Newer Linux kernels (2.4) allow you to add more loop devices easily by
editing /etc/modules.conf or through the use of a boot parameter.
Older kernels (2.2 ?) only had
support for 8 loop devices compiled into the kernel. In short, you were
only able to share 8 CD's on a network with this default value.
In order to support more than that default, you needed to modify the kernel source
and recompile a new kernel.
Use the following methods to determine which version of the kernel you are running.
or
Current kernels allow you to set the number of loop devices supported
without recompiling the kernel. One of these methods is to add an options
line to /etc/modules.conf.
This method will only work if your loop support
has been configured as a loadable kernel module (which is how most major
Linux distributions come preconfigured now).
Edit /etc/modules.conf and add the following line.
After making the above change, simply reboot. Or you can try to use
rmmod and insmod to make the change
on the fly - but this will not work
if you currently have any loop devices mounted (you'll get an error saying
loop: Device or resource busy).
- Note
If you do not have an /etc/modules.conf file, your module configuration
file may be called /etc/conf.modules (this name is now deprecated).
Continue with Section 3.4.
Thanks to Paul A. Sand for pointing out the /etc/modules.conf option.
If your loop support has been compiled directly into the kernel (in other words,
it is not loaded as a module), you can append the number of loop devices you would
like to support at the linux boot prompt.
Or, if you are using LILO,
you can edit your linux boot
stanza in /etc/lilo.conf and add/modify
the append= line. Here is an example stanza showing
append= (note: only add or modify the append line,
don't change your whole stanza to look like this one or your system
may not boot). For more information about LILO, consult the
LILO mini-HOWTO at
http://www.linuxdoc.org/HOWTO/mini/LILO.html.
image=/boot/vmlinuz
label=linux
root=/dev/hdb5
initrd=/boot/initrd.img
append=" max_loop=64"
vga=788
read-only
|
After changing /etc/lilo.conf, you need to run
the lilo command for your changes to take effect.
bash# lilo
Added linux *
Added linux-nonfb
Added failsafe
Added windows
Added floppy
|
Next restart your system. After your system restarts, you can check your boot command line by typing the following:
- Note
I am not sure if the loop module (compiled as a module) reads
/proc/cmdline when
the module is loaded, and therefore may not need an options line
/etc/modules.conf.
It's possible that it can (and if it doesn't, it should).
To summarize: I have not tested this.
Continue with Section 3.4.
Thanks to Tony Melia for the boot prompt info.
If you have an older kernel (v. 2.2) or if you are completely comfortable
recompiling the kernel, you can increase the number of loop devices supported by
editing the /usr/src/linux/drivers/block/loop.c file.
- Note
If you find that the kernel sources are not installed on your machine,
you'll need to consult your Linux Distribution's documentation on
how to install them (the Kernel Sources come with all distributions -
it's part of the GNU GPL licensing).
Change the number in the following line to however many loop devices
you'll need.
Compile the new kernel or module as the case may be. If you need some
help getting started with this, read /usr/src/linux/README or consult
The Linux Kernel HOWTO.
Continue with Section 3.4.
You should check how many /dev entries you have for loop devices.
The mknod command creates the devices in the
/dev directory. The loop devices have a major
number of "7", and the minor numbers begin at "0".
If your MAX_LOOP was defined as "8" in
/usr/src/linux/drivers/block/loop.c, you should have
/dev/loop0 through
/dev/loop7.
To create the /dev/loop8 device,
use the following command (subsitute the appropriate number you need for
both the "8's" in the example below).
bash# mknod -m660 /dev/loop8 b 7 8
|
Check Owner/Group & Permissions on the new file (using ls -l).
You can change the owner and group with the following command:
bash# chown root.disk /dev/loop8
|
You can change the permissions using the following command:
bash# chmod 666 /dev/loop8
|
