Linking a file on disk to a fake block device?

fyhuang · 10-31-2005, 06:48 AM

Hello,

Is it possible to 'attach' a file on the disk (say, an ISO image) to a fake block device (i.e. /dev/cdrom) so that programs that directly access /dev/cdrom or other will instead be redirected to that file? I tried to symlink the file to /dev/cdrom but that didn't work very well. I know there's a command somewhere to create a /dev node, but I think it requires that a 'handler' for that node already be 'registered'...

Any help with this issue would be greatly appreciated! Thanks!

mickyg · 10-31-2005, 07:19 AM

I too would be interested in this, I was trying to see if I could get GRUB to boot from an ISO image without the need to burn it to CD and one of the things I wanted to try was setting the root= in the bootloader to a block device which pointed to the ISO image to see if that worked.

kilgoretrout · 10-31-2005, 07:23 AM

You can probably do that using a loop device. For example, you can mount isos with:

# mount /<path to iso> /<mount point> -o loop

and they will read like a burned cd of the iso image file. The device file for loop is /dev/loopx where 'x' is 0 for the first loop device. In the above example you would then create a symlink to /dev/loop0 with:

# ln -s /dev/loop0 /dev/cdrom