Comment # 23 on bug 845589 from Andrei Borzenkov

(In reply to Michael Friesenegger from comment #22)
> I know this flow is not exact.  I modified 40grub2 because it does not write
> a "result:" entry for /dev/sda3 on my system.

I know. This happens because it is called with empty subvolume and should not
attempt to strip it in this case ... at least in cases I can reproduce.

> messages.grub2.orig

Where the hell "subvol=@" comes from?

2014-10-12T09:23:24.750621-06:00 mdf-w530 linux-boot-prober: debug: btrfs:
partition=/dev/sda3, UUID=c6c44d52-7e41-4f19-8df4-55886abc2305, subvol=@

And why it is not in linux kernel path then?

Could you show btrfs subvolume list from /dev/sda3?

This entirely different from what I get with openSUSE 13.2 default install on
btrfs. I'm afraid SLE includes some patches for grub2 that deviate from both
upstream and openSUSE.