[efi boot to unexpected media] plug in live usb and DVD at the same time, try to boot from DVD but it comes to usb

I think this behavior is raised by the grub search command in memdisk:

1. in the reproducing step 8, press e and then press F2 to make ourselves to be dropped into the grub shell
2. cat (memdisk)/grub.cfg, shows
   grub shell> cat (memdisk)/grub.cfg
   if ! search --file --set=root /.disk/info: then
        search --file --set=root /.disk/minu-info
   fi
   set prefix=($root)/boot/grub
   if [ -e $prefix/x86_64-efi/grub.cfg ]; then
        source $prefix/x86_64-efi/grub.cfg
   else
        source $prefix/grub.cfg
   fi

3. investigate the search behavior,
it seems that grub iterates hd before cd always.

grub-core/disk/efi/efidisk.c

static int
grub_efidisk_iterate (int (*hook) (const char *name))
{
  struct grub_efidisk_data *d;
  char buf[16];
  int count;

  for (d = fd_devices, count = 0; d; d = d->next, count++)
    {
      grub_snprintf (buf, sizeof (buf), "fd%d", count);
      grub_dprintf ("efidisk", "iterating %s\n", buf);
      if (hook (buf))
>.......return 1;
    }

  for (d = hd_devices, count = 0; d; d = d->next, count++)
    {
      grub_snprintf (buf, sizeof (buf), "hd%d", count);
      grub_dprintf ("efidisk", "iterating %s\n", buf);
      if (hook (buf))
>.......return 1;
    }

  for (d = cd_devices, count = 0; d; d = d->next, count++)
    {
      grub_snprintf (buf, sizeof (buf), "cd%d", count);
      grub_dprintf ("efidisk", "iterating %s\n", buf);
      if (hook (buf))
>.......return 1;
    }

  return 0;
}

4. usb will be regarded as hd device, so the search command always set the variable root as usb (more precisely, any other hard disk devices with .disk/info) instead of our selection, DVD

is there any way to parse the bios information about "where the grub efi application is loaded" to grub instead of using the search command??

Private bug which affects Ubuntu-recovery : bug #1185375

This isn't really a bug. Given two identical install images on different media, the system can't figure out which one you intended to use. Instead of giving it both, just give it the one you intend to use.

@Phillip,
This actually affects users when there is a partition on hard driver with install image (for recovery use for example). If deleting this partition is not an option, user can never boot into CDROM.
I think it will be great if efi grub application can be able to know which partition/media it is on (maybe from BIOS information) and find the grub.cfg on the same partition to avoid doing search.

From your initial description it sounded like you were talking about having the exact same image in both places. If that is the case, then there is no telling them apart, and which is used doesn't really matter. If you are talking about say, an old release on the recovery partition and a new release in the dvd, that would be something different.

@Phillip,

Sorry, the original description might be a little bit misleading. Yes, we were taling about "an old release on the recovery partition and a new release in the dvd". What we found is, user can never boot into the new release in the dvd.