Multilib vs. no multilib
The mhwd script contains - line 134-147 - a check which flags the installation as multilib if /etc/mhwd-x86_64.conf is not present.
It is expected that if the iso-profile contains multilib="false" then lib32-* files will not be present and that expectation is met.
However the check in mhwd will always set the internal variable MHWD64_IS_LIB32="true" as the file /etc/mhwd-x86_64.conf is not present. One would expect that file to be created by the buildiso script or its associated libraries but none of these libraries contains any reference to that config.
When mhwd executes line 287-293, the package list will be extended with files from the DEPENDS_64 env variable. Files which is not present and the driver installation fails.
if [ "${ARCH}" == "x86_64" ] && [ "${DEPENDS_64}" != "" ]; then
if [ "${MHWD64_IS_LIB32}" == "true" ];then
PACKAGES="${PACKAGES} ${DEPENDS_64}"
else
PACKAGES="${PACKAGES}"
fi
fi
The DEPENDS_64 is set when the db file is sourced
# Dependencies
DEPENDS="xf86-video-ati
xf86-video-amdgpu
xf86-video-intel
xf86-video-nouveau
vulkan-intel
vulkan-radeon
libva-mesa-driver
libva-vdpau-driver
mesa-vdpau"
DEPENDS_64="lib32-vulkan-intel
lib32-vulkan-radeon
lib32-libva-vdpau-driver
lib32-mesa-vdpau"