How important is the MBR partition offset of grub-mkrescue ?

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

i stumbled over a problem in the handling of grub-mkrescue
images on USB stick by Linux in /dev/disk/by-label.

The first MBR partition begins at 512-LBA 1 and thus is
not mountable as ISO image. I understand this is intentional.

ISO filesystems have a label (Volume Id) which gets used
for auto-mounting and shows up in modern Linuxes as
symbolic link in directory /dev/disk/by-label. 

But Linux (or its udev) insists in linking to /dev/sdX1
rather than to /dev/sdX, where the ISO filesystem is
mountable.
So this link cannot be used for mounting the ISO.

I hate automounters, but /dev/disk/by-label is also
a good way for a booting system to find its own
filesystem from where it stems.

----------------------------------------------------------

Is a workaround known on Linux side ? (E.g. is it a known
bug in udev configurations which can be fixed ?)

How important ist the partition start at LBA 1 in comparison
to this obvious drawback of grub-mkrescue images on Linux ?
(Start at LBA 0 solves the problem but makes the MBR part
of the first partition. I understand this is undesirable
somehow.)

Actually i wanted to show a system packager how to
use ./by-label instead of test-mounting all files in
/proc/partitions. Are there other methods which one
could use in the Linux initial RAM disk to find the
USB stick from where GRUB2 did boot ?


Have a nice day :)

Thomas