Flows

Memory initialization

Main goal of Memory initialization is to unmap unused memory after firmware load and create heaps for supported memory zones.

@startuml box "SOF" #LightBlue participant "MPP Memory Manager" as mpp_memory_manager end box box "Zephyr" #LightGreen participant "Memory Manager" as zephyr_memory_manager participant "Memory Management Driver" as memory_management_driver end box box "Hardware" #LightGrey participant "Memory" as hw_memory end box -> memory_management_driver: sys_mm_drv_mm_init activate memory_management_driver memory_management_driver -> memory_management_driver: read unused_main_mem_start_marker\nfrom linker note right: The marker is used to\n identify where base firmware\n ends in memory (text, data, bss) memory_management_driver -> memory_management_driver: sys_mm_drv_unmap_region(unused_main_mem_start, unused_size) activate memory_management_driver opt If architecture support granular memory banks power control memory_management_driver -> hw_memory: power down unused memory banks deactivate memory_management_driver end deactivate memory_management_driver -> mpp_memory_manager: mpp_mem_init activate mpp_memory_manager mpp_memory_manager -> mpp_memory_manager: read memory zones\nbase address and size loop for each memory region create heap mpp_memory_manager -> zephyr_memory_manager: k_heap_init\n(heap, mem*, size) activate zephyr_memory_manager return end deactivate mpp_memory_manager @enduml

Figure 61 Memory initialization flow

Memory allocation

The common memory allocation is expected to use one of the available memory zones via Zephyr Heap that was created during initialization.

@startuml box "SOF" #LightBlue participant "Component Management" as component_management participant "MPP Memory Manager" as mpp_memory_manager end box box "Zephyr" #LightGreen participant "Zephyr Memory Manager" as zephyr_memory_manager end box activate component_management component_management -> mpp_memory_manager: rmalloc(mem_zone, flags, caps, size) activate mpp_memory_manager mpp_memory_manager -> mpp_memory_manager: find memory heap that\nmatch zone and caps mpp_memory_manager -> zephyr_memory_manager: k_heap_alloc (heap, size) activate zephyr_memory_manager return mpp_memory_manager --> component_management @enduml

Figure 62 Memory allocation example flow

Memory allocation directly using Memory Management Driver

In specific use cases (e.g. Dynamic Component Load) it may be required to allocate memory directly using Memory Management Driver to control what virtual address will be mapped to physical memory.

@startuml box "SOF" #LightBlue participant "Library Manager" as library_manager end box box "Zephyr" #LightGreen participant "Memory Management Driver" as memory_management_driver end box box "Hardware" #LightGrey participant "Memory" as hw_memory end box activate library_manager library_manager -> memory_management_driver: sys_mm_drv_map_region\n(virt*, phys=NULL, size, flags) activate memory_management_driver memory_management_driver -> memory_management_driver: allocate memory phys pages opt if phys memory pages require power up memory_management_driver -> hw_memory: power up memory banks end return @enduml

Figure 63 Example memory allocation using Memory Management Driver

Dynamic Component Load

The loadable components are stored in Loadable Library memory zone and can be loaded on instantiate request to System memory. The components load to System memory is optional and integrator can indicate if the components can be executed directly from the Loadable Library memory zone.

@startuml box "Host" #LightGreen participant "Driver" as host_driver end box box "Media Processing Pipelines Layer" #LightSkyBlue participant "Component Manager" as component_manager participant "Library Manager" as lib_manager participant "MPP Memory Manager" as mpp_memory_manager end box box "Zephyr RTOS" #LightBlue participant "Memory Management Driver" as memory_management_driver end box box "Hardware" #LightGrey participant "Memory" as hw_memory end box host_driver -> lib_manager: Load Library activate lib_manager lib_manager -> mpp_memory_manager: rmalloc(MEM_ZONE_RUNTIME, flags=NULL, MEM_CAPS_LOADABLE_LIBRARY, size) activate mpp_memory_manager return address to store library lib_manager --> host_driver deactivate lib_manager host_driver -> lib_manager: Transfer library over DMA\nto given address host_driver -> component_manager: Instantiate Component activate component_manager opt if Component is Loadable and it is first instance component_manager -> lib_manager: Load component activate lib_manager loop repeat for Component TEXT, RODATA lib_manager -> lib_manager: read Component virtual address and size from manifest lib_manager -> memory_management_driver: sys_mm_drv_map_region(virt*, phys=NULL, size, flags=NULL) activate memory_management_driver memory_management_driver -> memory_management_driver: allocate free phys pages opt power up memory banks for allocated phys pages memory_management_driver -> hw_memory: power up memory banks end memory_management_driver --> lib_manager deactivate memory_management_driver lib_manager -> lib_manager: read Component address offset from library manifest lib_manager -> lib_manager: mem_copy(virt*, library_store_addr + offset, size) lib_manager -> memory_management_driver: sys_mm_drv_update_region(virt*, size, flags= CODE / RODATA) activate memory_management_driver note right: update region flags to prevent overwrite return end opt if Component has BSS lib_manager -> memory_management_driver: sys_mm_drv_map_region(virt*, phys=NULL, bss_size, flags) activate memory_management_driver memory_management_driver -> memory_management_driver: allocate free phys pages opt power up memory banks for allocated phys pages memory_management_driver -> hw_memory: power up memory banks end memory_management_driver --> lib_manager deactivate memory_management_driver end lib_manager --> component_manager deactivate lib_manager end component_manager -> component_manager: Instantiate Component component_manager --> host_driver @enduml

Figure 64 Dynamic component load and instantiation flow