Re: Reliable way to run emulated Linux under NetBSD

[Gerard Lally <lists+netbsd.users%netmail.ie@localhost>]

At date and time Thu, 14 Aug 2014 19:16:15 +0200, Kamil Rytarowski wrote:

> Hello,
> 
> So nobody actually uses qemu?
> I will give a try to XEN.
> 
> Thanks,

I think Xen is a better choice myself. I tested it a couple of years
ago and found it stable and fast. I had the following domUs running
under a NetBSD dom0:

NetBSD (x3) -- paravirtualised
Slackware (x1) -- paravirtualised
Windows 2008 (x1) -- HVM
Windows XP (x1) -- HVM

The Slackware domU was very interesting. I'll try to explain from
memory, but it's been a while so I don't have all the details. I do have
notes but they're not accessible to me right now. If you get stuck i'll
dig them out and see if they help.

What I did was to install NetBSD first, using just 5 or 10 GB of the
disk, and then set up Xen. I then installed Slackware on the remainder
of the disk, making sure to install Lilo to /boot, not MBR. I installed
Slackware on Logical Volumes (LVM) - lvm-root, lvm-home, etc. I compiled
a new kernel and initrd in Slackware with Xen support (leaving out all
hardware and other options not relevant to a Xen domU), and I copied
this kernel and the initrd to NetBSD's / . I did not delete the old
kernel, but left it as the first option for Lilo. I aslo configured the
NetBSD bootloader to boot into Slackware, using the fdisk -b option.

I then made sure to configure /etc/fstab in Slackware with blkid
references, to ensure Slackware would be able to boot as a domU and as
a physical machine. Another thing I did was to set up Slackware with a
VNC server and also XDMCP. I also set up NFS to share files between the
dom0 and domU.

After all this I was able to return to NetBSD and configure a domU for
Slackware, running in paravirtualised mode (PV is lightning fast). To
access the Slackware domU from the dom0 I used either VNC or XDMCP.
Both of these were fast; the only thing I couldn't configure at the time
was audio. But the icing on the cake for me was also being able to boot
into the same Slackware as a physical machine, by using the first kernel.
So I had a physical Linux setup dual-booting with NetBSD which also
served as a domU inside NetBSD's Xen! To my mind this was incredible.

I fully intend to replicate this setup as my day-to-day working setup
when NetBSD 7 is released. I've learnt a lot about NetBSD since that I
didn't know then. I recommend NetBSD Xen highly: you have all the
benefits of NetBSD and with a paravirtualised Linux domU you also have
the benefit of a very fast Linux setup. And if you do what I did, you
can also dual-boot into this Linux setup whenver you want, if there is
something you find you can't do while it is running under Xen as a domU.

Hope this helps.

-- 
Gerard Lally