Re: 2.6.19-rc6-mm2 hangs when gdb is run on a multithread program

[walt <w41ter@gmail.com>]

Jeremy Fitzhardinge wrote:
> Pedro Larroy Tovar wrote:
>> Hi
>>
>> I can reproduce a crash with 2.6.19-rc6-mm2 triggered when debugging a
>> program with gdb that uses pthreads. No oops or anything strange seems
>> to be printed by the kernel, but the box appears to stop doing disk IO.

> Hm, I wonder if this is related walt's problem running things under gdb?

Jeremy, I redid my git-bisect from scratch and came up with a different
commit for the gdb breakage:

commit f95d47caae5302a63d92be9a0292abc90e2a14e1
Author: Jeremy Fitzhardinge <jeremy@goop.org>
Date:   Thu Dec 7 02:14:02 2006 +0100
[PATCH] i386: Use %gs as the PDA base-segment in the kernel

This commit is the one which causes gdb to halt with this error
no matter what executable I try to run:
Warning:
Cannot insert breakpoint -2.
Error accessing memory address 0xd74b: Input/output error.

I tried to git-revert just this one commit, but I get merge conflicts
I don't how to resolve.

BTW, I just discovered tons of kernel debugging config options which
were turned off -- I just turned several of them on.  Maybe I can give
you better info now.