[Buildroot] [PATCH 1/1] package/rpi-firmware: add overlays/README

[Yann E. MORIN]

Tim, All,

On 2022-10-31 11:46 +0000, Tim Gover spake thusly:
> If a custom os_prefix directory is specified then the Raspberry Pi
> firmware probes for the README file in overlays directory.
> 
> Since the README file is small let's include it, otherwise,

197KiB is _not_ small. In fact, the README is bigger than every dtbo,
and accounts for ~25% of the size of all dtbo combined.

> the firmware won't recognize the overlays directory if the user
> later moves it to an os_prefix specific sub-directory.

What is the goal here, in the context of Buildroot, where we only
install one set of overlays?

If a user moved the overlays, they already have a script that does that,
so they should also ensure that script properly prepares config.txt to
specify the proper os_prefix, and so it is just a matter of adding a
'touch' on the README in the same script.

Regards,
Yann E. MORIN.

> From
> https://www.raspberrypi.com/documentation/computers/config_txt.html#overlay_prefix
> 
> Unless ${os_prefix}${overlay_prefix}README exists, overlays are shared
> with the main OS (i.e. os_prefix is ignored).
> 
> Signed-off-by: Tim Gover <tim.gover at raspberrypi.com>
> ---
>  package/rpi-firmware/rpi-firmware.mk | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/package/rpi-firmware/rpi-firmware.mk b/package/rpi-firmware/rpi-firmware.mk
> index d4d1d07b3f..908d7def6a 100644
> --- a/package/rpi-firmware/rpi-firmware.mk
> +++ b/package/rpi-firmware/rpi-firmware.mk
> @@ -48,6 +48,7 @@ define RPI_FIRMWARE_INSTALL_DTB_OVERLAYS
>  	$(foreach ovldtb,$(wildcard $(@D)/boot/overlays/*.dtbo), \
>  		$(INSTALL) -D -m 0644 $(ovldtb) $(BINARIES_DIR)/rpi-firmware/overlays/$(notdir $(ovldtb))
>  	)
> +	$(INSTALL) -D -m 0644 $(@D)/boot/overlays/README $(BINARIES_DIR)/rpi-firmware/overlays/
>  	$(INSTALL) -D -m 0644 $(@D)/boot/overlays/overlay_map.dtb $(BINARIES_DIR)/rpi-firmware/overlays/
>  endef
>  else
> -- 
> 2.25.1
> 
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