Guide to running Windows under the qemu emulator

zero79 · 11-10-2005, 07:50 PM

wow, good deal -- a virtual os for only $7.50.

i am amazed that you were able to get the printer to work in qemu. goes to show that it is a quality piece of software.

peace.

wilsonsamm · 09-04-2007, 03:38 PM

Hello there.
First of all, let me congratulate you on an excellent guide. Methinks this should be linked to from the qemu site, so people like me don't end up finding it thrô the google

I have a slight problem. Well it's not really a problem, it's more like an inconvenience: the inconvenience is that whenever I type the following
$qemu -cdrom ubuntu-7.04-desktop-desktop-i386.iso -hda ubuntu.img -boot d -k no
(ok, I didn't quite follow your guide because I don't have a windows disc

) I get the following message:
Could not configure /dev/rtc to have a 1024Hz timer. This isn't a fatal error, but for better emulation accuracy either use a 2.6 or type "echo 1024 > /proc/sys/dev/rtc/max-user-freq" as root.
»(I have a 2.6.21.5-smp kernel, btw)«
You don't have enough space in /dev/shm for the 128MB of QEMU virtual RAM. To have more space available provided you have enough RAM and swap, do as root
umount /dev/shm
mount -t tmpfs -o size=144m none /dev/shm
or disable the accelerator module with -no-kqemu
$

And since I suspect it's relevant, I post here my fstab:

Code:

/dev/hda3	swap		swap	defaults			 0 0
/dev/hda1	/		ext3	defaults			 1 1
/dev/hda4	/home		reiserfs defaults			 1 2
/dev/hda2	/mnt/winxp	vfat	rw,user,loop,noauto,offset=32256 0 0
none		/dev/shm	tmpfs	defaults			 0 0
/dev/sda1	/mnt/widget	vfat	defaults			 1 0
/dev/cdrom	/mnt/cdrom	auto	noauto,users,ro			 0 0
/dev/fd0	/mnt/floppy	auto	noauto,users			 0 0
devpts		/dev/pts	devpts	gid=5,mode=620			 0 0
proc		/proc		proc	defaults			 0 0

So could anyone suggest some more suitable values to go in here, if indeed that's what to do, please?
RESOLUTION of the »INCONVENIENCE«.
change that /dev/shm line up there to the following:
none /dev/shm tmpfs size=128M 0 0
I never knew about the "size=" function

wilsonsamm · 09-04-2007, 03:44 PM

Also, the kqemu module seems not to be activated. It seems so because qemu tells me so:
Could not open /dev/kqemu - QEMU acceleration layer not activated.
And the emulation is quite slow.

I have done »modprobe kqemu« and rebooted, but this message keeps coming back. Installation of an operating system on a virtual machine takes one year to complete.

johnhamiltion · 09-05-2007, 08:37 AM

Quote:

Originally Posted by wilsonsamm

I have a slight problem.

The tmpfs size is usually set to half the size of your RAM.

You can see the size of the tmpfs with the df command.

You can reset the size in one of the boot scripts in /etc/init.d/ (you will have to search around) or

you can restrict the amount of ram that qemu uses to megs = (1/2 x RAM) - 1 with the -m option, ie,

qemu -m megs -cdrom ..... etc

wilsonsamm · 09-14-2007, 06:13 PM

Thanks, John Hamiltion.

Quote:

Originally Posted by wilsonsamm

Also, the kqemu module seems not to be activated. It seems so because qemu tells me so:
Could not open /dev/kqemu - QEMU acceleration layer not activated.
And the emulation is quite slow.

I have done »modprobe kqemu« and rebooted, but this message keeps coming back. Installation of an operating system on a virtual machine takes one year to complete.

Further research into this problem on my particular system: dmesg | less reveals kqemu to be activated. I recompiled qemu, when ./configure confirmed that kqemu was indeed activated.
"Aha", I thôt, "qemu can't open /dev/kqemu. Maybe it's a permission fault!"
But, alas, even running qemu with root permissions doesn't help. OK, so it doesn't report an error trying to open the device node, but no speed improvements either.

Anyone know what the problem could be?

acummings · 11-22-2008, 12:03 AM

Quote:

dmesg | less reveals kqemu to be activated.

Yes. kqemu kernel module is loaded.

I've never tried to run Qemu as root

Quote:

Anyone know what the problem could be?

FWIW I just now my 2nd Qemu (on a 2nd, a later computer with Slackware 12.1) which could not open /dev/kqemu

whereas my older machine with Slackware 12.0 with Qemu did not have the /dev/kqemu problem

/dev/kqemu file permissions for the o (other) are rw on old machine

on same file of new machine there are no o permissions there are only permissions for u and for g

(as root) chmod o+rw

made it work. I manually load kqemu the next root owned /usr/local/bin/kqemu_do file is in my path is executable

I have a sudo entry for my user for /usr/local/bin/kqemu_do

note the chmod o+rw

But do not do this because I so far did it (someone may write something terrible onto me)

security security security

As soon as I get the **secure** way to do this, my old way is discarded.

Code:

#!/bin/sh
# kqemu accelerator
#
#

kqemu_start() {
  # If kqemu module is not loaded, load it:
      echo "Loading Kqemu accelerator:  /sbin/modprobe kqemu"
      /sbin/modprobe kqemu
#      echo 1024 > /proc/sys/dev/rtc/max-user-freq
      sleep 1
      chmod o+rw /dev/kqemu
}

kqemu_stop() {
      echo "Unloading Kqemu accelerator:  /sbin/modprobe -r kqemu"
      /sbin/modprobe -r kqemu
}


case "$1" in
'start')
  kqemu_start
  ;;
'stop')
  kqemu_stop
  ;;
*)
  echo "usage $0 start|stop"
esac

Alan.