[ltt-dev] LTTng 2.0 on ARM

[Mathieu Desnoyers]

* Avik Sil (avik.sil at linaro.org) wrote:
> Hi,
> 
> I'm trying to use LTTng 2.0 on a Pandaboard. After building the latest
> tools and modules I tried to run lttng and got following error:
> 
> # lttng list -k
> Spawning a session daemon
> [   55.723144] Internal error: Oops - undefined instruction: 0 [#1]
> PREEMPT SMP
> [   55.736511] Modules linked in: lttng_ftrace(+) smsc95xx
> [   55.745025] CPU: 1    Not tainted  (3.0.0-1002-linaro-omap
> #3~ppa~natty-Ubuntu)
> [   55.758697] PC is at vmalloc_sync_all+0x0/0x8
> [   55.766326] LR is at init_module+0x12/0x1c [lttng_ftrace]
> [   55.774993] pc : [<c00ef390>]    lr : [<bf8071fb>]    psr: 60000113
> [   55.774993] sp : eb9a5f50  ip : c0474c17  fp : 00000000
> [   55.793121] r10: 00000000  r9 : 00000000  r8 : c0645160
> [   55.801574] r7 : bf8071e9  r6 : 00000000  r5 : 006f2ec0  r4 : bf807424
> [   55.811370] r3 : 271aed1c  r2 : 271aed1c  r1 : bf80739a  r0 : c00ef390
> [   55.821105] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM
> Segment user
> [   55.831481] Control: 50c5387d  Table: 9984c04a  DAC: 00000015
> [   55.840454] Process modprobe (pid: 1580, stack limit = 0xeb9a42f8)
> [   55.849914] Stack: (0xeb9a5f50 to 0xeb9a6000)
> [   55.857421] 5f40:                                     eb9a4000
> c00584b7 00000000 00000001
> [   55.871765] 5f60: bf807424 bf807424 006f2ec0 bf807424 006f2ec0
> 00000000 00001a19 c005ca04
> [   55.886108] 5f80: eb9a4000 c00b1ceb 40108000 00001a19 006f2ec0
> bee9d4b4 006f2ef8 00000000
> [   55.900726] 5fa0: 00000080 c005c801 bee9d4b4 006f2ef8 40108000
> 00001a19 006f2ec0 bee9d414
> [   55.915527] 5fc0: bee9d4b4 006f2ef8 00000000 00000080 0000b979
> 006f2f04 006f2ec0 00000000
> [   55.930358] 5fe0: 00017edc bee9d418 0000aedf 401c8ae0 60000110
> 40108000 00000000 00000000
> [   55.945343] [<c00ef390>] (vmalloc_sync_all+0x0/0x8) from [<bf8071fb>]
> (init_module+0x12/0x1c [lttng_ftrace])
> [   55.962280] [<bf8071fb>] (init_module+0x12/0x1c [lttng_ftrace]) from
> [<c00584b7>] (do_one_initcall+0x6b/0xfc)
> [   55.979339] [<c00584b7>] (do_one_initcall+0x6b/0xfc) from
> [<c00b1ceb>] (sys_init_module+0x4b/0x11c)
> [   55.995544] [<c00b1ceb>] (sys_init_module+0x4b/0x11c) from
> [<c005c801>] (ret_fast_syscall+0x1/0x50)
> [   56.011932] Code: e8bdb007 bf008ff0 c06174d0 c0b83db4 (f85db500)
> [   56.028320] ---[ end trace 14e0c48d8bb29e79 ]---
> Segmentation fault
> 
> 
> After investigation I found that the oops happened while installing
> lttng-ftrace module. Any help resolving it will be appreciated. My
> kernel version is 3.0.

Hi Avik,

Can I get your kernel .config ? Also, adding a printk in lttng-modules
wrapper/vmalloc.h, just after vmalloc_sync_all_sym = (void *)
kallsyms_lookup_name("vmalloc_sync_all");

printing the vmalloc_sync_all_sym pointer value would be clearly
helpful. I would think ARM does not implement vmalloc_sync_all, so the
dummy mm/vmalloc.c vmalloc_sync_all weak symbol should be used as a
valid empty function. Please grep for vmalloc_sync_all under your
arch/arm to see if your particular omap flavor is implementing a
vmalloc_sync_all.

Thanks!

Mathieu

> 
> Regards,
> Avik
> 
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-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com