[Xen-users] Overcoming loopback device limitation - revisited

["john maclean" <jayeola@xxxxxxxxx>]

Hi there chaps,

Just to get me up and running I ran `make world && make install` from
source. All went well until I started running out of loopback devices
to create guests. I know of the 8 devices limitation and I'm sure that
the loop "module" is built into the kernel;

modinfo loop
filename:       /lib/modules/2.6.16-xen/kernel/drivers/block/loop.ko
license:        GPL
alias:          block-major-7-*
vermagic:       2.6.16-xen SMP 686 gcc-3.3
depends:
parm:           max_loop:Maximum number of loop devices (1-256) (int)

OK, that number is more than enough for me. This is a laptop and I'd
want to manage about 12. So I use this boot time parameter even though
I know/think that it's a built in:-

cat /proc/cmdline
root=/dev/hda3 ro console=tty0 max_loop=32

To create some more loop back devices I ran the following:-

for X in $(seq 8 31); do mknod ;  MAKEDEV /dev/loop$X  b 7 $i ; chmod
660 /dev/loop$X; chown 0.disk /dev/loop$X;  done

Now I can only seem to have just one domU running!

#acid~#  xm list
Name                              ID Mem(MiB) VCPUs State  Time(s)
Domain-0                           0      512     1 r-----   108.4
vm01                               1       64     1 ------     0.3

acid:~# xm create vm00 -c /etc/xen/vm00
Using config file "/etc/xen/vm00".
Error: Device 769 (vbd) could not be connected. Backend device not found.

I have a few simple-ish questions that I'd a appreciate some answers for;
- What is the file system that creates loopback devices a required,
on the fly?
- How do I know if I have this?
- Did I give the newly created devices the wrong permissons?
- Why does it appear that all of the /dev/loop devices bar one are "blocked"?
- Do I have to do some /etc/udev mojo?

version:- xen-3.0.2-2
arch:- debian sarge
me:- very stuck ;)
--
John Maclean  - 07739 171 531
MSc (DIC)

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