Hi - 
I'm encountering some strange issue with UML. I built the uml kernel from src and started them with root_fs(F14). (downloaded from http://fs.devloop.org.uk/) . Its fine for the first time. Next time(after shutdown with "init 0") ,when I start again ,somehow the file system becomes read-only and throws following error message.

Any thoughts ,how to fix this issue?
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root# ./linux ubda=Fedora14-AMD64-root_fs mem=128M eth0=tuntap,,,10.1.1.5 eth1=tuntap,,,20.1.1.6 eth2=tuntap,,,10.1.1.20
Core dump limits :
soft - NONE
hard - NONE
Checking that ptrace can change system call numbers...OK
Checking syscall emulation patch for ptrace...OK
Checking advanced syscall emulation patch for ptrace...OK
Checking for tmpfs mount on /dev/shm...OK
Checking PROT_EXEC mmap in /dev/shm/...OK
Checking for the skas3 patch in the host:
  - /proc/mm...not found: No such file or directory
  - PTRACE_FAULTINFO...not found
  - PTRACE_LDT...not found
UML running in SKAS0 mode
Adding 23814144 bytes to physical memory to account for exec-shield gap
Linux version 2.6.38.3 (root@space) (gcc version 4.4.4 20100630 (Red Hat 4.4.4-10) (GCC) ) #1 Wed Apr 20 14:52:15 IST 2011
Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 38054
Kernel command line: ubda=Fedora14-AMD64-root_fs mem=128M eth0=tuntap,,,10.1.1.5 eth1=tuntap,,,20.1.1.6 eth2=tuntap,,,10.1.1.20 root=98:0
PID hash table entries: 1024 (order: 1, 8192 bytes)
Dentry cache hash table entries: 32768 (order: 6, 262144 bytes)
Inode-cache hash table entries: 16384 (order: 5, 131072 bytes)
Memory: 123220k available
NR_IRQS:15
Calibrating delay loop... 334.23 BogoMIPS (lpj=1671168)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 256
Checking that host ptys support output SIGIO...Yes
Checking that host ptys support SIGIO on close...No, enabling workaround
Using 2.6 host AIO
NET: Registered protocol family 16
bio: create slab <bio-0> at 0
Switching to clocksource itimer
NET: Registered protocol family 2
IP route cache hash table entries: 2048 (order: 2, 16384 bytes)
TCP established hash table entries: 8192 (order: 5, 131072 bytes)
TCP bind hash table entries: 8192 (order: 4, 65536 bytes)
TCP: Hash tables configured (established 8192 bind 8192)
TCP reno registered
UDP hash table entries: 128 (order: 0, 4096 bytes)
UDP-Lite hash table entries: 128 (order: 0, 4096 bytes)
NET: Registered protocol family 1
mconsole (version 2) initialized on /root/.uml/FRi5ab/mconsole
Checking host MADV_REMOVE support...OK
VFS: Disk quotas dquot_6.5.2
Dquot-cache hash table entries: 512 (order 0, 4096 bytes)
msgmni has been set to 240
io scheduler noop registered
io scheduler deadline registered
io scheduler cfq registered (default)
TCP cubic registered
NET: Registered protocol family 17
Initialized stdio console driver
Console initialized on /dev/tty0
console [tty0] enabled
Initializing software serial port version 1
console [mc-1] enabled
 ubda: unknown partition table
Choosing a random ethernet address for device eth0
Netdevice 0 (16:40:42:14:c1:ec) : 
TUN/TAP backend - IP = 10.1.1.5
Choosing a random ethernet address for device eth1
Netdevice 1 (a2:06:ee:39:2d:08) : 
TUN/TAP backend - IP = 20.1.1.6
Choosing a random ethernet address for device eth2
Netdevice 2 (0a:80:b7:b3:d8:1b) : 
TUN/TAP backend - IP = 10.1.1.20
Switched to NOHz mode on CPU #0
EXT3-fs (ubda): error: couldn't mount because of unsupported optional features (240)
EXT2-fs (ubda): error: couldn't mount because of unsupported optional features (244)
EXT4-fs (ubda): INFO: recovery required on readonly filesystem
EXT4-fs (ubda): write access will be enabled during recovery
EXT4-fs (ubda): recovery complete
EXT4-fs (ubda): mounted filesystem with ordered data mode. Opts: (null)
VFS: Mounted root (ext4 filesystem) readonly on device 98:0.
Welcome to Fedora 
Starting udev: udevd[238]: failed to create queue file: No such file or directory

udevd[238]: error creating queue file

error sending message: Connection refused
udevadm[241]: error sending message: Connection refused

[FAILED]
Setting hostname localhost:  [  OK  ]
Checking filesystems
Checking all file systems.
[  OK  ]
Remounting root filesystem in read-write mode:  mount: can't find / in /etc/fstab or /etc/mtab
[FAILED]
mount: can't find / in /etc/fstab or /etc/mtab
Mounting local filesystems:  [  OK  ]
chmod: changing permissions of `/var/lib/random-seed': Read-only file system
rm: cannot remove `/var/run/utmp': Read-only file system
rm: cannot remove `/var/run/cron.reboot': Read-only file system
/etc/rc.d/rc.sysinit: line 593: /var/run/utmp: Read-only file system
touch: cannot touch `/var/log/wtmp': Read-only file system
touch: cannot touch `/var/log/btmp': Read-only file system
chgrp: changing group of `/var/run/utmp': Read-only file system
chgrp: changing group of `/var/log/wtmp': Read-only file system
chgrp: changing group of `/var/log/btmp': Read-only file system
chmod: changing permissions of `/var/run/utmp': Read-only file system
chmod: changing permissions of `/var/log/wtmp': Read-only file system
chmod: changing permissions of `/var/log/btmp': Read-only file system
rm: cannot remove `/tmp/.ICE-unix': Read-only file system
chown: changing ownership of `/tmp/.ICE-unix': Read-only file system
Enabling /etc/fstab swaps:  [  OK  ]
mv: cannot move `/var/log/dmesg' to `/var/log/dmesg.old': Read-only file system
/etc/rc.d/rc.sysinit: line 651: /var/log/dmesg: Read-only file system
Entering non-interactive startup
Starting auditd: [FAILED]
Starting system logger: Can't open or create /var/run/syslogd.pid.
Can't write pid.


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Cheers,
Lakshmipathi.G
FOSS Programmer.
www.giis.co.in