Overlay files are dtb fragments that, upon boot, patch the main dtb
board file to enable Raspberry Pi hardware extension (commonly known as
Raspberry HATs) to work.
This mechanism works fine for the bionic/raspi2 kernel, but it didn't
work for the raspi2 arm64 variant since our dtb files are missing
symbols there.
This patch instruct the device tree compiler to add symbols to the dtb
files during the 'make dtbs' target, and fix the overlay patching
mechanism for bionic/raspi2 arm64.
The resulting increase in size is negligible (~30kb for the whole kernel
package).
Signed-off-by: Paolo Pisati <email address hidden>
Acked-by: Stefan Bader <email address hidden>
Acked-by: Colin Ian King <email address hidden>
Signed-off-by: Khalid Elmously <email address hidden>