Environment
Type of SIM: SoftSIM
GitHub: nrf-softsim
Question
What are the minimal requirements for FLASH, heap and stack usage when using SoftSIM, besides the 8 kB of FLASH for the SoftSIM profile?
How much memory does SoftSIM take up?
Answer
The sample project takes up ~110 kB. This includes SoftSIM, TF-M, Zephyr etc..
Flash
32kb are required for the standard TF-M configuration.
A 32kB flash partition is allocated to hold the ITS, and TF-M Protected Storage.
The perception of how much SoftSIM requires of flash memory, depends on how many TF-M elements can be re-used in your application development, since some of the TF-M allocated flash regions are mostly empty.
If you're looking for way of optimizing memory usage - consider introducing a partitioning scheme within the nRF91 memory.
Heap
Onomondo SoftSIM uses the heap memory pool.
It is expected that
CONFIG_HEAP_MEM_POOL_SIZEis at least 30000.If the target application also uses the heap, please consider adjusting this
Kconfigaccordingly. On average, around 18 kB are used, so you should be able to adjust this down to about 20 kB.
The 30 kB heap allocation of SoftSIM is fixed and cannot be changed while guaranteeing full functionality of the SIM.
The heap allocation can be adjusted an optimized, but make sure that the SIM keeps full functionality in all SIM use cases.
Note: Custom heap allocations are not fully supported by Onomondo and may be difficult to troubleshoot.
Cause
One of the biggest memory consuming functionalities in SoftSIM is its support for OTA SIM profile updates. Removing this functionality would greatly remove the memory requirements of SoftSIM - but doing so would mean that the implementation does not follow UICC and USIM standards.
The code from which SoftSIM is built and exported into the nRF-softsim repository is open source so you could look into that. Unfortunately, this is not a config option currently supported in SoftSIM (onomondo-uicc on GitHub) itself.