Not able to debug treads using gdb 6.6 on ARM11 + linux 2.6.11 kernel

Not able to debug treads using gdb 6.6 on ARM11 + linux 2.6.11 kernel

[pankaj chauhan]

All, 

I am trying to debug a multithreaded application (written in c++) on my ARM11 board on which linux 2.6.11 kernel is running. 

I had compiled gdb to run on target platorm  (configured with: --target=arm-linux, host=arm-linux, and --build=i686-linux). When i try to attach gdb to already running thread (using "attach PID") gdb gives following error: 

------------------------
(gdb) attach 368
Attaching to process 368
warning: process 368 is a cloned process
Reading symbols from /sbin/wsccmd...done.
Using host libthread_db library "/lib/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread 1024 (LWP 356)]
Can't attach LWP 356: Unknown error 3
(gdb)
-----------------------

I do'nt understand why a new thread (PID: 356) is created, and why this unknown error is comming. please explain what may be wong here. Let me know if any more information is required. 

Please reply to chauhan_ait@yahoo.co.in also because i am not subscribed to the list yet. 

Thanks,
pankaj


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Re: Not able to debug treads using gdb 6.6 on ARM11 + linux 2.6.11 kernel

[Daniel Jacobowitz]

On Fri, Nov 02, 2007 at 10:35:39PM +0530, pankaj chauhan wrote:
> 
> I do'nt understand why a new thread (PID: 356) is created, and why this unknown error is comming. please explain what may be wong here. Let me know if any more information is required. 

It's the main thread of your process.  Try attaching to that instead.

-- 
Daniel Jacobowitz
CodeSourcery

Re: Not able to debug treads using gdb 6.6 on ARM11 + linux 2.6.11 kernel

[pankaj chauhan]

Thanks for your response daniel. 

I don't see any process with pid 356 when i do 'ps -A',  but again if i try to attach to any other thread then it says again:

----
[New Thread 1024 (LWP 356)]
Can't attach LWP 356: Unknown error 3
----

and if i try to attach to 356 it says:
----
(gdb) attach 356
Attaching to process 356
ptrace: Unknown error 3.
----

----- Original Message ----
From: Daniel Jacobowitz <drow@false.org>
To: pankaj chauhan <chauhan_ait@yahoo.co.in>
Cc: gdb@sourceware.org
Sent: Friday, 2 November, 2007 10:41:17 PM
Subject: Re: Not able to debug treads using gdb 6.6 on ARM11 + linux 2.6.11 kernel

On Fri, Nov 02, 2007 at 10:35:39PM +0530, pankaj chauhan wrote:
> 
> I do'nt understand why a new thread (PID: 356) is created, and why this unknown error is comming. please explain what may be wong here. Let me know if any more information is required. 

It's the main thread of your process.  Try attaching to that instead.

-- 
Daniel Jacobowitz
CodeSourcery


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