bug#22633: Provide a kvm-less qemu / guix system vm

[Christopher Allan Webber]

Ludovic Courtès writes:

> Jookia <address@hidden> skribis:
>
>> We should probably also blacklist kvm on Libreboot machines too somehow,
>
> A simple way to achieve this is with:
>
>   (operating-system
>     ;; …
>     (kernel-arguments '("modprobe.blacklist=kvm-intel,kvm")))

I tried this:

  (operating-system
    (kernel linux-libre-4.1)
    (kernel-arguments '("modprobe.blacklist=kvm-intel,kvm"))
    ...)

The generated Grub configuration looks right:

  menuentry "GNU with Linux-Libre 4.1.17 (alpha)" {
    search --label --set guix
    linux 
/gnu/store/k3l4g22vypwniy0k3f8xha9l8p1s716d-linux-libre-4.1.17/bzImage 
--root=guix --system=/gnu/store/flq2702dmj6ppqc4iix6xgp0q364yl3l-system 
--load=/gnu/store/flq2702dmj6ppqc4iix6xgp0q364yl3l-system/boot 
modprobe.blacklist=kvm-intel,kvm
    initrd /gnu/store/flq2702dmj6ppqc4iix6xgp0q364yl3l-system/initrd
  }

Unfortunately, after rebooting into it:

  address@hidden:~$ lsmod | grep kvm
  kvm_intel             155648  0
  kvm                   491520  1 kvm_intel
  address@hidden:~$ ls /dev/kvm
  /dev/kvm

Not sure why it didn't seem to do anything...

> But I guess ‘guix system vm’ will now fail.
>
> We could change the two occurrences of ‘-enable-kvm’ to use this flag if
> and only if /dev/kvm exists (I think it doesn’t exist when the kvm
> modules are not loaded.)

If we could really get kvm blocked, I could write this patch.

> Thoughts?
>
> Ludo’.