# VCU118 GDB Debug Flow

Use this after the VCU118 bitstream is already programmed.

Terminal 1:

```sh
make -C targets/fpga/vcu118 debug-openocd
```

Terminal 2:

```sh
make -C targets/fpga/vcu118 uart-listen UART_PORT=/dev/ttyUSB2
```

Terminal 3:

```sh
make -C targets/fpga/vcu118 debug-load APP=hello_uart
```

Expected UART output starts with:

```text
Rocket Chip VCU118 hello printf
```

Notes:

- OpenOCD uses Xilinx BSCAN, not a direct external RISC-V TAP.
- `rocket_bscan_dmi_tunnel.sv` must be present in the FPGA bitstream.
- If OpenOCD reports `LIBUSB_ERROR_BUSY`, close Vivado Hardware Manager or kill
  stale `hw_server` processes.