Multi-core

In Zephyr 3.2.0 see `zephyr/include/zephyr/drivers/ipm.h` for some starting points to understand inter-processor messaging.

• https://ostconf.com/system/attachments/files/000/001/688/original/Brodkin_Linux_Piter_presentation.pdf?1570035188

One of two or three Zephyr 3.2.0 sample apps which touch on multi-core firmware design:

• ./subsys/ipc/openamp/boards/lpcxpresso55s69_cpu0.overlay

Zephyr sys init run levels

Likely for another local article, excerpt from `zephyr/include/zephyr/init.h`:

 18 /*
 19  * System initialization levels. The PRE_KERNEL_1 and PRE_KERNEL_2 levels are
 20  * executed in the kernel's initialization context, which uses the interrupt
 21  * stack. The remaining levels are executed in the kernel's main task.
 22  */
 23 
 24 #define _SYS_INIT_LEVEL_PRE_KERNEL_1    0
 25 #define _SYS_INIT_LEVEL_PRE_KERNEL_2    1
 26 #define _SYS_INIT_LEVEL_POST_KERNEL     2
 27 #define _SYS_INIT_LEVEL_APPLICATION     3
 28 
 29 #ifdef CONFIG_SMP
 30 #define _SYS_INIT_LEVEL_SMP             4
 31 #endif