OSES-Assignment: A Layer for a custom Yocto-Distribution

RasperryPi3 + QemuARM

LAYER INSTRUCTIONS FOR QEMU ARM

This repo contains a layer including the two recipes: one for building and deploying the APP and one for the cDD hearth rate monitor, which is made of two components: 1)A Linux character-based driver (cDD) used to access a “virtual” Photopletismography(PPG) sensor, 2)Linux user application (APP)

This README file contains information on the contents of the 'OSES-assignment' layer. Please see the corresponding sections below for details.

I suppose that it has been done a previous yocto setup & build for ARM target NAMED "build-qemuarm", this instructions just show how to integrate a new layer in a yocto distribution.

STARTING FROM your poky directory (cd path_to_poky):

0:Clone the repo, and source to the build environment directory

cd path_to_poky
git clone https://github.com/Luca-Dalmasso/OSES-Assignment.git
--Now should have a directory: OSES-Assignment, which is our layer
source oe-init-build-env build-qemuarm

1: Add the layer

bitbake-layers add-layer ../OSES-Assignment

2: Check if the Layer has been added (optional if you have done #1)

cd conf
cat bblayers.conf
--check that after the field 'BBLAYERS ?= "' you have something like 'poky/OSES-Assignment \'
--if not then write it manually

3: Add to the image the driver+user application

--add at the end of 'local.conf' the following lines:
IMAGE_INSTALL_append = " driver"
KERNEL_MODULE_AUTOLOAD += " driver"
IMAGE_INSTALL_append = " userapp"

4: Compile new image

bitbake core-image-minimal

5: Test the application

runqemu qemuarm
--login as root
--you can use command: dmesg, to see if 'driver' kernel module has been correctly loaded
--find out what is the Major number: i suppose it is 251 0 [major,minor]
cat proc/devices | grep driver
--create the associated device file named virtual_sensor
mknod /dev/virtual_sensor c 251 0
--now the application can comunicate to the device file, start the application:
userapp

LAYER INSTRUCTIONS FOR RASPBERRYPI3, STARTING FROM QEMUARM BUILD

--in order to install everithing on the rasperry only few more steps are needed. 
--this will take a lot of time to compile (from scratch) everything for the new machine.

6: Prerequisites:

--You will "convert" all the previuous work just to be compatible with the RPI3

7: Add new remote-layers to poky

--Needed in order to build a custom yocto distro for RPi3
git clone -b dunfell git://git.openembedded.org/meta-openembedded
git clone -b dunfellhttps://github.com/meta-qt5/meta-qt5
git clone -b dunfell git://git.yoctoproject.org/meta-security
git clone -b dunfell git://git.yoctoproject.org/meta-raspberrypi

--edit 'bblayers.conf' file, in order to add new layers --> THE SAME FILE OF STEP #2
--should looks like this:

POKY_BBLAYERS_CONF_VERSION = "2"

BBPATH = "${TOPDIR}"
BBFILES ?= ""

BBLAYERS ?= " \
/poky/meta \
/home/usr/poky/meta-poky \
/poky/meta-yocto-bsp \
/poky/meta-openembedded/meta-oe \
/poky/meta-openembedded/meta-multimedia \
/poky/meta-openembedded/meta-networking \
/poky/meta-openembedded/meta-python \
/poky/meta-raspberrypi \
/poky/OSES-Assignment \

"

8: Add new configurations to local.conf

--same file as #3
--Comment the line MACHINE ?= "qemuarm", now we are changing architecture
--add following lines:
MACHINE ?= "raspberrypi3"
ENABLE_UART = "1"
IMAGE_FSTYPES = "tar.xz ext3 rpi-sdimg"

9: Modify driver.bb file in the driver layer

--bitbake needs to compile this kernel module to be compatible with raspberry machine so: cd ../../OSES-Assignment/recipes-example/driver --modify the "COMPATIBLE_MACHINE" field like this: COMPATIBLE_MACHINE = "raspberrypi3" --compile everything bitbake core-image-minimal

10: Micro SD setup

--you cannot test this on qemu as before.
--Suppose that your SD card is on /dev/sdb, (check it with lsblk command)
sudo dd if=tmp/deploy/images/raspberrypi3/core-image-minimal-raspberrypi3.rpi-sdimg of=/dev/sdb bs=1M