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I found it very strange, but common configuration I have found in Internet does not really work for me.

  1. I have downloaded Ubuntu ISO and Debian Live CD.
  2. I have created Grub4DOS USB and copied these ISO images to USB.
  3. Grub configuration is:

.

title Ubuntu Live CD
set image=/ubuntu-12.10-desktop-i386.iso
find --set-root %image%
map %image% (0xff) || map --mem %image% (0xff)
map --hook
chainloader (0xff)

title Debian Live CD
set image=/debian-live-6.0.6-i386-rescue.iso
find --set-root %image%
map %image% (0xff) || map --mem %image% (0xff)
map --hook
chainloader (0xff)

Now the problem is: for both distros kernel is loaded OK, but it cannot find and mount root FS and ends in a loop trying to mount it.

Why it goes wrong? What is the working configuration?

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3 Answers

Booting ISOs from USBs with Grub4Dos is often a trial-and-error process. The below was not tested, but it's something to try:

title Ubuntu 12.10
find --set-root /ubuntu-12.10-desktop-i386.iso
map /ubuntu-12.10-desktop-i386.iso (0xff) || map --mem /ubuntu-12.10-desktop-i386.iso (0xff)
map --hook
root (0xff)
kernel /casper/vmlinuz boot=casper iso-scan/filename=/ubuntu-12.10-desktop-i386.iso quiet splash --
initrd /casper/initrd.lz

If the above works, use a similar configuration for the Debian Live CD

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Why is this "something to try"? It would improve your answer if you explain the reasoning behind the snippet, and especially the reasoning behind the differences between it and what the OP has already tried. –  Michael Kjörling Apr 3 '13 at 14:23
    
How is it possible to load ISO image to memory and boot from that ISO (i.e. I want to see and to choose from ISO menu)? Otherwise I need to copy all variations of configuration from live disks to my config. –  dma_k Apr 8 '13 at 23:12
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See http://rmprepusb.blogspot.co.uk/2013/09/why-is-it-so-difficult-to-boot-iso.html for an explanation. P.S. Easy2Boot will boot 99% of all linux LiveCDs in the world just by copying the ISOs to your USB drive. You can even boot from multiple linux ISOs all with their own persistence!

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Sorry, this should really be a comment but not an answer, however I am not allowed to comment yet. So :

Have you tried editing this line:

map %image% (0xff) || map --mem %image% (0xff)

,removing map %image% (0xff) and leaving just map --mem %image% (0xff)

or at least swapping them around?

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