Debug Description: Recommendations for debugger behaviour during sequence execution

[jreineckearm]

Follow-up discussion emerged in #325 :
The debug description specification makes little recommendation about how a debugger should behave while debug sequences are executed. An example brought up in the above linked issue is that debugger implementations might continue polling debug status registers while a sequence is executed. And how this should behave during specific debugger operations like reset.

We should add a section in the spec outlining such recommended behavior. Making a start with the above example.

For the particularly mentioned scenario, the question to answer is whether a debugger that regularly polls the CPU and debug connection state to potentially recover from a connection loss should continue this

• during all sequences.
• only for (or not for) specific sequences.
• only for (or not for) specific debugger operations like reset.
• based on a control bit set by the sequence itself. Which apparently would result not only in a recommendation.