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Yocto Build Linux from source code - VAR-SOM-AM62

Introduction

This guide walks through the process for manually building and installing Linux from source. It is derived from TI's Build Linux guide

Fetch source code and install dependencies

This section describes the one time process to install the toolchains and fetch the necessary source code for building Linux.

Install Toolchains to home directory

$ cd ~
$ wget https://developer.arm.com/-/media/Files/downloads/gnu-a/9.2-2019.12/binrel/gcc-arm-9.2-2019.12-x86_64-arm-none-linux-gnueabihf.tar.xz && \
   tar -Jxvf gcc-arm-9.2-2019.12-x86_64-arm-none-linux-gnueabihf.tar.xz -C $HOME && \
   wget https://developer.arm.com/-/media/Files/downloads/gnu-a/9.2-2019.12/binrel/gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu.tar.xz && \
   tar -Jxvf gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu.tar.xz -C $HOME

Fetch Source Code

Setup a working directory

$ export WORKDIR=~/am62x-var-som-linux
$ mkdir ${WORKDIR}

Fetch the Linux source:

$ cd $WORKDIR
$ git clone https://github.com/varigit/ti-linux-kernel -b ti-linux-5.10.y_var01 ti-linux-kernel

Fetch the kernel driver for the PowerVR Rogue GPU:

$ cd $WORKDIR
$ git clone https://git.ti.com/git/graphics/ti-img-rogue-driver -b linuxws/dunfell/k5.10/1.15.6133109_unified_fw_pagesize ti-img-rogue-driver
$ cd ti-img-rogue-driver && \
  git checkout 1dd6291a5cad4f2b909fc2a14bd717a3bc5f0bb2 && \
  cd ../

Build Linux out of Yocto tree

After fetching the source code and installing dependencies, you may return to $WORKDIR anytime and follow these steps to build Linux:

Setup the environment:

Export the working directory

$ export WORKDIR=~/am62x-var-som-linux

Export variables for building Linux

$ export PATH=$HOME/gcc-arm-9.2-2019.12-x86_64-aarch64-none-linux-gnu/bin:$PATH

Build Kernel image, modules, and device trees:

Change to kernel directory:

$ cd $WORKDIR/ti-linux-kernel

Configure the Kernel:

Clean directory:
$ make mrproper

Create .config from am62x_var_defconfig
$ make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- -j$(nproc) am62x_var_defconfig

Optional: Make changes to .config and save to am62x_var_defconfig
$ make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- -j$(nproc) menuconfig
$ make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- -j$(nproc) savedefconfig
$ cp defconfig arch/arm64/configs/am62x_var_defconfig

Build Kernel:

Build All:
$ make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- -j$(nproc)

Build Image only:
$ make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- -j$(nproc) Image

Build modules only:
$ make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- -j$(nproc) modules

Build device trees only:
$ make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- -j$(nproc) dtbs

Build Kernel drivers for the PowerVR Rogue GPU:

$ cd ${WORKDIR}/ti-img-rogue-driver
$ make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- -j$(nproc) \
    KERNELDIR=${WORKDIR}/ti-linux-kernel \
    BUILD=release PVR_BUILD_DIR=am62_linux \
    WINDOW_SYSTEM=wayland

Install new kernel

Create a directory to install the kernel, device trees, and modules:

Optional: delete any old installation from previous builds:
$ rm -rf $WORKDIR/rootfs

Create new directory:
$ mkdir -p $WORKDIR/rootfs/boot

Copy the Image and device trees to the rootfs:

$ cd $WORKDIR/ti-linux-kernel
$ cp arch/arm64/boot/Image $WORKDIR/rootfs/boot/
$ cp arch/arm64/boot/dts/ti/k3*am*var-som*.dtb $WORKDIR/rootfs/boot/

Install the modules to the rootfs:

$ make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- -j$(nproc) \
    modules_install INSTALL_MOD_PATH=$WORKDIR/rootfs

Install the GPU driver to the rootfs:

$ cd $WORKDIR/ti-img-rogue-driver
$ make ARCH=arm64 CROSS_COMPILE=aarch64-none-linux-gnu- -j$(nproc) \
    KERNELDIR=${WORKDIR}/ti-linux-kernel \
    BUILD=release PVR_BUILD_DIR=am62_linux \ 
    WINDOW_SYSTEM=wayland \
    -C ${WORKDIR}/ti-linux-kernel M=${WORKDIR}/ti-img-rogue-driver/binary_am62_linux_wayland_release/target_aarch64/kbuild \
    INSTALL_MOD_PATH=${WORKDIR}/rootfs \ 
    INSTALL_MOD_STRIP=1 \
    modules_install

Deploy new kernel

You can deploy $WORKDIR/rootfs to a running device:

Option 1: Copy to a local SD card mounted at /media/user/rootfs/:
$ sudo cp -r $WORKDIR/rootfs/* /media/user/rootfs/

Option 2: Copy to a running device over ethernet
$ tar czf - -C $WORKDIR/rootfs . | ssh root@<ip address> 'tar xzf - --no-same-owner -C /'

Yocto Build Linux TI

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