Hi All,
 I am trying to port the click modular router to a 3.4 kernel and run it under UML. I got the patch to compile for a 3.4 kernel under the UML architecture, however when I boot up the UM kernel the process simply hangs without every making a call to "start_kernel". To try and get some debug info I ran it under gdb, and after interrupting the hung UM linux, I got the following backtrace:
asridharan§avi-server ß/dev/click-port/click-linux-3.0/src $ gdb ./linux
GNU gdb (Gentoo 7.2 p1) 7.2
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Reading symbols from /home/asridharan/dev/click-port/click-linux-3.0/src/linux...done.
(gdb) b start_kernel
Breakpoint 1 at 0x6000152e: file init/main.c, line 466.
(gdb) r
Starting program: /home/asridharan/dev/click-port/click-linux-3.0/src/linux
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
Program received signal SIGINT, Interrupt.
0x0000000060028d60 in __delay (loops=410) at arch/x86/um/delay.c:17
17        asm volatile(
(gdb) bt
#0  0x0000000060028d60 in __delay (loops=410) at arch/x86/um/delay.c:17
#1  0x0000000060028d99 in __const_udelay (xloops=<value optimized out>)
    at arch/x86/um/delay.c:46
#2  0x000000006025a205 in panic (fmt=<value optimized out>)
    at kernel/panic.c:174
#3  0x000000006000aad2 in mark_bootmem (start=2049, end=8192,
    reserve=<value optimized out>, flags=0) at mm/bootmem.c:351
#4  0x000000006000b512 in free_bootmem (addr=<value optimized out>,
    size=<value optimized out>) at mm/bootmem.c:395
#5  0x0000000060002b5c in setup_physmem (start=<value optimized out>,
    reserve_end=<value optimized out>, len=33554432,
    highmem=<value optimized out>) at arch/um/kernel/physmem.c:108
#6  0x00000000600031f5 in linux_main (argc=1, argv=0x7fffffffe0a8)
    at arch/um/kernel/um_arch.c:345
#7  0x0000000060003a97 in main (argc=1, argv=0x7fffffffe0a8,
    envp=<value optimized out>) at arch/um/os-Linux/main.c:152
(gdb) frame 2
#2  0x000000006025a205 in panic (fmt=<value optimized out>)
    at kernel/panic.c:174
174            mdelay(PANIC_TIMER_STEP);
(gdb) list
169            touch_softlockup_watchdog();
170            if (i >= i_next) ä
171                i += panic_blink(state ^= 1);
172                i_next = i + 3600 / PANIC_BLINK_SPD;
173            ¨
174            mdelay(PANIC_TIMER_STEP);
175        ¨
176    ¨
178    EXPORT_SYMBOL(panic);
(gdb) quit
A debugging session is active.

    Inferior 1 Äprocess 15622Ü will be killed.

Quit anyway? (y or n) y

I definitely have not modified any UM specific files, so the behavior is a bit confusing. I can understand if the kernel crashes after bootup, since I have modified some code in the network stack. However, this did not make much sense to me.

Would be grateful to gain some insights into the problem.