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

Redirect printf for STM32L476 Discovery?

Just simply download the STM32cubeL4.zip archive. You’ll find it on the STM web page. Latest version I think is 1.2.0.
This includes bunch of examples for the L4. It comes with SW4STM project file. Look for UART/UART_Printf.

Just load it in ac6/system workbench. Build it and try it.