Re: KVM kernel module permission denied on foreign distro

[Giovanni Biscuolo <g@xelera.eu>]

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Hi Pierre,

Pierre Neidhardt <mail@ambrevar.xyz> writes:

> If I'm not mistaken, this is because you need to add the builders to the 'kvm'
> group.

yes! this solved the "Could not access KVM kernel module: Permission
denied" I had with "guix system vm" (both as user and root):

  $ for i in `seq -w 1 10`; do sudo usermod -G guixbuild,kvm guixbuilder$i; done
  $ sudo systemctl restart guix-daemon.service # since my init system is systemd

the fact that builds are made by a dedicated daemon using dedicated
unprivileged users (guixbuilder${i}) in an isolated environment is
pretty new to me and sometimes I forget it :-S

> From the manual ((guix) 2.4.1 Build Environment Setup):
>
> --8<---------------cut here---------------start------------->8---
> To use ‘guix system vm’ and related commands,
> you may need to add the build users to the ‘kvm’ group so they can
> access ‘/dev/kvm’, using ‘-G guixbuild,kvm’ instead of ‘-G guixbuild’
> (*note Invoking guix system::).
> --8<---------------cut here---------------end--------------->8---

I read that but skipped that because lazy people like me use installers
:-), so I used the shell installer script mentioned in "(guix)Binary
Installation" and that does not add guixbuilder${i} users to the kvm
group in "sys_create_build_user()" shell function

moreover, "(guix)Invoking guix system" should mention this in the "`vm`"
section, in case users (like me) skipped or misunderstood that part of
"(guix)Build Environment Setup" for any reason

tomorrow I'm going to propose a couple of patches to address both of the
above mentioned issues

Thanks!
Giovanni

-- 
Giovanni Biscuolo

Xelera IT Infrastructures

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