Package: grub-common Version: 2.02~beta2-22+deb8u1 Steps to reproduce: -------------
1. Hard drive (EFI mode) has Btrfs "/" partitions of two Debian-derived Linux OSes: /dev/sda2 Xubuntu 13.04 with GRUB package version 2.00-13ubuntu3 - Hereinafter, "Ubuntu" refers to this _specific_ install and *NOT* to Ubuntu OSes generally. /dev/sda3 Linux Mint Debian Edition 2 "Betsy" with GRUB package version as noted in "Version" pseudo-header of this bug report (from Debian Jessie) - Hereinafter known as "LMDE". The Ubuntu install is in subvolume "@" of the Btrfs filesystem. I believe this partition was installed by a vendor who sells a lot of Linux PCs, and/or using subvolume "@" was recommended at one time as a best practice (although I wasn't able to find it on the Web recently), so a high percentage of Btrfs users is likely to be using subvolume "@" like this. 2. Run "update-grub" in LMDE. 3. Reboot the PC and select Ubuntu option from GRUB menu. 4. GRUB is unable to boot Linux, and halts with an error message that's something like the following: Unable to find /boot/vmlinuz-3.blah.blah alloc magic is broken at 0xXXXXXXXX (0xXXXXXXXX). Aborted. Press any key If I alter the folders in the EFI system partition so that Ubuntu's .efi file (instead of LMDE's) is the one that boots, then the Ubuntu-generated GRUB menu can successfully boot either Ubuntu or LMDE. Comments on possible fix: ------------- In /boot/grub/grub.cfg in the 2 OS installs, I compared the section that boots Ubuntu. The Ubuntu grub.cfg (section made by the /etc/grub.d/linux script) contains 3 things that are missing from the LMDE grub.cfg (section made by the /etc/grub.d/os-prober script): * The filename parameter to the "linux" and "initrd" commands has a /@ prefix (i.e., it looks like /@/boot/vmlinuz...) * After the "root=" partition spec, there is "rootflags=subvol=@" * Finally, there are kernel command-line parameters (e.g., "quiet splash") - not relevant to the boot failure, but probably should still be fixed. Manually updating LMDE's grub.cfg with these differences causes Ubuntu to boot successfully when the LMDE-generated "Ubuntu" GRUB menu option is chosen. I know that grub.cfg isn't normally supposed to be updated manually; I did this for troubleshooting only. I stated the Ubuntu GRUB package version only to document that the /etc/grub.d/linux script in that GRUB version seems to have correct logic that maybe can be ported to /etc/grub.d/os-prober in the current GRUB version. Specifically, there appears to be a function called "make_system_path_relative_to_its_root" which seems to detect that /boot/vmlinuz is really at /@/boot/vmlinuz. Thanks in advance for reviewing this. -dg1727
