no stack trace with 2.6.11 and gdb 6.3

[Rich Coe <Richard.Coe@med.ge.com>]

I have been investigating a problem we found here, which initially
exactly matched the problem reported here:

    https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=146087

    1. Start a 32-bit app on a x86_64 system
    2. attach with gdb
    3. backtrace starting in a system call doesn't work

Our versions:
    kernel: 2.6.11.11
    gdb: 6.3.0.0-1.21

After reviewing the patch made to bug#146087, I found that I can get
a valid traceback if I issue the following request:

    add-symbol-file-from-memory 0xffffe000

The interesting part is that this also failing on x86 systems, not just
x86_64.

If you start an application from within gdb on the command line, 
the following line is printed out:
    Loaded system supplied DSO at 0xffffe000

Which is apparently some internal gdb function executing the 
'add-symbol-file-from-memory' request that does not happen when attaching
to a running process.

I have a linux-2.6.7 system with gdb 6.0post-0.20040223.19rh that doesn't
have this problem.  

We have also replicated this problem on a current FC3 standard distribution
with gdb-6.3.0.0-1.21. The latest/last FC3 gdb shows the problem noted in the
bug report identified above.

How did we get this problem from gdb 6.0 to gdb 6.3 ?

-- 
Rich Coe		richard.coe@med.ge.com
General Electric Healthcare Technologies
Global Software Platforms, Computer Technology Team