Re: qemu instructions for manual

[ludo@gnu.org (Ludovic Courtès)]

Leo Famulari <leo@famulari.name> skribis:

> This appears to be the minimum QEMU invocation that works:
> $ qemu-system-x86_64 \
> -net user \
> -net nic,model=virtio \
> -m 256 \
> ./qemu-image

In practice -enable-kvm is highly recommended too.  I think anything
less than 5 to 8(?) years old supports virtualization extensions.

> Annotated version:
> # System type to emulate. Does this have to match the host hardware? Can
> # "foreign" arch machine images be built with Guix?
> $ qemu-system-x86_64 \

In theory we should be able to cross-compile complete GuixSD images to
other architectures, but that’s never been tried and there are probably
lots of build issues on the way, so let’s say that this has to match the
hardware platform or a sibling thereof (e.g., i686 code can be built on
x86_64.)

> # Unprivileged user mode networking. Guest can access host but not vice versa.
> # If you don't choose a network stack, the boot process will fail.
> -net user \
>
> # You must create a network interface of a given model. You can get a list of
> # available NIC types by running `qemu-system-$arch -net nic,model=help`. If
> # you don't create a NIC, the boot process will fail.
> -net nic,model=virtio \
>
> # RAM available to the guest OS. Defaults to 128 megabytes, which is not enough
> # for the Guix daemon. More is better.
> -m 256 \
>
> OPTIONAL: If your system is x86 with hardware virtualization extensions,
> enabling the kernel virtual machine will make things go much faster.
> -enable-kvm \
>
> # Path to the virtual machine image
> ./qemu-image

Sounds good!

Note that our QEMU package installs two Info manuals.  They are sparse,
but helpful.

In the Guix manual, and interesting thing would be an “Installating
GuixSD in a VM” section.  This is a bit more involved than the above,
because you need a target disk image separate from the installation
image, but the above is a good start.

Thanks,
Ludo’.