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Re: debugging threads on 64bit GNU/Linux with 32bit debugger?
- From: Daniel Jacobowitz <drow at false dot org>
- To: Joel Brobecker <brobecker at adacore dot com>
- Cc: gdb at sourceware dot org
- Date: Wed, 15 Aug 2007 15:43:39 -0400
- Subject: Re: debugging threads on 64bit GNU/Linux with 32bit debugger?
- References: <20070815193649.GH24369@adacore.com>
On Wed, Aug 15, 2007 at 12:36:49PM -0700, Joel Brobecker wrote:
> Here is the situation: We're using a gcc/gdb toolset built on a 32bit
> x86-linux machine. We're using this toolset on a 64bit machine running
> a 64bit GNU/Linux machine. The resulting executable is runing in 32bit
> compatibility mode.
>
> Everything seems to be working fine, except that we're having trouble
> debugging threaded apps. The thread library used is the NPTL, and the
> debugger is reporting to use what seems to be the correct (32bit)
> instance of the libthread_db library (the 32bit version in /lib/tls,
> not the one in /lib64/tls).
>
> The debugger fails at startup time saying:
>
> [Thread debugging using libthread_db enabled]
> Cannot find new threads: generic error
The answer is that you need a bunch of kernel patches for this to
work. You may want to try a very current kernel; I don't know when
the patches were applied, but I believe they have been at this point.
It was probably some point between 2.6.17 and 2.6.22.
--
Daniel Jacobowitz
CodeSourcery