They fit in the same part of the address space as DRAM would be, and
are coherent (because they are not cacheable).
They are currently limited to single cores without DRAM. We intend
to lift both restrictions, probably when we add support for
heterogeneous tiles.
This usually shouldn't be used in Tiles that are meant to be P&R'd once
and multiply instantiated, as their RTL would no longer be homogeneous.
However, it is useful for conditionalizing RTL generation for
heterogeneous tiles.
- The DebugTransportModuleJtag is written in Verilog. It probably could be written in
Chisel except for some negative edge clocking requirement.
- For real implementations, the AsyncDebugBusTo/From is insufficient. This commit
includes cases where they are used, but because they are not reset asynchronously,
a Verilog 'AsyncMailbox' is used when p(AsyncDebug) is false.
- This commit differs significantly from the earlier attempt. Now, the
DTM and synchronizer is instantiated within Top, as it is a real piece of
hardware (vs. test infrastructure).
-TestHarness takes a parameter vs. creating an entirely new TestHarness class.
It does not make sense to instantiate TestHarness when p(IncludeJtagDTM) is false,
and it would not make sense to insantiate some other TestHarness if p(IncludeJtagDTM)
is true.
To build Verilog which includes the JtagDTM within Top:
make CONFIG=WithJtagDTM_...
To test using gdb->OpenOCD->jtag_vpi->Verilog:
First, install openocd (included in this commit)
./bootstrap
./configure --prefix=$OPENOCD --enable-jtag-vpi
make
make install
Then to run a simulation:
On a 32-bit core:
$(ROCKETCHIP)/riscv-tools/riscv-tests/debug/gdbserver.py \
--run ./simv-TestHarness-WithJtagDTM_... \
--cmd="$OPENOCD/bin/openocd --s $OPENOCD/share/openocd/scripts/" \
--freedom-e300-sim \
SimpleRegisterTest.test_s0
On a 64-bit core:
$(ROCKETCHIP)/riscv-tools/riscv-tests/debug/gdbserver.py \
--run ./simv-TestHarness-WithJtagDTM_... \
--cmd="$OPENOCD/bin/openocd --s $OPENOCD/share/openocd/scripts/" \
--freedom-u500-sim \
SimpleRegisterTest.test_s0
Initial cut
checkpoint which compiles and runs but there is some off-by-1 in the protocol
Debugging the clock crossing logic
checkpoint which works
Clean up the AsyncMailbox black box
