How to debug OP-TEE (What is OPTEE console?)

[NKim.3]

Hi, I want to debug OP-TEE on STM32 MPU board.

Using 'st_stm32mp157f_dk2_demo_defconfig' configuration of STM32MP1 Buildroot external tree(buildroot-external-st), We indirectly confirmed that OP-TEE is built and ran normally on the board with Buildroot.

I would like to customize the code in optee-os using the APIs provided by OP-TEE. Before I do that, I'd like to try to print out whether the code works at a certain point in time and the results of the modified code using the OP-TEE API and track the function calls.

I followed the OP-TEE official document, but the debug log is not captured. In addition, the document only guides you on how to track function calls.

Then, while reading the [How to debug OP-TEE] page on the STM32MP1 Wiki(wiki/How_to_debug_OP-TEE), I realized that the debug log is printed on the OP-TEE console(Marked by the cursor in the attached picture).

 

So what I'm curious about are two things.

1) Where do the OP-TEE debug results go? (What is an OP-TEE console?)

2) Is there any way to output values inside opted-os? (If not, I wonder if there is a shared memory that can be used between OPTEE and Linux.)

[Olivier GALLIEN · Accepted solution]

Hi @NKim.3​ 

What we call Optee console is the serial link specified as stdout-path in the Device tree

	aliases {
		serial0 = &uart4;
		serial1 = &usart3;
		serial2 = &uart7;
	};
 
	chosen {
		stdout-path = "serial0:115200n8";
	};

It's usually Uart4 by default and shared by all BSP component and Linux.

Op-tee trace usually looks like this with [I-D]/TC prefix:

I/TC: Early console on UART#4

Hope it help

Olivier

[NKim.3]

Thank you:)