The Primary Compute application processors (Cortex-A720AE) are the final processors to be enabled.
As before, you can connect whilst powered down and monitor the point that they are enabled.
You can debug the initialization code and the final Linux Operating System (OS) threads.
Use the following debugger commands in the Primary_init.launch to load the symbols for the BL2 initialization code, setting a breakpoint at bl2_entrypoint.
Note that an address offset is used to specify the Exception Level (EL) that the image is relevant to. If the processor changes Exception Level, the debug information would need to also be loaded to the corresponding EL address space.
For example the processors start in EL3 and move to EL2N when the Linux kernel is enabled.
stop
add-symbol-file /arm-auto-solutions/build/tmp_baremetal/work/fvp_rd_aspen-poky-linux/trusted-firmware-a/2.11.0+git/image/firmware/bl2.elf EL3:0x0
tbreak bl2_entrypoint
Exact paths might differ depending on your build output.
Run to bl2_entrypoint and step through as required.
Symbol loading is Exception Level–aware. If execution changes Exception Level, load symbols into the corresponding EL address space. For example, the processors start in EL3 and transition to EL2N when the Linux kernel is enabled.
Switch to the Primary_Linux.launch connection you created earlier to enable Arm Development Studio OS awareness for the Linux kernel. Load the kernel symbols and set source mapping if your kernel sources are located outside the default paths:
stop
add-symbol-file /arm-auto-solutions/build/tmp_baremetal/work/fvp_rd_aspen-poky-linux/linux-yocto/6.6.54+git/linux-fvp_rd_aspen-standard-build/vmlinux EL2N:0x0
set substitute-path /usr/src/kernel/ /arm-auto-solutions/build/tmp_baremetal/work-shared/fvp-rd-aspen/kernel-source/
Run the FVP until the OS prompt appears.
If you only need kernel debugging, start the model with the debug server and begin execution immediately by adding --run:
kas shell -c "../layers/meta-arm/scripts/runfvp -t tmux --verbose -- --iris-server --iris-port 7100 --run"
Enable the Threads view to inspect kernel threads instead of raw CPUs:
In Debug Control, right-click the Primary_Linux connection and select Display Threads
2. Alternatively, enter thread in the Command pane.
The view changes from listing the 16 application processors to the active OS threads.
You might see a warning like:
WARNING(ROS60): Could not enable OS support as the OS does not appear to be initialized. This might be caused by a mismatch between the loaded symbols and the code on the target or because the OS is not up and running. Enabling OS support will be re-attempted when the target next stops.
This occurs if the OS has not completed boot when you connect; it is safe to ignore and will clear after the next target stop.
You have successfully learnt how to use Arm Development Studio to explore and debug the Arm Zena CSS Reference Software Stack.