reproduce (this is a W=1 build):
        git remote add jassibrar-mailbox https://git.kernel.org/pub/scm/linux/kernel/git/jassibrar/mailbox.git
        git fetch jassibrar-mailbox for-next
        git checkout jassibrar-mailbox/for-next
        b4 shazam https://lore.kernel.org/r/20250415182826.3905917-3-justin.chen@broadcom.com
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/mailbox/ drivers/mfd/ drivers/platform/x86/amd/