NCS 3.0.0: Linker errors when building LVGL project

[Ladivin]

Dear DevZone,

While porting our project from NCS 2.9.1 to NCS 3.0.0, I ran into linker errors when building LVGL. The linker reports that it cannot find functions defined in C:\ncs\v3.0.0\modules\lib\gui\lvgl\src\misc\lv_circle_buf.c. It appears that this file is not included in C:\ncs\v3.0.0\zephyr\modules\lvgl\CMakeLists.txt. After manually adding ${LVGL_DIR}/src/misc/lv_circle_buf.c to zephyr_library_sources() to that file, I was able to build the project without any linker errors.

Is this a bug or am I doing something wrong? 

Thanks,

Ladivin

[Kazi Afroza Sultana]

Hello Ladivin,

Did you try to run the sample on custom board? Can you please send me the project file to me?

[Ladivin]

Helo Kazi,

many thanks for you quick response.

Yes, we do have a custom board, but in the mean time I was able to reproduce this using nRF5340 DK. The simplest configuration to reproduce the issue is as follows (the project is attached as a zip file) :

- Take hello world sample from Zephyr (from NCS 3.0.0) as a baseline

- Add CONFIG_LVGL=y and CONFIG_DISPLAY=y to the prj.conf of this sample

- Add app.overlay with a dummy display to the project. This overlay was taken from another zephyr sample

- Add a call to any LVGL function that references functions from lv_circle_buf.c into your main -> in my case I just put lv_iter_destroy(NULL); 

-Build this for nRF5340DK

- Observe the linker error e.g. in function `lv_iter_destroy':
C:/ncs/v3.0.0/modules/lib/gui/lvgl/src/misc/lv_iter.c:98: undefined reference to `lv_circle_buf_destroy'

As stated before, this can be fixed by adding ${LVGL_DIR}/src/misc/lv_circle_buf.c to zephyr_library_sources() to C:\ncs\v3.0.0\zephyr\modules\lvgl\CMakeLists.txt

I also tried this with NCS 3.0.1 but it made no difference. 

Thanks!

Ladivin

hello_world_LVGL.zip

[Kazi Afroza Sultana]

Hello Ladivin,

I have tried to run your attached sample on nRf5340DK and I was able to run the sample. There were some warnings related to warning: implicit declaration of function 'lv_iter_destroy' [-Wimplicit-function-declaration].  

Adding the following header files in the main.c file, solved the issue

#include <lvgl.h>
#include <zephyr/device.h>
#include <zephyr/devicetree.h>
#include <zephyr/drivers/display.h>

This is the output I got

I have not seen any other way to fix this issue. I have asked team. I will get back to you soon.

Thanks.

BR

Kazi

[jakkra]

I have the exact same issue, however only when putting LVGL into external XIP flash using:

zephyr_code_relocate(LIBRARY modules__lvgl LOCATION EXTFLASH_TEXT NOCOPY)

zephyr_code_relocate(LIBRARY modules__lvgl LOCATION RAM_DATA)

Did you find any hints?
Must be something related. It worked in 2.9.1 for me.

Adding 

zephyr_library_sources(${LVGL_ROOT_DIR}/src/misc/lv_circle_buf.c) in modules/lib/gui/lvgl/env_support/cmake/zephyr.cmake did not make any difference.

arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.2.0/../../../../arm-zephyr-eabi/bin/ld.bfd: modules/lvgl/libmodules__lvgl.a(lv_iter.c.obj): in function `lv_iter_destroy':
modules/lib/gui/lvgl/src/misc/lv_iter.c:98: undefined reference to `lv_circle_buf_destroy'
arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.2.0/../../../../arm-zephyr-eabi/bin/ld.bfd: modules/lvgl/libmodules__lvgl.a(lv_iter.c.obj): in function `lv_iter_make_peekable':
modules/lib/gui/lvgl/src/misc/lv_iter.c:112: undefined reference to `lv_circle_buf_create'
arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.2.0/../../../../arm-zephyr-eabi/bin/ld.bfd: modules/lvgl/libmodules__lvgl.a(lv_iter.c.obj): in function `lv_iter_next':
modules/lib/gui/lvgl/src/misc/lv_iter.c:122: undefined reference to `lv_circle_buf_is_empty'
arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.2.0/../../../../arm-zephyr-eabi/bin/ld.bfd: modules/lib/gui/lvgl/src/misc/lv_iter.c:123: undefined reference to `lv_circle_buf_read'
arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.2.0/../../../../arm-zephyr-eabi/bin/ld.bfd: modules/lib/gui/lvgl/src/misc/lv_iter.c:124: undefined reference to `lv_circle_buf_skip'
arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.2.0/../../../../arm-zephyr-eabi/bin/ld.bfd: modules/lvgl/libmodules__lvgl.a(lv_iter.c.obj): in function `lv_iter_peek':
modules/lib/gui/lvgl/src/misc/lv_iter.c:145: undefined reference to `lv_circle_buf_size'
arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.2.0/../../../../arm-zephyr-eabi/bin/ld.bfd: modules/lib/gui/lvgl/src/misc/lv_iter.c:148: undefined reference to `lv_circle_buf_fill'
arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.2.0/../../../../arm-zephyr-eabi/bin/ld.bfd: modules/lib/gui/lvgl/src/misc/lv_iter.c:152: undefined reference to `lv_circle_buf_peek_at'
arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/12.2.0/../../../../arm-zephyr-eabi/bin/ld.bfd: modules/lvgl/libmodules__lvgl.a(lv_iter.c.obj): in function `lv_iter_peek_advance':
modules/lib/gui/lvgl/src/misc/lv_iter.c:162: undefined reference to `lv_circle_buf_capacity'

Edit:
Found the issue, the file is missing in this file zephyr/modules/lvgl/CMakeLists.txt

I was also adding the zephyr_library_sources to the wrong cmake file, did it in the one zephyr.cmake inside lvgl, which is not the one used.

It's added in this upstream commit: https://github.com/zephyrproject-rtos/zephyr/commit/0b0fd7d674f67a358eb9532ea2b26b8493235bcb