

["Ludovic Courtès" <ludo@gnu.org>]

Hi,

Mathieu Othacehe <m.othacehe@gmail.com> skribis:

> On a foreign distro, one can install QEMU and setup the binfmt mechanism
> (installing binfmt-support and qemu-user-static packages on
> Ubuntu). However, without the proper --chroot-directory arguments passed
> to guix-daemon, all binaries execution relying on binfmt will throw
> ENOENT from within the guix-daemon.

Yes, so what?  :-)

Commit 7bf2a70a4ffd976d50638d3b9f2ec409763157df expects ENOEXEC in this
case, and a meaningful error message is provided when that happens.

How did you get ENOENT?  Was it because you had installed qemu/binfmt
support from the host distro, and thus /usr/bin/qemu-whatever wasn’t
found?

> So I can see two solutions here:
>
> * Remove --system argument support for guix on foreign distributions
> (except when using this argument does not require binfmt support, 32
> bits build on a 64 bits machine).
>
> * Provide some kind of script that generates the correct guix-daemon
> command line, enabling binfmt support on foreign distros.
>
> Anyhow, the current behaviour where guix build --system=... fails
> misteriously because of an ENOENT error on a foreign distro is not
> acceptable in my opinion.

How does it fail exactly, and what do you have in
/proc/sys/fs/binfmt_misc?

On Guix System, I get the expected behavior:

--8<---------------cut here---------------start------------->8---
$ sudo herd stop qemu-binfmt
Service qemu-binfmt has been stopped.
$ guix build -s aarch64-linux hello --check
La jena derivo estos konstruata:
   /gnu/store/3j4nj1y86szk6ibaqp4yc09m2p1xmkr5-hello-2.10.drv
building /gnu/store/3j4nj1y86szk6ibaqp4yc09m2p1xmkr5-hello-2.10.drv...
@ unsupported-platform /gnu/store/3j4nj1y86szk6ibaqp4yc09m2p1xmkr5-hello-2.10.drv aarch64-linux
while setting up the build environment: a `aarch64-linux' is required to build `/gnu/store/3j4nj1y86szk6ibaqp4yc09m2p1xmkr5-hello-2.10.drv', but I am a `x86_64-linux'
builder for `/gnu/store/3j4nj1y86szk6ibaqp4yc09m2p1xmkr5-hello-2.10.drv' failed with exit code 1
build of /gnu/store/3j4nj1y86szk6ibaqp4yc09m2p1xmkr5-hello-2.10.drv failed
View build log at '/var/log/guix/drvs/3j/4nj1y86szk6ibaqp4yc09m2p1xmkr5-hello-2.10.drv.bz2'.
guix build: error: build of `/gnu/store/3j4nj1y86szk6ibaqp4yc09m2p1xmkr5-hello-2.10.drv' failed
--8<---------------cut here---------------end--------------->8---

Thanks,
Ludo’.