Using JTAG

Table of contents:

Prerequisites

FlashPro6 programmer from Microchip
Linux, or Windows with WSL
Microchip SoftConsole v6.5
- <SoftConsolePath> will be required. Note it down on installation.
  For Windows WSL, the default path is /mnt/c/Microchip/SoftConsole-v6.5/

Starting the OpenOCD server

First we need to start the OpenOCD server. That will enable communication with PolarFireSoC's Risc-V cores via the FlashPro6 programmer:

Open a new user session in terminal
Run <SoftConsolePath>/openocd/bin/openocd -c "set DEVICE MPFS" --file board/microsemi-riscv.cfg
Expected output below. OpenOCD will log into this session when new events appear.

user@device:~$ /mnt/c/Microchip/SoftConsole-v6.5/openocd/bin/openocd.exe -c "set DEVICE MPFS" --file board/microsemi-riscv.cfg
xPack OpenOCD (Microchip SoftConsole build), x86_64 Open On-Chip Debugger 0.10.0+dev-00859-g95a8cd9b5-dirty (2020
-10-19-17:30)
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html 
MPFS
Info : only one transport option; autoselect 'jtag'
Info : Hardware thread awareness created
do_board_reset_init
Info : Listening on port 6666 for tcl connections
Info : Listening on port 4444 for telnet connections
Info : No Embedded FlashPro6 (revision B) devices found
fpServer v17 waiting for incoming connections on the port 3334 with API v5
Info : 1 1614681740419 microsemi_flashpro_server.c:1751 microsemi_flashpro_initialize() FlashPro ports available:
 138018D
Info : 2 1614681740419 microsemi_flashpro_server.c:1752 microsemi_flashpro_initialize() FlashPro port selected:
 138018D
Info : clock speed 6000 kHz
Info : JTAG tap: mpfs.cpu tap/device found: 0x0f81a1cf (mfg: 0x0e7 (GateField), part: 0xf81a, ver: 0x0)
Info : datacount=2 progbufsize=16
Info : Disabling abstract command reads from CSRs.
Info : Core 0 could not be made part of halt group 1.
Info : Examined RISC-V core; found 5 harts
Info :  hart 0: XLEN=64, misa=0x8000000000101105
Info :  hart 1: currently disabled
Info :  hart 2: currently disabled
Info :  hart 3: currently disabled
Info :  hart 4: currently disabled
Info : datacount=2 progbufsize=16
Info : Disabling abstract command reads from CSRs.
Info : Core 1 could not be made part of halt group 1.
Info : Examined RISC-V core; found 5 harts
Info :  hart 0: currently disabled
Info :  hart 1: XLEN=64, misa=0x800000000014112d
Info :  hart 2: currently disabled
Info :  hart 3: currently disabled
Info :  hart 4: currently disabled
Info : datacount=2 progbufsize=16
Info : Disabling abstract command reads from CSRs.
Info : Core 2 could not be made part of halt group 1.
Info : Examined RISC-V core; found 5 harts
Info :  hart 0: currently disabled
Info :  hart 1: currently disabled
Info :  hart 2: XLEN=64, misa=0x800000000014112d
Info :  hart 3: currently disabled
Info :  hart 4: currently disabled
Info : datacount=2 progbufsize=16
Info : Disabling abstract command reads from CSRs.
Info : Core 3 could not be made part of halt group 1.
Info : Examined RISC-V core; found 5 harts
Info :  hart 0: currently disabled
Info :  hart 1: currently disabled
Info :  hart 2: currently disabled
Info :  hart 3: XLEN=64, misa=0x800000000014112d
Info :  hart 4: currently disabled
Info : datacount=2 progbufsize=16
Info : Disabling abstract command reads from CSRs.
Info : Core 4 could not be made part of halt group 1.
Info : Examined RISC-V core; found 5 harts
Info :  hart 0: currently disabled
Info :  hart 1: currently disabled
Info :  hart 2: currently disabled
Info :  hart 3: currently disabled
Info :  hart 4: XLEN=64, misa=0x800000000014112d
Info : Listening on port 3333 for gdb connections

GNU Debugger

To run GDB:

Open a new user session terminal

Run the following multi-line single command

<SoftConsolePath>/riscv-unknown-elf-gcc/bin/riscv64-unknown-elf-gdb \
    -ex "set mem inaccessible-by-default off" \
    -ex "set $target_riscv=1" \
    -ex "set arch riscv:rv64"

Expected output:

user@device:~$ /mnt/c/Microchip/SoftConsole-v6.5/riscv-unknown-elf-gcc/bin/riscv64-unknown-elf-gdb.exe -ex "set mem inaccessible-by-default off" -ex "set $target_riscv=1" -ex "set arch riscv:rv64"
C:\Microchip\SoftConsole-v6.5\riscv-unknown-elf-gcc\bin\riscv64-unknown-elf-gdb.exe: warning: Couldn't determine
a path for the index cache directory.
GNU gdb (xPack GNU RISC-V Embedded GCC (Microsemi SoftConsole build), 64-bit) 9.1
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html >
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "--host=x86_64-w64-mingw32 --target=riscv64-unknown-elf".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://github.com/sifive/freedom-tools/issues >.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/ >.

For help, type "help".
Type "apropos word" to search for commands related to "word".
A syntax error in expression, near `=1'.
The target architecture is assumed to be riscv:rv64
(gdb)

Connecting GDB with OpenOCD:

To start debugging the RISC-V cores you have to first connect to the remote target. At the GDB console run: target remote localhost:3333

(gdb) target remote localhost:3333
Remote debugging using localhost:3333
warning: No executable has been specified and target does not support
determining executable automatically.  Try using the "file" command.
0x000000002022051c in ?? ()
(gdb)

OpenOCD console should report the following:

Info : accepting 'gdb' connection on tcp/3333
Info : New GDB Connection: 1, Target mpfs.hart0_e51, state: halted

Usufull GDB commands:

examine

examine / x reads memory content. Example:

(gdb) x/16xw 0x60030000
0x60030000:     0xdead2137      0x00000000      0x00000000      0x00000000
0x60030010:     0x00000000      0x00000000      0xa5a5a5a5      0xa5a5a5a5
0x60030020:     0xdead2137      0x00000000      0x00000000      0x00000000
0x60030030:     0x00000000      0x00000000      0xa5a5a5a5      0xa5a5a5a5
(gdb)

set

set writes memory content. Example:

(gdb)  set *((int*)0x60030004)=0xFFFF0001
The riscv_frame_cache's start_addr is 0 (from the get_frame_func).
Forcing it to the value of the PC (0x000000002022051c) to avoid the riscv_scan_prologue reading between 0-99 addresses.
(gdb)  set *((int*)0x60030008)=0xFFFF0000
The riscv_frame_cache's start_addr is 0 (from the get_frame_func).
Forcing it to the value of the PC (0x000000002022051c) to avoid the riscv_scan_prologue reading between 0-99 addresses.
(gdb)

restore

restore writes memory content with data from file. Example:

(gdb) restore logo.bin binary 0x60038000 0 0x10000
Restoring binary file logo.bin into memory (0x60038000 to 0x60040000)
(gdb)

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