How-to "remotely" install Slackware in a qemu VM from the host?

Didier Spaier · 07-03-2014, 07:03 AM

I want to try booting a machine to do a Slackware installation remotely, but at the moment have only one real machine (my laptop) at hand.

How can I boot a qemu VM, but from the host? Does any one know how to boot a VM from the host, through PXE or simulating a serial console, whatever? I would be grateful of any clue.

slacktroll · 07-03-2014, 07:08 AM

The easiest way would be to make a isofile from the Slackware DVD and pass it as a parameter to the guest

Didier Spaier · 07-03-2014, 07:21 AM

Quote:

Originally Posted by slacktroll

The easiest way would be to make a isofile from the Slackware DVD and pass it as a parameter to the guest

Yes, I've done that many times, but to be more clear what I really want is not use VM's console as display but a host's terminal (either in console mode or under X) as if the VM was a remote machine. I probably could figure that out from the docs + an Internet search but to be honest I feel a bit lazy today...

slacktroll · 07-03-2014, 07:31 AM

Do that, i would like to know as well

ml4711 · 07-03-2014, 08:01 AM

Is it this You need?

Code:

qemu-kvm -vnc :1 -cdrom /var/lib/kvm/TinyCore-4.7.7.iso

or You can let it PXE-boot

EDIT:
If You just start qemu, it will try to PXE-boot,
so you just have to set up the PXE-server.

and then in an other terminal window:

Code:

gvncviewer localhost:1

Richard Cranium · 07-03-2014, 08:16 AM

You can do that via libvirt and virt-manager, which isn't what you asked for.

(Even there, the cdrom/iso image has to be on same machine as the VM.)

Didier Spaier · 07-03-2014, 02:26 PM

@ ml4711: thanks!

It works well will this command:

Code:

qemu-kvm -m 2047 -vnc :1 -k fr -cdrom ~/slint.fr/testing/slint-14.1.iso -boot order=d -vga std

Amazingly, display using fbterm (as set by the installer) is right in the vnc client with a true type font (DejaVu Sans Mono as set in the installer), though fbterm be supposed to run only when controlled by an interactive tty hence not under X

I tried also without the -vga option (thus defaulting to a cirrus video card), again display is as expected (with a bitmap font is this case as fbterm is not run by the installer because there is no 32bpp vesa mode available).

So far so good, I'm going to try the other methods now.

@ Richard Cranium: thanks for the clue, I don't know libvirt and virt-manager but it never hurts to learn

Didier Spaier · 07-03-2014, 06:30 PM

Now for the PXE-boot:

At first I tried to follow PXE: Installing Slackware over the network written by Eric Hameleers.

But it failed, because as I didn't use qemu's -net option it fell back to the default "-net nic -net user". Then I willingly tried to use qemu's own network stack with this command:

Code:

qemu-kvm -m 2047 -vnc :1 -k fr -vga std -net nic -net user,tftp=/tftpboot/slint-14.1,bootfile=/pxelinux.0 -boot order=n

I lost some time figuring out needed files' layout in /tftpboot/slint.14.1 (I had to "mv isolinux/* .") but eventually that succeeded and I got the same display in the vnc client as previously.

But as that's not what I planned to do I'll try to actually use the host's PXE server tomorrow.

Didier Spaier · 07-05-2014, 05:35 AM

Now for the PXE-boot, but this time with the PXE server set in the host and IPs suggested by Eric, just added the option no_subtree_check in /etc/exports. In /etc/dhcpd.conf:

Code:

host qemu {
    hardware ethernet 52:54:00:12:34:56;
    fixed-address 192.168.0.3;
}

and the qemu command:

Code:

qemu-kvm -m 2047 -cpu host machine accel=kvm -k fr -vga std -net nic,macaddr=52:54:00:12:34:56,name=qemu -boot order=n

Slow, but it works.

Reminder: the how-to is in the installation media also, see /usb-and-pxe-installers/README_PXE.TXT

dijetlo · 07-05-2014, 05:09 PM

Take a look at virsh when you get a chance, Didier. It' a command line tool that let's you interact directly with the virtual environment through APIs in libvirt. The only other suggestions I'd make is, what your building is considered a loop or img format, you'd have a more compliant image (faster, easier to work with) if you modified it into a qcow2 format (which I think you can do via a snapshot with virsh, but I'm not on my home machine so all that documentation isn't available to me right now).
Once you have them built, you can SSH into them just like they were real machines.