grub-update and "/usr/sbin/grub-probe: error: unknown filesystem"

Question

I've got a Debian 7 Wheezy (stable release) and my GRUB suddenly refuses to see one of my partitions. It is an OS X HFS+ partition on the GPT disk.

This behavior was introduced in the month or so and it is either caused by a routine update either of Debian or OS X. The error is /usr/sbin/grub-probe: error: unknown filesystem.

Here is a excerpt of the output:

user@wheezy:~$ sudo update-grub
Generating grub configuration file ...
Found background image: /usr/share/images/desktop-base/desktop-grub.png
Found linux image: /boot/vmlinuz-3.2.0-4-amd64
Found initrd image: /boot/initrd.img-3.2.0-4-amd64
rmdir: failed to remove `/var/lib/os-prober/mount': Device or resource busy
rmdir: failed to remove `/var/lib/os-prober/mount': Device or resource busy
rmdir: failed to remove `/var/lib/os-prober/mount': Device or resource busy
rmdir: failed to remove `/var/lib/os-prober/mount': Device or resource busy
rmdir: failed to remove `/var/lib/os-prober/mount': Device or resource busy
rmdir: failed to remove `/var/lib/os-prober/mount': Device or resource busy
rmdir: failed to remove `/var/lib/os-prober/mount': Device or resource busy
rmdir: failed to remove `/var/lib/os-prober/mount': Device or resource busy
rmdir: failed to remove `/var/lib/os-prober/mount': Device or resource busy
rmdir: failed to remove `/var/lib/os-prober/mount': Device or resource busy
grub-probe: error: unknown filesystem.
rmdir: failed to remove `/var/lib/os-prober/mount': Device or resource busy
Found Windows 8 (loader) on /dev/sda2
Found Windows 8 (loader) on /dev/sda3
Found Debian GNU/Linux (7.8) on /dev/mapper/altwheezy_vg-main_lv
/usr/sbin/grub-probe: error: unknown filesystem.
Found Debian GNU/Linux (7.8) on /dev/mapper/altwheezy_vg-main_lv_snapshot
done
user@wheezy:~$

As you can see, there is also a /usr/sbin/grub-probe: error: unknown filesystem error being printed multiple times.

I have two Debian Wheezy on the computer and I tried both of them. To no avail. I've even tried GRUB from the testing repository, but the error is still here.

I wondered if my Linux suddenly failed to see GPT HFS+ partition or its type, but it is too not the case, since I've got all the necessary packages installed (hfsplus, hfsprogs, hfsutils), gparted sees it, gdisk sees it and the filesystem type is right, but grub cannot see it.

On the OS X side, I've checked the partition from the OS X itself with Disk Utility and it didn't reported anything wrong.

Someone please direct me what should I check to determine the nature of the problem.

Answer 1

Finally I've figured it out.

It is absolutely unnecessary to have GRUB to see all of file systems. You can just instruct GRUB to bypass all operations and to chain load the next bootloader (Chameleon in my case). So I ended up with this in my /etc/grub.d/40_custom:

menuentry "OS X" --class macosx --class os {
        insmod part_gpt
        insmod hfsplus
        set root='(hd2)'
        chainloader +1
}