I am unclear as to what you are asking exactly, but I’ll give it a go.
If your question is whether porting Zephyr code to another RTOS is easy, the answer is: generally it is not, because even if you get the basics running the devil is in the details and corner cases. I would certainly not recommend porting the Zephyr BLE Host or Controller to another RTOS, I’d recommend instead using a BLE stack designed for portability instead of tight coupling.
Regarding the second question I think you are likely confusing layers. GATT services are in the Host, not in the Controller. So your 700 byte limit must be in the Host, which likely means that whatever IC you were connecting via SPI to was running both Host and Controller. That is not a configuration that Zephyr supports natively, because it needs a custom RPC-like layer between the application and the host/controller IC.
From: <users@...> on behalf of "valens.dsilva via lists.zephyrproject.org" <valens.dsilva=revivalanalytics.com@...>
Of the 3 layers running on the Host (App, BLE Host and HCI driver) in the dual chip configuration what is the difficulty in porting each layer over to Microsoft's ThreadX? My host micro will eventually be running
Micrsoft's ThreadX RTOS (with CMSIS2 OS abstraction).
My project is a host micro (STM32) and a nRF52840 (controller mode) to implement a peripheral. The configuration is the dual chip configuration.