[QUESTION] root ext4 strange couldn't mount/can mount report

[Nick Warne <nick@ukfsn.org>]

Hi all,

kernel 2.6.28.2
Slamd64 (Slackware 64bit port).

I have been running my /home partition as ext4 for a few weeks, and it
works very well, so today I converted / root partition over too.

All works great, but I saw I was getting a funny error/no error
reported in syslog:

Jan 27 12:54:57 sauron kernel: EXT3-fs: sda2: couldn't mount because of unsupported optional features (40).
Jan 27 12:54:57 sauron kernel: VFS: Mounted root (ext4 filesystem) readonly.

i.e. root / -> /dev/sda2 couldn't mount, but it does mount, and system
boots normally and functions fine.

Reading up I found that passing rootfstype=ext4 to kernel fixes up this
warning/error, but it appears only to apply to initramfs, of which I
do not use.

Searching boot scripts, I can find no mention of ext3 mounts.

Any ideas what makes the kernel try to mount the / as ext3?  Is it a
kernel build option I missed?

Thanks,

Nick
-- 
Free Software Foundation Associate Member 5508
http://linicks.net/