need help diagnosing crash/hang of EMC motion module

[Jon Elson <elson-at-pico-systems.com>]

Hello,

Thanks to Paul and others for solving the last problem I was having in
getting my parallel port motion control driver module to compile!

Now, after finding some problems in my changes to the emcmot Makefile,
I have motion modules that compile and link, but hang or crash when
they are installed.   Does anyone have some tips on debugging these?

Here is the part of the /var/log/messages file :
Jul 30 16:09:00 jeshop PAM_pwdb[474]: 1 authentication failure; (uid=0) -> root
for kde service
Jul 30 16:09:07 jeshop PAM_pwdb[474]: (kde) session opened for user root by
(uid=0)
Jul 30 16:19:52 jeshop kernel: RTLinux Extensions Loaded
(http://www.fsmlabs.com/)
Jul 30 16:19:52 jeshop kernel: mbuff: kernel shared memory driver v0.7.2 for
Linux 2.2.18-rtl3.0
Jul 30 16:19:52 jeshop kernel: mbuff: (C) Tomasz Motylewski et al., GPL
Jul 30 16:19:52 jeshop kernel: mbuff: registered as MISC device minor 254
Jul 30 19:12:12 jeshop kernel: emcmot: SHMEM_BASE_ADDRESS = 60817408
Jul 30 19:12:12 jeshop kernel: emcmot: SHMEM_KEY = 100
Jul 30 19:12:12 jeshop kernel: emcmot: PERIOD = 48000ns
Jul 30 19:12:12 jeshop kernel: emcmot: EMCMOT_TASK_PRIORITY = 2
Jul 30 19:12:12 jeshop kernel: emcmot: EMCMOT_TASK_STACK_SIZE = 8192
Jul 30 19:12:12 jeshop kernel: Unable to handle kernel NULL pointer dereference
at virtual address 0000000c
Jul 30 19:12:12 jeshop kernel: current->tss.cr3 = 00070000, %cr3 = 00070000
Jul 30 19:12:12 jeshop kernel: *pde = 00000000
Jul 30 19:12:12 jeshop kernel: Oops: 0002
Jul 30 19:12:12 jeshop kernel: CPU:    0
Jul 30 19:12:12 jeshop kernel: EIP:    0010:[<c483fdba>]
Jul 30 19:12:12 jeshop kernel: EFLAGS: 00010213
Jul 30 19:12:12 jeshop kernel: eax: 00000000   ebx: c485752c   ecx: 0000000a
edx: c4850379
Jul 30 19:12:12 jeshop kernel: esi: 00000000   edi: c14ade1c   ebp: c14ade2c
esp: c14ade28
Jul 30 19:12:12 jeshop kernel: ds: 0018   es: 0018   ss: 0018
Jul 30 19:12:12 jeshop kernel: Process insmod (pid: 17666, process nr: 35,
stackpage=c14ad000)
Jul 30 19:12:12 jeshop kernel: Stack: c4844a00 c14adf3c c483b75a c4844a00
c4835000 00000004 c481a000 00000000
Jul 30 19:12:12 jeshop kernel:        c14ade5c c4856900 00000346 0000000a
00000000 c14ade7c 00000028 00000050
Jul 30 19:12:12 jeshop kernel:        00007534 00000460 00000028 00000006
c4856000 00000000 00000346 00000018
Jul 30 19:12:12 jeshop kernel: Call Trace: [<c4844a00>] [<c483b75a>]
[<c4844a00>] [<c4835000>] [<c481a000>] [<c4856900>] [<c4856000>]
Jul 30 19:12:12 jeshop kernel:        [__generic_copy_from_user+48/64]
[__generic_copy_from_user+48/64] [<c481a6bb>] [<c4835048>] [restore_all+11/27]
[<c4836b80>] [<c481a6bb>] [<c481a6f1>]
Jul 30 19:12:12 jeshop kernel:        [__free_pages+296/308] [<c4835000>]
[<c481a000>] [<c4853598>] [<c4853598>] [sys_init_module+1111/1224] [<c4853598>]
[<c4831000>]
Jul 30 19:12:12 jeshop kernel:        [<c4835048>] [system_call+52/56]
Jul 30 19:12:12 jeshop kernel: Code: c6 40 0c 7b a1 00 d0 84 c4 89 e5 c6 40 04
09 a1 00 d0 84 c4

I'm guessing the process insmod just indicates that insmod is the last Linux
executable to touch
the module, and that insmod is really trying to tell me that my module
(univstepmod.o) has
trapped with a bad pointer - 0000000c looks like an offset was used as the full
address.
But, how do I get from this trace info back to source line number?

Also, that SHMEM_BASE_ADDRESS looks suspicious.

Thanks much in advance!

Jon