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Debugging multi-threaded eCos application using GDB
- To: ecos-discuss at sources dot redhat dot com
- Subject: [ECOS] Debugging multi-threaded eCos application using GDB
- From: "Stefan Syberichs" <Stefan dot Syberichs at ascom dot ch>
- Date: Fri, 3 Aug 2001 11:52:05 +0200
Hello,
We have a similar problem like Nadine:
Debugging an eCos application for the linux target is hard, because gdb is
not aware of
the eCos threads.
> We do have some ideas on how to fix this properly, basically making
> the thread-aware debugging inside gdb much more flexible, but so far
> nobody has been willing to contribute or fund any of the work
> involved.
> Bart
Bart, what exactly are the ideas for gdb ? Or does anybody have a solution
meanwhile ?
regards, Stefan
----------------------------------------------------------------------------------------------------------
To: Nadine dot Albiez-extern at ascom dot fr
Subject: Re: [ECOS] Debugging multi-threaded eCos application using GDB
From: Bart Veer <bartv at redhat dot com>
Date: Mon, 23 Apr 2001 13:52:09 +0100
Cc: ecos-discuss at sources dot redhat dot com
References: <OF8761DF62.DD359E81-ONC1256A37.00272947@ascom.fr>
Reply-To: bartv at redhat dot com
>>>>> "Nadine" == Nadine Albiez-extern <Nadine.Albiez-extern@ascom.fr>
writes:
Nadine> Hello,
Nadine> I have a question about debugging an eCos multi-threaded
Nadine> application using gdb. When I want to see the list of my
Nadine> threads , the command "info threads" returns nothing
Nadine> (gdb) info threads
Nadine> (gdb) thread 1
Nadine> Thread ID 1 not known. Use the "info threads"
command to
Nadine> see the IDs of currently known threads.
Nadine> What can I do for enabling the multi-threaded ? When I use
Nadine> a linux test application I have no problem, "info threads"
Nadine> returns the list of threads..... Is there any option when
Nadine> generating the eCos kernel to allow Gdb to see the eCos's
Nadine> Thread (cyg_thread_create)? I observe the same behavior
Nadine> with the example program "two_threaded". Is there a
Nadine> package to add to ecos.ecc? I use eCos version 1.4.8. ,
Nadine> gdb version 4.18 (I try gdb 5.0 with the same result) and
Nadine> work on a linux target .
Thread-aware debugging is not available on all targets, and
unfortunately that includes the synthetic target which I assume you
are referring to.
The problem is with the current implementation of thread-aware
debugging. It expects to be able to interact with some code inside the
embedded target, for example RedBoot or gdb stubs, that knows about
the specific thread implementation being used. Debugging the synthetic
target does not involve interacting with remote stubs, instead it uses
facilities provided by the system such as ptrace().
To confuse things further, gdb might think that you are trying to
debug a multi-threaded Linux application where the threading is
provided by Linux. This does not work either: synthetic target threads
are not built on top of Linux threads, you want the eCos semantics
rather than the Linux ones.
We do have some ideas on how to fix this properly, basically making
the thread-aware debugging inside gdb much more flexible, but so far
nobody has been willing to contribute or fund any of the work
involved.
Bart