[blfs-dev] Virtualization

Nathan Coulson conathan at gmail.com
Thu Feb 2 03:32:20 PST 2012

On Sun, Jan 29, 2012 at 8:20 PM, Bruce Dubbs <bruce.dubbs at gmail.com> wrote:
> I added kvm-qemu to the book.  It is a first try for virtualization and
> it took quite a bit of trial and error to get it to work.
> I've deviated a little from the rest of the book.  The 'configuration'
> section is quite long and basically describes one way to use kvm/qemu.
> We don't usually do that.  There are a couple of cases where we created
> a separate section: iptables, CA certificates, svn server, dhcp config,
> etc though.
> kvm/qemu has a *huge* number of configuration options.  Even with this
> long section of the book, we don't begin to touch most of them.
> The next thing I'm going to do is to use my old LFS system to ssh to my
> development system and run Fedora via qemu to build an svn version of
> LFS.  Whew.
> In any case, I'd appreciate feedback.  If you already have a system
> running with X, it shouldn't take a really long time -- just a moderate
> amount. :)
>   -- Bruce
> --

Not sure how much we want to broaden this, but a couple commands if
you want a speed boost

qemu-system-x86_64 --enable-kvm
  -- This allows it to use the virtualization instructions inside the
CPU.  Results in faster emulation.  Probably worth mentioning

And Paravirtualization (I think this is  out of BLFS's scope, but a
neat topic).  This allows the emulated os, to pass things like disk io
and network traffic directly to qemu, instead of qemu's emulated
hardware.  (Less CPU work, possibly faster speed)
-net nic,model=virtio -net tap
(requires VIRTIO_NET in guest kernel)
-drive file=os.img,if=virtio
(requires VIRTIO_BLK in guest kernel)

There are also other drivers, such as serial (Serial Ports), and a
baloon driver that can add/remove memory from a guest at runtime.
Perhaps even more.

[also has the paravirtualized drivers for windows here, for those that
tinker http://www.linux-kvm.org/page/WindowsGuestDrivers/Download_Drivers]

And getting to things that I don't know yet...  there is spice.  Not
entirely sure how this works, but tinkered with it once as it provided
a paravirtualized graphics system I think.  (did not work as nicely as
the normal qemu graphics system did).  Sounded like a nice system
though http://spice-space.org/

Also a flag when compiling qemu called --enable-linux-aio (Requires
http://lse.sourceforge.net/io/aio.html).    [just thought I'd mention
it, for those that know if it could be a useful optional dependancy]

Nathan Coulson (conathan)
Location: British Columbia, Canada
Timezone: PST (-8)
Webpage: http://www.nathancoulson.com

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