Compiling the Kernel (Kernel 5.15)

Prerequisites

You have installed the Kernel source code (already installed in Docker) and the toolchain:

sudo -E apt install  nv-driveos-linux-*_amd64.deb
sudo -E apt install nv-driveos-foundation-toolchains-*_amd64.deb

The top-level directory layout looks as follows:

drive-foundation
drive-linux
Drive-linux_src
toolchains                

To Compile the Kernel

1. Set up the environment macros: The LOCAL_VERSION environment variable appends -tegra to the kernel version and modules.

   export ARCH=arm64
   export CROSS_COMPILE=${PWD}/toolchains/aarch64--glibc--stable-2022.03-1/bin/aarch64-buildroot-linux-gnu-
   export LOCALVERSION="-tegra"

2. Set the kernel source directory as the current working directory:

   cd <top>/drive-linux/kernel/source/oss_src

3. Enter the following command to apply the rt-patches.

   cd kernel/scripts
   bash generic-rt-patch.sh apply-patches
   cd ../../ 

4. Create an output directory, and then configure the kernel for the board:

   mkdir out-linux
   make -C kernel O=${PWD}/out-linux clean

   If prompted, install the packages:

   1. sudo apt-get install imagemagick graphviz dvipng python3-venv fonts-noto-cjk latexmk
                  librsvg2-bin texlive-xetex

   2. /usr/bin/python3 -m venv sphinx_2.4.4
      . sphinx_2.4.4/bin/activate

   3. pip install -r  <top>/drive-linux/kernel/source/oss_src/kernel/Documentation/sphinx/requirements.txt

   4. sudo apt-get install flex

   5. sudo apt-get install bison

5. Add the following command:

   make -C kernel O=${PWD}/out-linux defconfig

6. Build the kernel:

   make -j3 -C kernel O=${PWD}/out-linux

   Note: If the preceding command fails, enter the make command without the j<number> option.
7. Build OOT modules:

   make -C ${PWD}/out-linux M=${PWD}/nvidia-oot/  srctree.nvidia-oot=${PWD}/nvidia-oot/ 
   srctree.nvidia=${PWD}/nvidia-oot  V=1 modules CONFIG_TEGRA_OOT_MODULE=m

8. To flash the built images, copy the uncompressed (Image) kernel images to the kernel top directory with the following command:

   sudo cp ${PWD}/out-linux/arch/arm64/boot/Image
   <top>/drive-linux/kernel/preempt_rt/images/

   CAUTION: Before copying the new kernel images, create a backup of the default kernels provided.
9. Consolidate the built kernel modules in the build directory with the following commands:

   export INSTALL_MOD_PATH=${PWD}/out-linux
   make -C kernel O=${PWD}/out-linux modules_install
   make -C ${PWD}/out-t186ref-linux M=${PWD}/nvidia-oot/ modules_install

10. Copy the built modules to the root file system path with the following commands:
    1. Copy the built modules to the SDK kernel modules path:

       sudo cp -a ${PWD}/out-linux/lib/modules/* <top>/drive-
       linux/kernel/preempt_rt/modules

    2. To copy the updated modules into the root file system, use the following Build-FS steps:
       1. Create a Build-FS JSON with the following content:

          {
              "OS": "linux",
              "Output": "driveos-updated-rfs",
              "Base": "\${BASE_DIR}/targetfs.img",
              "CopyTargets": [
                  "\${COPYTARGETYAML_DIR}/copytarget-kernel-modules.yaml"
              ]
          }

       2. Execute Build-FS with the preceding configuration to rebuild the filesystem. Set NV_WORKSPACE to opt of SDK install directory (containing drive-linux directory).

          $ sudo -E /usr/bin/python3 -B /opt/nvidia/driveos/common/filesystems/build-
            fs/17/bin/build_fs.py -w ${NV_WORKSPACE}/ -i $PWD/update_rfs.CONFIG.json -o ${NV_WORKSPACE}/drive-linux/filesystem/targetfs-images/
          $ sudo rm -f ${NV_WORKSPACE}/drive-linux/filesystem/targetfs-images/targetfs.img
          $ sudo ln -s ${NV_WORKSPACE}/drive-linux/filesystem/targetfs-images/driveos-updated-rfs.img
          ${NV_WORKSPACE}/drive-linux/filesystem/targetfs-images/targetfs.img

       3. Flash the target using the SDK Bootburn tool.

depmod -a
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