@Colin, Sorry, I just saw this your comment 2 now. The reason I can't use mtools and grub-rescue-pc is that the grub rescue images are ISO9660 filesystem, so they're not writable.
@Colin,
Sorry, I just saw this your comment 2 now.
The reason I can't use mtools and grub-rescue-pc is that the grub rescue images are ISO9660 filesystem, so they're not writable.