Welcome to the Realtime Linux

In this documentation, you will learn:

• Introduction to meta-qcom-realtime layer
• How to sync and build the Realtime Linux Layer
• Flash image

Let's get started!

Introduction

The Realtime layer provides recipes and configuration required to run linux kernel as a real time kernel. The real time kernel runs with preemption fully enabled through a config, CONFIG_PREEMPT_RT=y The layer supports linux-kernel-qcom-rt recipe that fetches and builds linux kernel for supported machine, this layer appends to kernel, the upstream PREEMPT_RT patches based on kernel version and enables the realtime configurations.

How to sync and build the Realtime Linux Layer

Host Setup and Download the Yocto Project BSP

Refer to QCOM Linux Yocto BSP releases setup the host environment and download Yocto Project BSP.

mkdir [release]
cd [release]
repo init -u https://github.com/qualcomm-linux/qcom-manifest -b [branch name] -m [release manifest]
repo sync -c -j8

Example

To download the qcom-6.6.52-QLI.1.3-Ver.1.1 release

repo init -u https://github.com/qualcomm-linux/qcom-manifest -b qcom-linux-kirkstone -m qcom-6.6.52-QLI.1.3-Ver.1.1.xml
repo sync

Run below command to download "meta-qcom-realtime" layer in [release] directory where you have downloaded Yocto Project BSP.

cd [release]
git clone https://github.com/qualcomm-linux/meta-qcom-realtime -b [meta-qcom-realtime release tag] layers/meta-qcom-realtime

Note: Find the latest "meta-qcom-realtime" layer release tag names at https://github.com/qualcomm-linux/meta-qcom-realtime/tags

Examples

To download the qcom-6.6.52-QLI.1.3-Ver.1.1_realtime-linux-1.0 release tag

git clone https://github.com/qualcomm-linux/meta-qcom-realtime -b qcom-6.6.52-QLI.1.3-Ver.1.1_realtime-linux-1.0 layers/meta-qcom-realtime

Build Realtime Linux Layer

export SHELL=/bin/bash
export EXTRALAYERS="meta-qcom-realtime"
MACHINE=qcs6490-rb3gen2-core-kit DISTRO=qcom-wayland source setup-environment

Run the following command to compile and generate flashable image with Yocto Project BSP plus REALTIME LINUX layer

bitbake qcom-multimedia-image

Image output path: $[release]/build-qcom-wayland/tmp-glibc/deploy/images/qcm6490/qcom-multimedia-image.

Flash the image

To flash the generated build, see the Flash images

Reference

Standard Yocto environment

QCOM Linux Yocto BSP releases