TDA4VM: Global uninitialized variable initial value exception

Hi qibin su,

Can you please check the compiler flag and see if you are using "--rom_model" compiler flag to initialize the global variables? 

Regards,

Brijesh

Hi Brijesh,

When I used make -n sdk in sdk/rtos/vision_apps to look at the build parameters, I noticed that mcu2_0 was compiled without the --rom_model build flag. Our compilation rules use the officially provided ones without modification.

make_sdk.txt

Best Regards

Hi Qibin,

Can you please include this flag in tiovx/concerto/compilers/tiarmcgt.mak file, as shown below and check it on failing units?

$(_MODULE)_LDFLAGS  := $($(_MODULE)_CFLAGS) -z --warn_sections --reread_libs --rom_model $($(_MODULE)_LINKER_CMD_FILES)

Regards,

Brijesh

Hi Brijesh,

If an abnormal variable (aewbCtrlPrms) exists in sdk/rtos/imaging/itt_server_remote/src/itt_srvr_remote.c, can modifying the editing rules in sdk/rtos/tiovx also take effect?

Best Regards

Qibin

Hi Brijesh,

I'm sorry for my misunderstanding. I have found the corresponding position in the imaging module. I also want to know what is the value of the uninitialized global variable if the compiler does not add the --rom_model flag?

Hi Qibin,

Yes, if you change it in the tiovx folder, it will also be used for imaging component, as this is linker flag.

For more information, please refer to similar questions on below ticket. Essentially rom_model initializes global variable during boottime. 

(86) --rom_model or --ram_model mode for booting? - Code Composer Studio forum - Code Composer Studio︎ - TI E2E support forums

Regards,

Brijesh

Hi Brijesh,

I have tested the code that adds the --rom_model tag, and the initial value of the variable that is not initialized after mcu2_0 starts is still 0xffff. Is there any way I can verify that this compilation option is valid during compilation? Is there any way to debug a program before the.bss segment is initialized, other than using CCS to check the initial values of variables after the program is started? I also have a question that in SDK7.3 there is no --rom_model or --ram_mode flag by default, how does the program start with global variables and how does it handle uninitialized variables? What is the default value?

Best Regards

Qibin

Hi Qibin,

As far as i recollect, default is ram_model in TI RTOS.

This is strange that this variable is not getting initialized. If you explicitly set this variable to 0x0, does it work fine? 

is it possible to recreate this issue on EVM?

Regards,

Brijesh

Hi Brijesh,

There is no problem if the variable is set to 0 when you define it. This problem is fed back from the factory, and the current probability is that 1 to 2 chips will appear in 10,000 chips, which cannot be repeated on the EVM board.

Best Regards

Qibin

Hi Brijesh,

Two new findings emerged from the recent commissioning.

1. I used CCS to check the memory data before mcu2_0 startup (sbl stage) and after mcu2_0 startup. The data before and after mcu2_0 startup was the same, which means that the memory was not cleared to 0 when McU2_0 started.

2. After I added the globally uninitialized variables, I found that this problem follows memory addresses rather than variables, and MemoryBrowserker found that 0x98523000 to 0x98523ffc could not be initialized to 0.

What might be the problem with these phenomena? Is it caused by DDR anomalies?

Best Regards

Qibin