[uml-user] UML boot question for help

[kail-gj <an_...@12...>]

Hi,


     I try to boot my uml with command ./linux ubda=../../rfs-1/root_fs mem=512m but it is failed. The boot log is 


$ ./linux ubda=../../rfs-1/root_fs mem=512m
Core dump limits :
soft - 0
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 16764928 bytes to physical memory to account for exec-shield gap
Linux version 2.6.32.8 (chipX /home/chipX/chipX/fhos/trunk/linux@suzhou-chipX) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-3) (GCC) ) #1 Fri May 13 10:46:03 CST 2016
Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 133317
Kernel command line: ubda=../../rfs-1/root_fs mem=512m root=98:0
PID hash table entries: 4096 (order: 3, 32768 bytes)
Dentry cache hash table entries: 131072 (order: 8, 1048576 bytes)
Inode-cache hash table entries: 65536 (order: 7, 524288 bytes)
Memory: 504188k available
Hierarchical RCU implementation.
NR_IRQS:15
Calibrating delay loop... 100.76 BogoMIPS (lpj=503808)
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: 8192 (order: 4, 65536 bytes)
TCP established hash table entries: 32768 (order: 7, 524288 bytes)
TCP bind hash table entries: 32768 (order: 6, 262144 bytes)
TCP: Hash tables configured (established 32768 bind 32768)
TCP reno registered
NET: Registered protocol family 1
IRQ 9/mconsole: IRQF_DISABLED is not guaranteed on shared IRQs
mconsole (version 2) initialized on /home/chipX/.uml/mq9xu4/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 985
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
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
VFS: Mounted root (ext2 filesystem) readonly on device 98:0.
IRQ 3/console-write: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 2/console: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs
Welcome to Red Hat Enterprise Linux Server
Starting udev: modprobe: FATAL: Could not load /lib/modules/2.6.32.8/modules.dep: No such file or directory


line_ioctl: tty0: unknown ioctl: 0x541e
[  OK  ]
Setting hostname localhost:  [  OK  ]
Checking filesystems
Checking all file systems.
[/sbin/fsck.ext2 (1) -- /] fsck.ext2 -a /dev/ubd/0 #### Different from your boot log
ext2fs_check_if_mount: Can't check if filesystem is mounted due to missing mtab file while determining whether /dev/ubd/0 is mounted.
fsck.ext2: No such file or directory while trying to open /dev/ubd/0
/dev/ubd/0: 
The superblock could not be read or does not describe a correct ext2
filesystem.  If the device is valid and it really contains an ext2
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 <device>


[FAILED]


*** An error occurred during the file system check.
*** Dropping you to a shell; the system will reboot
*** when you leave the shell.
/dev/fd/9: line 2: plymouth: command not found
Press enter for maintenance
(or type Control-D to continue):


Any suggestion or hint is much appreciated.


Thanks, Jotus