Re: [RFC] New thread testcase.

[Michael Snyder <msnyder@redhat.com>]

Manoj,

It sounds from your eplanation like the "step" part of your test
is not required, since your bug shows up without it.  I explained
in my previous msg why I was concerned about that test.  What
would you think of removing the step?

Michael

Manoj Iyer wrote:
> oh! sorry abt that... got confused btwn 'bugs'...
> 
> The kernel bug was causing gdb to fail when passing a 32bit address to the
> kernel.  this was causing 32 bit gdb to fail in linux_test_for_tracefork()
> by always returning second_pid = 0 in the PTRACE_GETEVENTMSG call.
> 
> this resulted in linux_enable_event_reporting() not setting the PTRACE
> fork options for the pid and then the thread never received a SIGSTOP.
> 
> John Engel, kernel developer, debugged and fixed this problem in the
> kernel after we reported this GDB problem to him...
> 
> So, when you debug a multi-threaded app with 32bit GDB on a PPC64 system,
> and you set a break point at the thread function and tried to step, you
> get the message "reading register pc (#64): No such process." for example:
> 
> Breakpoint 1, main (argc=1, argv=0xffffe464) at tbug.c:31
> 31        for (n = 0; n < N; ++n)
> (gdb) cont
> Continuing.
> [New Thread 1078217504 (LWP 26708)]
> tf(0): begin
> [New Thread 1082411808 (LWP 26709)]
> after create
> tf(1): begin
> tf(0): end
> [Thread 1078217504 (LWP 26708) exited]
> tf(1): end
> [Thread 1082411808 (LWP 26709) exited]
> after join
> 
> Program exited normally.
> (gdb) clear main
> Deleted breakpoint 1
> (gdb) break tf
> Breakpoint 2 at 0x10000594: file tbug.c, line 15.
> (gdb) run
> Starting program: /home/public/test-tools/gdb/tbug
> [Thread debugging using libthread_db enabled]
> [New Thread 1074020384 (LWP 26710)]
> reading register pc (#64): No such process.
> (gdb) cont
> Continuing.
> reading register pc (#64): No such process.
> 
> Thanks
> ----- ----
> Manoj Iyer
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> + Cognito ergo sum +
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 
> On Tue, 10 Aug 2004, Andrew Cagney wrote:
> 
> 
>>>>Manoj,
>>>>
>>>>>You've got me curious.  Do any of the existing tests exercise this bug
>>>>>(manythreads.exp comes to mind)?   Oh, and what is the bug? :-)
>>>>>
>>>
>>>
>>>This is a generic kernel bug (in ptrace() )that causes ptrace to fail on
>>>Power 64 systems.  Please look at PR#1712 for details.
>>
>>Unfortunatly 1712 doesn't answer my question.  What is the bug?  What
>>causes ptrace to fail?
>>
>>Andrew
>>
>>
>>
> 
>