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I have copied an ISO file into a partition (i.e. dd if=isofile of=/dev/sdb1). How can I boot into that partition via GRUB?

When I try just with chainloader (hd1,0)+1, it says unknown executable format.

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Looks like a duplicate of superuser.com/questions/154133/grub-boot-from-iso –  BloodPhilia Jun 18 '10 at 14:31
Leave this question and close the other. This one have more info. –  Nifle Jun 18 '10 at 14:46
@Nifle, I agree. –  BloodPhilia Jun 18 '10 at 14:49
No, I am asking a different thing. I have the content of the ISO file here in a partition and I asked how I can boot that partition. –  Albert Jun 18 '10 at 15:26
which version of grub? –  quack quixote Jun 18 '10 at 17:08

1 Answer 1

up vote 3 down vote accepted

See my answer on your boot-from-ISO-files question. Using that as a starting point, I ran some tests with an old hard-drive. I've previously configured Grub2 to boot a multi-ISO flash drive, so what I did was:

  1. Create a couple of partitions on an old hard drive. This was done using a USB-to-IDE adapter, so the drive appears as /dev/sdb.

    • Partition 1: FAT32, ~2GB in size
    • Partition 2: unformatted

  2. Mounted the first partition to /mnt and installed a copy of Grub from my system onto the drive:

    sudo grub-install --no-floppy --root-directory=/mnt /dev/sdb

  3. "Burned" an ISO to the second partition:

    sudo dd if=avg.iso /dev/sdb2

  4. This is an AVG virus-scanner ISO; on my multi-ISO flash drive, I use this to boot the ISO directly:

    menuentry "AVG Rescue CD" {
       loopback loop /iso/avg.iso
       linux (loop)/isolinux/vmlinuz max_loop=255 vga=791 init=linuxrc iso-scan/filename=/iso/avg.iso
       initrd (loop)/isolinux/initrd.lzm

    In order to make this work from a hard drive partition, we need to nix the loopback command and set the root device and such. My attempts to have Grub2 discover the root device automagically all failed, so I pointed it at the partition directly. This works, but watch out for Grub's device enumeration; the drive you're trying to boot from may not be (hd0). Here's a working entry for the ISO partition:

    menuentry "AVG Rescue CD" {
       linux (hd0,2)/isolinux/vmlinuz max_loop=255 vga=791 init=linuxrc
       initrd (hd0,2)/isolinux/initrd.lzm

    This results in a bootable ISO-on-partition.

This works because Grub2 can read ISO9660 filesystems, because this particular ISO is loading an OS that can cope with an ISO on a partition, and because practically everything the kernel loads is in the initrd.

If you're using Grub4DOS or Grub 1, you may be able to pull a similar trick with the chainloader. Presuming that this works to boot the Win7 ISO directly (source):

title Windows 7
  map (hd0,0)/win7.iso (hd32)
  map --hook
  chainloader (hd32)

You may have luck with this modification (assuming you "burned" the ISO to the second primary partition, (hd0,1); otherwise substitute the proper partition):

title Windows 7
  map (hd0,1) (hd32)
  map --hook
  chainloader (hd32)

You may also get away with this:

title Windows 7
  chainloader (hd0,1)

However, the ISO isn't really configured to boot from a drive, so you may run into other problems.

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