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retroSoC/docs/hazard3-debug.md
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maksyuki 2b6819449c feat: enhance test coverage and update system control interfaces
- Added  interface to  and implemented error handling for register writes.
- Introduced a new test for AXI4 address gate functionality in .
- Updated clock and reset domain assertions in  to reflect new domain names.
- Modified expected outputs in  to include new clock domains.
- Adjusted chip configuration assertions in  to account for additional power pads.
- Enhanced memory map tests in  with new definitions and includes.
- Updated pin mapping tests in  to include new reference clock pads.
- Improved script tools tests in  to ensure correct validation of extension bindings.
- Refined system control tests in  to include new clock control interface.
- Updated USB2 packet RAM tests in  to include new SRAM definitions.
- Enhanced user extensions tests in  to validate new product extension configurations.
- Adjusted user IP register parity tests to use legacy extensions.
- Updated Yosys synthesis recipe tests to reflect changes in STA period calculations.
2026-08-30 08:10:59 +08:00

2.4 KiB

Hazard3 Management-Core Debug

Scope

The fixed Hazard3 management core always exposes a standard RISC-V JTAG Debug Transport Module (DTM) on five ASIC pads: TCK, TMS, TDI, TRST_n, and TDO. The default JTAG ID code is 0xDEADBEEF. Set JTAG_IDCODE=<eight hexadecimal digits> to use a board-specific value.

The Debug Module (DM) controls only the management Hazard3 hart. It supports abstract register and memory commands and has HAVE_SBA=0, so it never becomes a second SoC bus master. Debugger memory operations execute through the halted hart and remain subject to the AXI4 interconnect access policy. MPW user cores, peripherals, clocks, and pad control stay outside the debug-reset scope.

The product Vexii HP hart can own shared JTAG only while held in reset. C0-C3 are software-selected only in the mini-ver-mpw compatibility profile; they are not management-core options and do not have a management Debug Module.

Reset And Clocking

The DTM runs in the JTAG TCK domain. Hazard3's APB async bridge transfers DMI transactions into the LP DM domain. The canonical clock/reset map constrains TCK at 10 MHz and declares JTAG asynchronous to LP.

The DM ndmreset and hart-reset requests pass through mgmt_debug_reset. It waits until the management AHB-Lite-to-AXI4 bridge is idle, then resets only that bridge and the management hart. The DTM, DM, RCU, MPW user cores, and all peripherals remain live. Reset release is synchronized with the common rst_sync cell and acknowledged only after the local reset is released.

Verilator Acceptance

The ihp130-debug profile builds a minimal SRAM-resident firmware image and starts a loopback remote-bitbang endpoint inside the Verilator harness. The locked OpenOCD and RISC-V GDB binaries then verify JTAG identification, hart register access, SRAM read/write, ELF download, a software breakpoint, resume, and single-step.

make CONFIG=configs/ci/ihp130-debug.mk SIMU=VERILATOR debug-sim

The flow writes result-debug-sim.json and the emulator, OpenOCD, and GDB logs under build/<variant>/sim/verilator/debug/. It passes only when GDB prints DEBUG_GDB_PASS. This is a functional simulation check, not board-level JTAG signal-integrity, DFT, or production debug-lock signoff.

The OpenOCD configuration is rtl/mini/dv/verilator/openocd/retrosoc_hazard3.cfg; its remote-bitbang port is supplied by the test driver, so concurrent local runs do not share a fixed TCP port.