Define a section to consistently place rtt

RE: Define a section to consistently place rtt

Anthony Ambuehl — Tue, 11 Feb 2025 23:47:27 GMT

I'm using NCS 2.6.0, possibly its a difference in the versions.

In my environment I find in modules/debug/segger/SEGGER/SEGGER_RTT.c this code:

#ifndef SEGGER_RTT_BUFFER_SECTION
#if defined(SEGGER_RTT_SECTION)
#define SEGGER_RTT_BUFFER_SECTION SEGGER_RTT_SECTION
#endif
#endif

<snip>

#if defined(SEGGER_RTT_SECTION) || defined (SEGGER_RTT_BUFFER_SECTION)
#if ((defined __GNUC__) || (defined __clang__))
#define SEGGER_RTT_PUT_SECTION(Var, Section) __attribute__ ((section (Section))) Var
#elif (defined __ICCARM__) || (defined __ICCRX__)
#define SEGGER_RTT_PUT_SECTION(Var, Section) RTT_PRAGMA(location=Section) \
Var
#elif (defined __CC_ARM)
#define SEGGER_RTT_PUT_SECTION(Var, Section) __attribute__ ((section (Section), zero_init)) Var
#else
#error "Section placement not supported for this compiler."
#endif
#else
#define SEGGER_RTT_PUT_SECTION(Var, Section) Var
#endif

<snip>



#if defined(SEGGER_RTT_SECTION)
#define SEGGER_RTT_PUT_CB_SECTION(Var) SEGGER_RTT_PUT_SECTION(Var, SEGGER_RTT_SECTION)
#else
#define SEGGER_RTT_PUT_CB_SECTION(Var) Var
#endif

#if defined(SEGGER_RTT_BUFFER_SECTION)
#define SEGGER_RTT_PUT_BUFFER_SECTION(Var) SEGGER_RTT_PUT_SECTION(Var, SEGGER_RTT_BUFFER_SECTION)
#else
#define SEGGER_RTT_PUT_BUFFER_SECTION(Var) Var
#endif

Does your environment have the same?

RE: Define a section to consistently place rtt

zpm1066 — Mon, 10 Feb 2025 03:09:43 GMT

Anthony Ambuehl

Hi, I tried to place the RTT control block as per your note above.

In the project folder's CMakeLists.txt, I added:

zephyr_compile_definitions(SEGGER_RTT_SECTION="rtt")

and in the overlay in the project boards folder, added:

/ {
    sram@2003FB00 {
        compatible = "zephyr,memory-region";
        reg = <0x2003FB00 0x500>;
        zephyr,memory-region = "rtt";
        status = "okay";
    };
};

However, I got the following in the zephyr_pre0.map and the SEGGER_RTT isn't being located to the specified address. I'm using NCS 2.9.0.

What am I missing? How do we specify SEGGER_RTT to use the "rtt" memory region?

btw - I have RTT logging both for the app and MCUBoot. Other than a minor glitch, app/MCUBoot logging seems to ok.

*** Booting MCUboot v2.1.0-dev-12e5ee106034 ***
*** Using nRF Connect SDK v2.9.0-7787b2649840 ***
*** Using Zephyr OS v3.7.99-1f8f3dc29142 ***
I: Starting bootloader
I: Primary image: magic=good, swap_type=0x4, copy_done=0x1, image_ok=0x1
I: Secondary image: magic=good, swap_type=0x2, copy_done=0x3, image_ok=0x3
I: Boot source: none
I: Image index: 0, Swap type: test
I: Starting swap using move algorithm.
I: Bootloader chainload address offset: 0x16000
I: Jumping to the first image slot
44] <inf> mcumgr_img_grp: Erased 0x1000 bytes of image slot trailer
[00:02:37.191,741] <inf> mcuboot_util: Image index: 0, Swap type: none
[00:02:37.192,108] <inf> mcuboot_util: Image index: 0, Swap type: test
[00:02:46.936,798] <inf> mcuboot_util: Image index: 0, Swap type: test
0m
[00:34:59.613,952] <inf> mcuboot_util: Image index: 0, Swap type: revert
*** Booting My Application v1.3.0 - unknown commit ***
*** Using nRF Connect SDK v2.9.0-7787b2649840 ***
*** Using Zephyr OS v3.7.99-1f8f3dc29142 ***
[00:00:08.496,063] <inf> mcuboot_util: Image index: 0, Swap type: revert

Thanks!

RE: Define a section to consistently place rtt

Anthony Ambuehl — Wed, 08 Jan 2025 00:37:53 GMT

I didn't need to add anything for the rtt block in the partition manager static configuration. The zephyr,memory-region did it all.

RE: Define a section to consistently place rtt

Anthony Ambuehl — Mon, 06 Jan 2025 18:37:10 GMT

I also need to get this to work with sysbuild for a multi image build. I'm hoping this will work in my pm_static.yml:

rtt:
address: 0x2003FB00
end_address: 0x20040000
region: sram_primary
size: 0x500

RE: Define a section to consistently place rtt

Anthony Ambuehl — Mon, 06 Jan 2025 18:23:40 GMT

I think I have this working. In my board dts file I added:

/ {

sram@2003FB00 {

compatible = "zephyr,memory-region";

reg = <0x2003FB00 0x500>;

zephyr,memory-region = "rtt";

status = "okay";

};

In my application CMakeLists.txt I added:

zephyr_compile_definitions(SEGGER_RTT_SECTION="rtt")

When I run a single image build I see this in my zephyr/zephyr_pre0.map

rtt             0x000000002003fb00      0x4b8
                0x000000002003fb00                __rtt_start = .
 *(SORT_BY_ALIGNMENT(rtt))
 rtt            0x000000002003fb00      0x4b8 modules/segger/libmodules__segger.a(SEGGER_RTT.c.obj)
                0x000000002003ff10                _SEGGER_RTT
 *(SORT_BY_ALIGNMENT(rtt.*))
                0x000000002003ffb8                __rtt_end = .
                0x00000000000004b8                __rtt_size = (__rtt_end - __rtt_start)
                0x000000002003fb00                __rtt_load_start = LOADADDR (rtt)