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The ext2 (and ext3, ext4) filesystems write the number of free inodes to location 0x410. On a MINIX filesystem, that same location is used for the MINIX superblock magic number. If the number of free inodes on an ext2 filesystem is equal to any of the four MINIX superblock magic values plus any multiple of 65536, GRUB's MINIX filesystem code will probe it as a MINIX filesystem. In the case of an OS using ext2 as the root filesystem, since there will ordinarily be some amount of file creation and deletion on every bootup, it effectively means that this situation has a 1:16384 chance of being hit on every reboot. This will cause GRUB's filesystem probing code to mistakenly identify an ext2 filesystem as MINIX. This can be seen by e.g. "search --label" incorrectly indicating that no such ext2 partition with matching label exists, whereas in fact it does. After spotting the rough cause of the issue I was facing here, I borrowed much of the diagnosis/explanation from meierfra who found and investigated the same issue in util-linux in 2010: https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/518582 This was fixed in util-linux by having the MINIX code check for the ext2 magic. Do the same here. Signed-off-by: Daniel Drake <drake@endlessm.com> Reviewed-by: Derek Foreman <derek@endlessos.org> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This is GRUB 2, the second version of the GRand Unified Bootloader. GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more robust, more powerful, and more portable. See the file NEWS for a description of recent changes to GRUB 2. See the file INSTALL for instructions on how to build and install the GRUB 2 data and program files. Please visit the official web page of GRUB 2, for more information. The URL is <http://www.gnu.org/software/grub/grub.html>. More extensive documentation is available in the Info manual, accessible using 'info grub' after building and installing GRUB 2. There are a number of important user-visible differences from the first version of GRUB, now known as GRUB Legacy. For a summary, please see: info grub Introduction 'Changes from GRUB Legacy'