[FAQ] AM62x & AM64x: How to use CCS to debug a running M4F core that was started by Linux?

Nick Saulnier

I am using AM62x or AM64x.

I want to use Code Composer Studio (CCS) to debug a program running on the M4F. The M4F was already initialized and loaded by Linux. I want CCS to attach to the M4F and start debugging the code that is already running (i.e., I do NOT want CCS to restart the M4F or load new code onto the M4F).

Q: Why would I want CCS to attach to the M4F without resetting the M4F?

If the remote core (i.e., M4F) uses RPMsg communication with Linux, then some information about RPMsg is included in the M4F firmware. However, some RPMsg information needs to be provided by Linux. That information is typically provided by the Linux RemoteProc and RPMsg drivers while Linux is booting up. If CCS reloads firmware onto the M4F after Linux has already booted, then CCS overwrites the RPMsg information from Linux. If the RPMsg information from Linux is deleted, then RPMsg with the Linux cores will not work.

If CCS needs to be the one to load the M4F firmware (instead of Linux), and if the firmware uses Linux RPMsg, consider shutting down and restarting the Linux IPC drivers as described here.

Q: What if the remote core firmware does not use RPMsg? Can CCS reset the M4F in that case without messing with the Linux IPC drivers?

Yes, CCS can reset the M4F and load new firmware into the M4F if the M4F firmware does not need information from Linux. Steps for loading and running remote core firmware from CCS are covered in the MCU+ SDK documentation under "CCS Launch, Load and Run".

Q: Does this example also work for R5F cores?

The same concept also applies to R5F cores. However, some of the specific steps might need to be changed.

Q: What if I have another question about multicore subjects?

For other FAQs about multicore subjects, please reference Sitara multicore development and documentation

UPDATE January 2024: The information in this FAQ has been added to the processor academy modules. This FAQ will not be maintained going forward.
Please find the latest information in the processor's academy > Multicore module > Multicore Development > Application Development on Remote Cores > How to debug a remote core while Linux is running:
AM62x
AM62Ax
AM64x

over 1 year ago

+1 Nick Saulnier over 1 year ago

TI__Guru 72495 points

Hardware & Software information

This example was tested on the AM62x SK EVM board, with software from the Linux AM62x SDK 8.5 and the MCU+ AM62x SDK 8.5.

Pre-work:

Download the Linux and MCU+ SDKs

AM62x: https://www.ti.com/tool/PROCESSOR-SDK-AM62X

AM64x: https://www.ti.com/tool/PROCESSOR-SDK-AM64X

Get Linux running on the EVM

Follow the AM62x Starter Kit EVM Quick Start Guide in order to get Linux running on the AM62x EVM.

Setup MCU+ SDK & CCS

Follow the MCU+ SDK documentation steps for "Getting Started" > "Download, Install and Setup SDK and Tools" and "Download, Install and Setup CCS". SDK 8.5 steps are here.

+1 Nick Saulnier over 1 year ago

TI__Guru 72495 points

Step 1: Build the remote core project in CCS

Take the MCU+ IPC project examples/drivers/ipc/ipc_rpmsg_echo_linux/am62x-sk/m4fss0-0_freertos.

Open the project in CCS. Build the project.

You can find steps for how to build a project in CCS in the MCU+ SDK docs. SDK 8.5 link is here.

+1 Nick Saulnier over 1 year ago

TI__Guru 72495 points

Step 2: copy the binary into the Linux filesystem, and update the links

Copy the .out file from CCS into the Linux filesystem somewhere under /lib/firmware.

Boot up the EVM. In the terminal, update the M4 symbolic link to point to the new .out file.

Steps for how to update a remote core symbolic link are covered in the AM62x Linux Academy here.

+1 Nick Saulnier over 1 year ago

TI__Guru 72495 points

Step 3: make sure the firmware is running properly

Reboot the EVM.

Run tests to make sure that the RPMsg example is running properly. Follow the steps to run the IPC Example here.

0 Nick Saulnier over 1 year ago

TI__Guru 72495 points

Step 4: attach CCS

Plug in the JTAG cable, and start the AM62x Target Configuration.

Connect to the core BLAZAR_Cortex_M4F_1

Load Symbols, as shown in this image:

Select the same .out file that was copied to the Linux filesystem, and that Linux loaded to the M4:

+1 Nick Saulnier over 1 year ago

TI__Guru 72495 points

Step 5: Set a breakpoint in CCS

Open ipc_rpmsg_echo.c in the "CCS Debug" view.

Go to the "ipc_recv_task_main".

Do you see the "while(1)" loop? This is where the ipc_recv_task_main task will be when the RTOS runs the task.

Set a breakpoint somewhere INSIDE the while(1) loop:

Go to the line of code where you want CCS to halt the program. Right click on the line number, and select Breakpoint (Code Composer Studio) > Breakpoint:

You should now see a blue circle on that line number. The blue circle tells you that you have a breakpoint there.

+1 Nick Saulnier over 1 year ago

TI__Guru 72495 points

Step 6: Testing the breakpoint

Now let's run some tests.

In CCS, make sure that the M4F core is running (not suspended).

In the linux terminal, run the rpmsg_char_simple command. Something like this:
rpmsg_char_simple -r 9 -n 5

In CCS, you should now see that the M4F is suspended at the breakpoint that you set.

In the Linux terminal, you should see that the terminal has paused partway through the test. The Linux terminal will not get any RPMsg example updates until you unpause the M4.

You can now move through the IPC code in CCS. As you move through the code, you will see more lines show up in the Linux terminal.

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[FAQ] AM62x & AM64x: How to use CCS to debug a running M4F core that was started by Linux?