Hi

I want to use UML on my FC6 ( kernel 2.6.18-1.2798.fc6-i686 ) system. I have 256 MB RAM.

I get the following output when i try running UML

[root@localhost uml]# ./uml_linux usd0=root_fs
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
- PTRACE_FAULTINFO...not found
- PTRACE_LDT...not found
UML running in SKAS0 mode
Adding 13041664 bytes to physical memory to account for exec-shield gap
Checking that ptrace can change system call numbers...OK
Checking syscall emulation patch for ptrace...OK
Checking advanced syscall emulation patch for ptrace...OK
[42949372.960000] Linux version 2.6.18 (root@mamba) (gcc version 4.1.1 (Gentoo 4.1.1)) #2 Wed Sep 20 20:13:42 BST 2006
[42949372.960000] Built 1 zonelists. Total pages: 11376
[42949372.960000] Kernel command line: usd0=root_fs root=98:0
[42949372.960000] PID hash table entries: 256 (order: 8, 1024 bytes)
[42949372.960000] Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
[42949372.960000] Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
[42949372.960000] Memory: 28620k available
[42949373.270000] Security Framework v1.0.0 initialized
[42949373.270000] SELinux: Disabled at boot.
[42949373.270000] Capability LSM initialized
[42949373.270000] Mount-cache hash table entries: 512
[42949373.270000] Checking for host processor cmov support...Yes
[42949373.270000] Checking for host processor xmm support...No
[42949373.270000] Checking that host ptys support output SIGIO...Yes
[42949373.270000] Checking that host ptys support SIGIO on close...No, enabling workaround
[42949373.270000] Using 2.6 host AIO
[42949373.270000] NET: Registered protocol family 16
[42949373.270000] NET: Registered protocol family 2
[42949373.560000] IP route cache hash table entries: 512 (order: -1, 2048 bytes)
[42949373.560000] TCP established hash table entries: 2048 (order: 1, 8192 bytes)
[42949373.560000] TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
[42949373.560000] TCP: Hash tables configured (established 2048 bind 1024)
[42949373.560000] TCP reno registered
[42949373.560000] Checking host MADV_REMOVE support...MADV_REMOVE failed, err = -22
[42949373.560000] Can't release memory to the host - memory hotplug won't be supported
[42949373.560000] mconsole (version 2) initialized on /root/.uml/QPAk9D/mconsole
[42949373.560000] ubd: Synchronous mode
[42949373.560000] Host TLS support detected
[42949373.560000] Detected host type: i386
[42949373.560000] audit: initializing netlink socket (disabled)
[42949373.560000] audit(1201970580.991:1): initialized
[42949373.560000] VFS: Disk quotas dquot_6.5.1
[42949373.560000] Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[42949373.560000] fuse init (API version 7.7)
[42949373.560000] Initializing Cryptographic API
[42949373.560000] io scheduler noop registered
[42949373.560000] io scheduler anticipatory registered (default)
[42949373.560000] io scheduler deadline registered
[42949373.560000] io scheduler cfq registered
[42949374.280000] loop: loaded (max 8 devices)
[42949374.280000] nbd: registered device at major 43
[42949374.280000] PPP generic driver version 2.4.2
[42949374.280000] SLIP: version 0.8.4-NET3.019-NEWTTY (dynamic channels, max=256).
[42949374.280000] tun: Universal TUN/TAP device driver, 1.6
[42949374.280000] tun: (C) 1999-2004 Max Krasnyansky <maxk@qualcomm.com>
[42949374.280000] Netfilter messages via NETLINK v0.30.
[42949374.280000] ip_conntrack version 2.4 (223 buckets, 1784 max) - 228 bytes per conntrack
[42949374.930000] ctnetlink v0.90: registering with nfnetlink.
[42949374.930000] ip_conntrack_pptp version 3.1 loaded
[42949374.930000] ip_nat_pptp version 3.0 loaded
[42949374.930000] ip_tables: (C) 2000-2006 Netfilter Core Team
[42949375.670000] ClusterIP Version 0.8 loaded successfully
[42949375.670000] arp_tables: (C) 2002 David S. Miller
[42949375.780000] TCP bic registered
[42949375.780000] NET: Registered protocol family 1
[42949375.780000] NET: Registered protocol family 10
[42949375.780000] lo: Disabled Privacy Extensions
[42949375.780000] IPv6 over IPv4 tunneling driver
[42949375.780000] ip6_tables: (C) 2000-2006 Netfilter Core Team
[42949376.200000] NET: Registered protocol family 17
[42949376.270000] CCID: Registered CCID 3 (ccid3)
[42949376.270000] CCID: Registered CCID 2 (ccid2)
[42949376.270000] Initialized stdio console driver
[42949376.270000] Console initialized on /dev/tty0
[42949376.270000] Initializing software serial port version 1
[42949376.350000] ubda: unknown partition table
[42949376.540000] kjournald starting. Commit interval 5 seconds
[42949376.540000] EXT3-fs: mounted filesystem with ordered data mode.
[42949376.540000] VFS: Mounted root (ext3 filesystem) readonly.

The terminal simply hangs after this and i have to kill uml_linux .

I checked the homesite. It said to disable CONFIG_COMPAT_VDSO.

I did so by changing the parameter

CONFIG_COMPAT_VDSO=n

in /usr/src/kernels/2.6.18-1.2798.fc6-i686/.config file

Even after doing this change and rebooting by system, I faced the same problem. Also when i changed the parameter vdso by this--

[root@localhost uml]#echo 0 > /proc/sys/kernel/vdso

and checked by running UML again, still i got the same problem. The terminal simple hangs after, "VFS: Mounted root (ext3 filesystem) readonly."

Does anyone has ever faced a similar situation, or knows what to do in this situation please help me out.

Abhijeet