layer-contents.md: Update documentationag_rpi3bplus

* Raspberry Pi 3B+ support mentioned
* Add info about linux-firmware-raspbian

Signed-off-by: Andrei Gherzan <andrei@gherzan.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/docs/layer-contents.md b/docs/layer-contents.md
index 223a3b0..0ba60f5 100644
--- a/docs/layer-contents.md
+++ b/docs/layer-contents.md
@@ -11,6 +11,8 @@
 * raspberrypi-cm (dummy alias for raspberrypi)
 * raspberrypi-cm3 (dummy alias for raspberrypi2)
 
+Note: The raspberrypi3 machines include support for Raspberry Pi 3B+.
+
 ## Images
 
 * rpi-test-image
@@ -20,3 +22,13 @@
 For other uses it's recommended to base images on `core-image-minimal` or
 `core-image-base` as appropriate. The old image names (`rpi-hwup-image` and
 `rpi-basic-image`) are deprecated.
+
+## WiFi firmware blobs
+
+Be aware that the WiFi firmwares for the supported boards are not provided by
+`linux-firmware` but by a custom recipe which only packages the needed blobs
+for these boards. This is because the upstream `linux-firmware` doesn't support
+or has outdated files for the blobs we need. The recipe
+`linux-firmware-raspbian` is based on a fork of `linux-firmware` which
+includes everything we need in order to fully support the WiFi hardware. All
+machines define `MACHINE_EXTRA_RRECOMMENDS` accordingly.