[RFC] Observer mode

[Stan Shebs]

Michael Snyder wrote:
> Stan Shebs wrote:
>> Here is another patch that pushes the envelope a bit, and for which I 
>> would like to get some prior agreement that it's a good idea.
>>
>> The basic idea here is that GDB is to be used to look at targets 
>> installed in the field and in use.  In such a situation it may 
>> connect to the target and examine state, but not alter that state or 
>> interrupt anything.  In our particular target, tracing is allowed, 
>> but only using fast tracepoints, because they are done using jumps 
>> and thus act as if they were part of the program; taking a trap, even 
>> for a slow tracepoint, disrupts thread execution unacceptably.  We 
>> have been calling this "observer mode", and the customer's GDB is 
>> actually configured to launch in this mode, to reduce the chance of 
>> accidental stopping - the debugger user has to ask specifically to 
>> change it to normal debugging mode.
>>
>> [...]
>
> How different is this from async mode?
Observer mode includes async mode.  One could call it a "read-only 
non-stop async mode that allows fast tracepoints", although that's 
rather a mouthful. :-)

Stan