Re: Retrieve UUID of the partition containing prefix

[A. Wan]

When I boot a PC with GRUB2 installed I can hit 'c' to get the command
prompt.  Then I enter 'set' and I can see the value for prefix, for
example:

prefix=(hd0,msdos1)/boot/grub

Then I type 'set root=(hd0,' and hit TAB. GRUB2 shows the list of
partitions, complete with detected filesystem types and uuid, for example:

Possible partitions are:
        Partition hd0,msdos1: Filesystem type ext* ... UUID abcd...
        Partition hd0,msdos2: Filesystem type ext* ... UUID 1234...

Presumably GRUB2 can tell the UUID and filesystem type of the partition
containing the prefix (In the above example (hd0,msdos1)/boot/grub).  But
I am unable to find a way to share such information with the Linux kernel
I want to boot.

This is the use case:  My boot disk wants to mount a big filesystem image
that is always stored in the same partition as the one containing the
--boot-directory parameter when GRUB2 was installed to the boot media, but
I do not want to hard-code the UUID of the partition in the grub
configuration file every time I make another copy of the boot disk.

You may say why not search.fs_label?  But why search when GRUB2 already
know where itself is?

I appreciate any responses.  Thank you very much.

Sincerely,
Alex