SW4STM32 and SW4Linux fully supports the STM32MP1 asymmetric multicore Cortex/A7+M4 MPUs

   With System Workbench for Linux, Embedded Linux on the STM32MP1 family of MPUs from ST was never as simple to build and maintain, even for newcomers in the Linux world.
And, if you install System Workbench for Linux in System Workbench for STM32 you can seamlessly develop and debug asymmetric applications running partly on Linux, partly on the Cortex-M4.
You can get more information from the ac6-tools website and download two short videos (registration required) highlighting:

System Workbench for STM32

You are viewing a reply to Keil to OpenSTM32 - Code Size  

Keil to OpenSTM32 - Code Size


In addition to setting optimisation to -Os, I suggest to add (-specs=nano.specs) in linker miscellaneous options.
This will forces the linker to use the nanolib (optimised for size) instead of the standard newlib