E.4. Varying Target Capabilities

Some targets don't support floating-point, and some would rather not have to deal with long long operations. Also, different targets will have different stack sizes, and different bytecode buffer lengths.

Thus, GDB needs a way to ask the target about itself. We haven't worked out the details yet, but in general, GDB should be able to send the target a packet asking it to describe itself. The reply should be a packet whose length is explicit, so we can add new information to the packet in future revisions of the agent, without confusing old versions of GDB, and it should contain a version number. It should contain at least the following information:

• whether floating point is supported

• whether long long is supported

• maximum acceptable size of bytecode stack

• maximum acceptable length of bytecode expressions

• which registers are actually available for collection

• whether the target supports disabled tracepoints