Given the mutual exclusivity of CONFIG_ZONE_DMA and CONFIG_ZONE_DEVICE, I've set CONFIG_ZONE_DMA=y for amd64 lowlatency and both i386 flavours . CONFIG_ZONE_DEVICE=y for amd64 generic. These settings are not relevant for other architectures.
Given the mutual exclusivity of CONFIG_ZONE_DMA and CONFIG_ZONE_DEVICE, I've set CONFIG_ZONE_DMA=y for amd64 lowlatency and both i386 flavours . CONFIG_ ZONE_DEVICE= y for amd64 generic. These settings are not relevant for other architectures.