search --label not working on mmcblk

[Matthias Schoepfer]

Hi!

I have quite a funny behavior that I am not able to grasp. I am using 
grub on an "embedded" device to switch between two root file system 
partitions (A / B update schema). To set / read the partition, I use the 
grubenv. This part works as a charm.

Now I switched to eMMC as storage. I gave it a gpt partition table and 
besides a EFI parition, I have the root partition labeled rootfs1 and 
rootfs2. Since the numbers of the devices may be different when for 
example a USB drive is attached, I am using the PARTLABELs for getting 
the root device.

While

search --label rootfs1

finds the rootfs1, it does not find

search --label rootfs2

even if I give the correct hints. When I boot "manually" with 
(hd3,gpt3), everything works and the linux kernel is finding the root 
partition given as

root=PARTLABEL=rootfs2 rootwait

What can I do to debug this?!

I am using grub2 as shipped with yocto hardknott:

https://alpha.gnu.org/gnu/grub/grub-2.06~rc1.tar.xz

Modules build in: boot linux ext2 fat serial part_msdos part_gpt normal 
efi_gop iso9660 search loadenv test acpi squash4 all_video multiboot2

Any help how to tackle this is appreciated.

Regards,

   Matthias