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Debugging U-Boot with Ashling RiscFree

Introduction

RiscFree* is Ashling’s Eclipse* C/C++ Development Toolkit (CDT) based integrated development environment (IDE) for Altera® FPGAs Arm*-based HPS and RISC-V based Nios® V processors.

This page demonstrates how to use RiscFree* to debug U-Boot SPL and U-Boot.

For further information about RiscFree*, consult Ashling RiscFree* IDE for Altera® FPGAs User Guide.

Prerequisites

The following are needed:

  • Host PC with:
    • 64 GB of RAM. Less will be fine for only exercising the binaries, and not rebuilding the GSRD.
    • Linux OS installed. Ubuntu 22.04LTS was used to create this page, other versions and distributions may work too
    • Serial terminal (for example GtkTerm or Minicom on Linux and TeraTerm or PuTTY on Windows)
    • Altera® Quartus® Prime Pro Edition Version 24.3.1

You will also need to compile the Agilex 5 GHRD Linux Boot Example targeting the HPS Enablement board, as described here.

Debug U-Boot

1. Build the example design specified in the Prerequisites section.

2. Write the SD card image $TOP_FOLDER/sd_card/sdcard.img to the micro SD card and insert it on the slot on the HPS Enablement Board.

3. Set MSEL dipswitch to JTAG, as specified in the design from the Prerequisites section, then power cycle the board. That will ensure the device is not configured from QSPI.

4. Go to the folder where the example was built, add the Quartus and RiscFree* tools in the path:

cd $TOP_FOLDER
export QUARTUS_ROOTDIR=~/intelFPGA_pro/24.3.1/quartus/
export PATH=$QUARTUS_ROOTDIR/bin:$QUARTUS_ROOTDIR/linux64:$QUARTUS_ROOTDIR/../qsys/bin:$QUARTUS_ROOTDIR/../riscfree/RiscFree:$PATH
5. Configure the device with the 'debug' SOF, which contains an empty loop HPS FSBL, designed specifically for a debugger to connect afterwards:

quartus_pgm -c 1 -m jtag -o "p;agilex5_soc_devkit_ghrd/output_files/ghrd_a5ed065bb32ae6sr0_hps_debug.sof"

6. Start RiscFree* Eclipse using a new workspace in the current folder:

cd $TOP_FOLDER
RiscFree -data workspace &

7. In Eclipse, go to Run > Debug Configurations, this will open the Debug Configurations window.

8. In the Debug Configurations window, select Ashling Arm Hardware Debugging on the left panel, right-click it then select New Configuration from the menu.

9. Edit the configuration as follows

  • Change the Name to "Debug U-Boot"
  • Go to the Debugger tab
  • Select the Debug Probe from the drop down to match your board
  • Click on the Auto-detect Scan Chain to discover the Arm cores
  • Check the first Cortex-A55 in the list to enable debugging for it

The window will look similar to this:

10. Go to the Startup tab, and change the configuration as follows:

  • Uncheck Load image
  • Uncheck Load symbols
  • Uncheck Set breakpoint at
  • Uncheck Resume

The window will look similar to this:

Then add in the Run Commands box the following commands that will enable you to load U-Boot SPL and start debugging it:

interrupt
delete breakpoints
set breakpoint always-inserted on
set mem inaccessible-by-default on
mem 0x00000000 0x0007FFFF rw
mem 0x80000000 0xFFFFFFFF rw
mem 0x880000000 0xFFFFFFFFFF rw
set confirm off
restore u-boot-socfpga/spl/u-boot-spl-dtb.bin binary 0x0
symbol-file u-boot-socfpga/spl/u-boot-spl
set $pc=0x0
step

If want to run U-Boot SPL up to where it decides which image to load next, add the following lines to the previous step:

thb board_boot_order
continue

If then you want to load U-Boot and start debugging it, add the following lines to the previous step, which will load U-Boot, run it until the memory is relocated, perform the relocation, then drop to debugging mode

delete breakpoints
set spl_boot_list[0]=0
set $pc=$lr
set $x0=0
restore u-boot-socfpga/u-boot.itb binary 0x82000000
symbol-file "u-boot-socfpga/u-boot" 
thb relocate_code
continue
delete breakpoints
set $offset = ((gd_t*)$x18)->reloc_off
symbol-file
add-symbol-file u-boot-socfpga/u-boot -o $offset
thb board_init_r
continue

If you only want to run U-Boot, without debugging it, then remove the "thb board_init_r" from the above script, so it would not stop at the beginning of U-Boot, and instead continue running it.

11. Click the Debug button on the bottom of the window. Eclipse will warn that the program file was not specified. Click Yes to proceed with the launch.

12. Eclipse will suggest to move to the debug perspective. Click Switch to accept:

13. Eclipse will then run the specified sequence of instructions.

When the instructions for debugging U-Boot SPL were used, after running them, Eclipse will show the U-Boot SPL started:

When the instructions for debugging U-Boot were used, after running them, Eclipse will show the U-Boot started:

At this point, all the debugging features of Eclipse are available, such as:

  • Viewing and editing variables and registers
  • Setting breakpoints
  • Controlling execution: run step by step, step into functions
Last update: February 7, 2025
Created: February 7, 2025