Re: [RFC] fix gdb.threads/non-stop-fair-events.exp timeouts

[Pedro Alves <palves@redhat.com>]

On 09/09/2015 05:08 PM, Sandra Loosemore wrote:
> On 09/08/2015 10:30 AM, Pedro Alves wrote:
>>
>> Yeah, I've seen this before with a local series I use for debugging
>> software single-step things that implements software single-stepping
>> on x86.  I just re-tried it now after rebasing that series to
>> current mainline, and I still see the time outs against gdbserver.
>>
>> AFAICS, nios2 is a software single-step target that does not implement
>> displaced stepping either.  I had a patch for this that I had
>> never posted.  See attached.
>>
> 
> Hmmm, these two patches are not working for me.  The trouble is that 
> this part:
> 
>> +gdb_test_multiple "si" $msg {
>> +    -re "displaced pc to.*$gdb_prompt $" {
>> +	set displaced_stepping_enabled 1
>> +    }
>> +    -re ".*$gdb_prompt $" {
>> +    }
>> +}
> 
> is causing the target to step from main to pthread_self, which is in a 
> different file.  This causes the subsequent breakpoint commands to fail, 
> and things go south from there:

OK, I got "lucky" on x86 and a stepi runs some instruction before the call.
Could you try simply replacing the "si" with "next" ?  It doesn't matter
whether that issues several single-steps or not.  What matters is that gdb
tries to step past the breakpoint that is set at the current PC (from the
earlier runto_main).  We're trying to figure out if gdb uses displaced
stepping for that.

Thanks,
Pedro Alves