[Open SoC Debug] CDM-OR1K implementation

SHIVAM AGGARWAL shivam16195 at iiitd.ac.in
Thu May 17 15:37:25 CEST 2018


Hi,
Thanks for the detailed and informative response for the CDM-OR1K
specification
I think it is the perfect time to work on the implementation of Core Debug
Module.

Few attributes of CDM-OR1K from the spec:

   - Provides a register map for OR1K debug registers: Something similar to
   one in MAM but less complicated (We have already mapped them in
   specification)
   https://github.com/opensocdebug/osd-hw/blob/cc01967f5c685645f4f83510f9710658643b3263/modules/mam/common/osd_mam.sv#L134
   - To allow GDB access to these mapped registers using
   osd_regaccess_layer: Similar to this implementation
   https://github.com/opensocdebug/osd-hw/blob/cc01967f5c685645f4f83510f9710658643b3263/modules/mam/common/osd_mam.sv#L100
   <https://github.com/opensocdebug/osd-hw/blob/cc01967f5c685645f4f83510f9710658643b3263/modules/mam/common/osd_mam.sv#L100>
   - How are the input/output values (input dii_flit debug_in, output logic
   debug_in_ready, output dii_flit debug_out, input debug_out_ready)
   determined? Are these values similar to enable signals?
   - Next we need to ensure that we can interact (i.e., read/write
   operation) with the or1k debug unit effectively. For write, we already have
   an update write register.
   - Debug stall event packetization. Do we need something similar to
   osd_trace_packetization
   <https://github.com/opensocdebug/osd-hw/blob/master/blocks/tracepacket/common/osd_trace_packetization.sv>?

   - In the attached or1200 architecture
   <https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwjloOWE7IzbAhXafX0KHb82B9MQFghGMAM&url=http%3A%2F%2Fwww.cl.cam.ac.uk%2Fresearch%2Fsrg%2Fhan%2FACS-P35%2Fdocuments%2Fopenrisc1200_spec.pdf&usg=AOvVaw1Hk6hwaTdFSBQT_tpihEPW>,
   there is quite a good explanation for debug development interface (Page 48
   onwards). In or1200, there is dbg_op_i[2:0] to choose between different
   operations. But, I couldn't find the one in mor1kx code. I need a little
   more help in that part.
   - Do we need to make changes to the mor1kx code?

All the stuff related to CDM-OR1K will be in this repository:
https://github.com/opensocdebug/osd-hw/tree/osd-next

There is already an issue related to CDM for mor1kx
https://github.com/opensocdebug/osd-hw/issues/22

-Shivam Aggarwal
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