Build#

Compiling the Kernel (Canonical Kernel 6.8)#

You can compile the Linux kernel source in your Linux SDK product.

Set up the environment macros; the LOCAL_VERSION environment variable appends -rt-tegra to the kernel version and modules:

export NV_WORKSPACE=${PWD}
export ARCH=arm64
export CORE_KERNEL_DIR=canonical-6.8
export OUT_DIR=/tmp/${CORE_KERNEL_DIR}
export KERNEL_OUT_BUILD_DIR=${OUT_DIR}
export BUILD_CONFIG=prod_nsr # or test_nsr or dev_nsr
# for prod_nsr, test_nsr
export PROD_SUFFIX=_prod
# for dev_nsr
export PROD_SUFFIX=""

Compile Kernel

cd ${NV_WORKSPACE}/drive-linux/kernel

# Note:
# The "--update-sdk" option in the command below copies the newly built images and kernel modules into the default SDK paths.
# Before proceeding, ensure you back up the existing default kernel modules located at ${NV_WORKSPACE}/drive-linux/kernel/canonical-6.8/preempt_rt${PROD_SUFFIX}/modules/*
./compile_kernel.sh --nv-workspace ${NV_WORKSPACE} --core-kernel-dir ${CORE_KERNEL_DIR} --nv-build-config ${BUILD_CONFIG} --out-dir ${OUT_DIR} --update-sdk

Copy built modules to the root file system by rebuilding the filesystem based on <pct_variant> (which can be prod_nsr, test_nsr, or dev_nsr):
```
/drive/drive-linux/filesystem/create_linux_targetfs.sh -p <pct_variant>
```

Update initramfs with built modules:

# If Building a production kernel for prod_nsr/test_nsr PCTs, then please set:
export INITRAMFS_IMAGE=${NV_WORKSPACE}/drive-linux/filesystem/initramfs/prod-initramfs-canonical-6.8.cpio

# Else If building a standard kernel for dev_nsr PCT, please set:
export INITRAMFS_IMAGE=${NV_WORKSPACE}/drive-linux/filesystem/initramfs/initramfs-canonical-6.8.cpio

# Extract the initramfs.
cd ${NV_WORKSPACE}/drive-linux/filesystem/initramfs
mkdir -p tmp; cd tmp; cpio -imdu --quiet < ${INITRAMFS_IMAGE}

# Run copytarget to copy kernel modules.
export NVRTKERNELNAME=$(basename ${NV_WORKSPACE}/drive-linux/kernel/canonical-6.8/preempt_rt${PROD_SUFFIX}/modules/*rt*-tegra)
export NV_SDK_NAME_LINUX=drive-linux
# for prod_nsr, test_nsr
export INITRAMFS_FS_TYPE=prod_boot_initramfs
# for dev_nsr
export INITRAMFS_FS_TYPE=boot_initramfs
rm -rf lib/modules/*
${NV_WORKSPACE}/drive-common/filesystems/copytarget/1.4/copytarget.py $PWD ${NV_WORKSPACE}/ ${NV_WORKSPACE}/drive-linux/filesystem/copytarget/manifest/copytarget-initramfs.yaml --filesystem-type ${INITRAMFS_FS_TYPE}

# Create the depmod and alias
for k in $(ls -d ./lib/modules/*); do
  echo "Running depmod for kernel modules at $k"
  depmod -b . -a $(basename $k)
done

Rebuild updated initramfs:

find . | cpio --quiet -H newc -o > ${INITRAMFS_IMAGE}
cd ${NV_WORKSPACE}/drive-linux/filesystem/initramfs; rm -rf tmp

Run bind_partitions based on <pct_variant> (which can be prod_nsr, test_nsr, or dev_nsr):

cd /drive/drive-foundation
./make/bind_partitions -b <board name> drive_av.linux -p <pct_variant>

Flash the target to the board using the SDK bootburn tool.
Boot the board. The built kernel modules will auto-load on boot.