[Buildroot] Building packages for Cortex M4

[Thomas Petazzoni]

Hello Andrey,

On Wed, 8 Dec 2021 17:46:58 +0100
Andrey Nechypurenko <andreynech at gmail.com> wrote:

> I am currently playing with Avenger96 Board which is powered by
> ST32MP157 with A7 and M4 cores. Part of my system is the firmware for
> the M4 microcontroller which should be compiled with a corresponding
> variant of gcc (not the one used to compile the rest of the system)
> and placed in /lib/firmware in the rootfs/image.
> 
> I am wondering if this kind of scenario (two different
> cross-compilers) is supported by Buildroot and if yes, is there any
> documentation on how to do it? If there is no "standard" way to
> achieve this, I would appreciate any recommendations.

Yes, it is possible by installing a separate bare-metal compiler using
an additional host package in Buildroot.

You can see https://github.com/bootlin/buildroot-external-st is able to
build the M4 examples from ST. Note that this BR2_EXTERNAL works with a
few patches on Buildroot itself, available at
https://github.com/bootlin/buildroot/commits/st/2021.02. One of the
change is precisely on the bare metal toolchain package.

Best regards,

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com