Compiling the Kernel (Kernel 5.15)

Set up the environment macros: The LOCAL_VERSION environment variable appends -rt-tegra to the kernel version and modules, please ensure $NV_WORKSPACE is set to <top> of the PDK install directory.

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

Set the kernel source directory as the current working directory:

cd $NV_WORKSPACE/drive-linux/kernel/source/oss_src

Enter the following command to apply the rt-patches.

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

sudo apt-get update
sudo apt-get -f -y install imagemagick graphviz dvipng python3-venv fonts-noto-cjk latexmk librsvg2-bin texlive-xetex flex bison

Create an output directory and clean up.

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

Configure the kernel to the standard kernel with the command. To build a production kernel instead of a standard kernel, please use tegra_prod_defconfig instead of defconfig.

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

Build the kernel:

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

ln -s -f ${PWD}/nvidia-oot /tmp/nv-oot
make -j3 -C ${PWD}/out-linux M=/tmp/nv-oot srctree.nvidia-oot=/tmp/nv-oot srctree.nvidia=/tmp/nv-oot V=1 modules CONFIG_TEGRA_OOT_MODULE=m

export INSTALL_MOD_PATH=${PWD}/out-linux
make -C kernel O=${PWD}/out-linux modules_install
make -C ${PWD}/out-linux M=/tmp/nv-oot modules_install
rm /tmp/nv-oot

1. Unify headers and Module.symvers for display module compilation:

   cd $NV_WORKSPACE/drive-linux/kernel/source/oss_src
   cat nvidia-oot/Module.symvers >> out-linux/Module.symvers
   rsync -avzpq nvidia-oot/include/ out-linux/include
   rsync -avzpq nvidia-oot/drivers/gpu/host1x/include/ out-linux/drivers/gpu/host1x/include

2. Untar the display source code.

   The NVIDIA-kernel-module-source-<Version>.tar.xz source code is supplied as a .xz file. Untar the file. Its location is <NV_WORKSPACE>/drive-linux_src/

   tar -xvf $NV_WORKSPACE/drive-linux_src/NVIDIA-kernel-module-source-TempVersion.tar.xz

3. Compile the display kernel module.

   export IGNORE_PREEMPT_RT_PRESENCE=1
   cd NVIDIA-kernel-module-source-TempVersion
   make \
       modules \
       SYSSRC=$NV_WORKSPACE/drive-linux/kernel/source/oss_src/kernel \
       SYSOUT=$NV_WORKSPACE/drive-linux/kernel/source/oss_src/out-linux \
       SYSSRCHOST1X=$NV_WORKSPACE/drive-linux/kernel/source/oss_src/nvidia-oot/drivers/gpu/host1x/include\
       CC=${CROSS_COMPILE}gcc \
       LD=${CROSS_COMPILE}ld.bfd \
       AR=${CROSS_COMPILE}ar \
       CXX=${CROSS_COMPILE}g++ \
       OBJCOPY=${CROSS_COMPILE}objcopy \
       TARGET_ARCH=aarch64 \
       ARCH=arm64

4. Copy the display modules to the module_install path.

   mkdir -p $NV_WORKSPACE/drive-linux/kernel/preempt_rt${PROD_SUFFIX}/modules/<kernel_version>extra/opensrc-disp/
   cd kernel-open
   cp nvidia.ko nvidia-modeset.ko nvidia-drm.ko $NV_WORKSPACE/drive-linux/kernel/preempt_rt${PROD_SUFFIX}/modules/<kernel_version>extra/opensrc-disp/

1. Copy the uncompressed (Image) kernel images to the top of the kernel directory with the following command:

   export PROD_SUFFIX=<str> # If using production kernel, set <str> to "_prod" else set to empty string ""
   sudo rm -fv $NV_WORKSPACE/drive-linux/kernel/preempt_rt${PROD_SUFFIX}/images/*
   sudo cp -v ${PWD}/out-linux/arch/arm64/boot/Image ${PWD}/out-linux/vmlinux ${PWD}/out-linux/System.map $NV_WORKSPACE/drive-linux/kernel/preempt_rt${PROD_SUFFIX}/images/

   CAUTION: Before copying the new kernel images, please back up the default kernels provided.
2. Copy the built modules to the SDK kernel modules path:

   sudo rm -rf $NV_WORKSPACE/drive-linux/kernel/preempt_rt${PROD_SUFFIX}/modules/*
   sudo cp -a ${PWD}/out-linux/lib/modules/* $NV_WORKSPACE/drive-linux/kernel/preempt_rt${PROD_SUFFIX}/modules/

3. Copy the built modules to the root file system path with the following commands:
   1. 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 using the editor of your choice. Name it update_rfs.CONFIG.json and put it in $PWD. The parameter <fstype> should be standard, production, production_debug depending on the list of modules to be copied to the filesystem.

         {
             "OS": "linux",
             "Output": "driveos-updated-rfs",
             "Base": "${BASE_DIR}/targetfs.img",
             "FilesystemType": "<fstype>",
             "CopyTargets": [
                 "${COPYTARGETYAML_DIR}/copytarget-kernel-modules.yaml"
             ],
             "PostInstalls": {
                 "/etc/nvidia/run-once/nv-run-once-run-ldconfig": "target",
                 "/etc/nvidia/run-once/nv-run-once-run-depmod": "target"
             }
         }

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

         export NVRTKERNELNAME="$(basename $NV_WORKSPACE/drive-linux/kernel/preempt_rt${PROD_SUFFIX}/modules/*rt*-tegra)"
         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.img
         sudo ln -s ${NV_WORKSPACE}/drive-linux/filesystem/targetfs-images/driveos-updated-rfs.img ${NV_WORKSPACE}/drive-linux/filesystem/targetfs.img

1. If Building a production kernel, then please set

   1. export INITRAMFS_IMAGE=$NV_WORKSPACE/drive-linux/filesystem/prod-initramfs.cpio

2. Else If building a standard kernel, please set

   1. export INITRAMFS_IMAGE=$NV_WORKSPACE/drive-linux/filesystem/initramfs.cpio

3. Extract the initramfs.

   1. sudo rm -rf ./initramfs; sudo mkdir -p ./initramfs; cd
                        ./initramfs

   2. sudo cpio -imdu --quiet < ${INITRAMFS_IMAGE}
4. Run copytarget to copy kernel modules.

       export PROD_SUFFIX=<str> # If using production kernel, please set <str> to "_prod" else set to empty string ""
       export NVRTKERNELNAME="$(basename $NV_WORKSPACE/drive-linux/kernel/preempt_rt${PROD_SUFFIX}/modules/*rt*-tegra)"
       export NV_SDK_NAME_LINUX=drive-linux
       sudo rm -rf lib/modules/*
       sudo -E /opt/nvidia/driveos/common/filesystems/copytarget/1/copytarget.py $PWD $NV_WORKSPACE/ $NV_WORKSPACE/drive-linux/filesystem/copytarget/manifest/copytarget-kernel-modules.yaml --filesystem-type boot_initramfs

5. Re-create updated initramfs:

   1. sudo find . | sudo cpio --quiet -H newc -o >
                  ${INITRAMFS_IMAGE}