After creating a new JFS root file system, boot (actually /etc/rc.d/rc.S ?) fails when checking it with:
/sbin/e2fsck: Bad magic number in super-block while trying to open /dev/sda7:
The superblock ...
After booting using the old ext4 root file system, using the same command as used by /etc/rc.d/rc.S:
root@CW8:~# /sbin/fsck -C -a /dev/sda7
fsck 1.41.8 (11-July-2009)
fsck.jfs version 1.1.14, 06-Apr-2009
processing started: 2/21/2010 16.10.13
Using default parameter: -p
The current device is: /dev/sda7
Block size in bytes: 4096
Filesystem size in blocks: 3662812
**Phase 0 - Replay Journal Log
Filesystem is clean.
The JFS root file system mounts OK during boot with "VFS: mounted root (jfs filesystem) readonly on device 8:7
This is happening on Slackware 13.0 32-bit with a separate ext3 /boot file system and with /usr on root.
A workaround would be to create /etc/fastboot but that's not ideal.