The Jetson Nano doesn't come with all the standard Linux kernel modules compiled in. You might want one that isn't there by default. For example, TTL mangling doesn't work on the Jetson Nano.
$ sudo iptables -t mangle -I POSTROUTING -j TTL --ttl-set 65 iptables: No chain/target/match by that name.
NVIDIA publishes a guide for compiling the kernel, but it's a bit opaque. Figuring out this process helped me understand a small chunk of the linux kernel module world, so I'd like to share a more didactic guide to compiling the kernel from scratch. If you notice any issues going through this guide, please feel free to email me or suggest an edit.
First, you'll need to be on an Ubuntu machine. The NVIDIA SDK doesn't allow execution under root, so it won't work with WSL sadly.
Download the
SDK Manager
and ship that .deb file over to your Ubuntu VM. Install the
dependencies, noting that the .deb file specified here needs
to match the one you received.
sudo apt install -y libgconf-2-4 libcanberra-gtk-module sudo dpkg -i sdkmanager_1.4.0-7363_amd64.deb
Run the SDK Manager to query available targets.
sdkmanager --cli --query interactive
Choose the options relevant to you, but skip flashing. My configuration with the Jetson Nano 2GB looks like
$ sdkmanager --cli --query interactive Waiting for user information from NVIDIA authentication server... Retrieving user information... Loading and processing available products... Login succeeded. Loading user information... User information loaded successfully. Loading server data... Server data loaded successfully. - select product: Jetson - hardware configuration: Target Hardware - select target: Jetson Nano modules - select target operating system: Linux - select version: JetPack 4.6.2 - get detailed options: No - flash the target board: No Launch Command: sdkmanager --cli install --logintype devzone --product Jetson --targetos Linux --version 4.6.2 --target JETSON_NANO_TARGETS --flash skip
Run that launch command that it spits out and go through the interactive process. This will take a while to download/install everything.
Now, we can follow the NVIDIA guide a little closer. We'll install the compilation toolchain, which includes gcc and all those goodies.
wget http://releases.linaro.org/components/toolchain/binaries/7.3-2018.05/aarch64-linux-gnu/gcc-linaro-7.3.1-2018.05-x86_64_aarch64-linux-gnu.tar.xz tar xf gcc-linaro-7.3.1-2018.05-x86_64_aarch64-linux-gnu.tar.xz export CROSS_COMPILE=$(pwd)/gcc-linaro-7.3.1-2018.05-x86_64_aarch64-linux-gnu/bin/aarch64-linux-gnu- export LOCALVERSION=-tegra
You can find the latest version of the source code on the NVIDIA downloads page under "L4T Sources".
wget https://developer.nvidia.com/embedded/l4t/r32_release_v7.1/sources/t210/public_sources.tbz2 tar -xjf public_sources.tbz2 cd Linux_for_Tegra/source/public tar -xjf kernel_src.tbz2 cd kernel/kernel-4.9
Make sure the proper dependencies are installed.
sudo apt install -y build-essential bc libncurses5 libncurses5-dev
and specify where the kernel output should go (you can choose a different location, it doesn't matter)
TEGRA_KERNEL_OUT=$HOME/t4l-kernel mkdir -p $TEGRA_KERNEL_OUT
Initialize the config
make ARCH=arm64 O=$TEGRA_KERNEL_OUT tegra_defconfig
Then configure the build. Choose the options you want. Alternatively, you
can specify the specific module by name by editing
$TEGRA_KERNEL_OUT/.config.
make ARCH=arm64 O=$TEGRA_KERNEL_OUT menuconfig
If you are specifically looking to enable TTL mangling, enable
CONFIG_NETFILTER_XT_TARGET_HL in
$TEGRA_KERNEL_OUT/.config.
After configuring, kick off the build, replacing 4 with the number of cores your system has.
make ARCH=arm64 O=$TEGRA_KERNEL_OUT -j4
The NVIDIA SDK manager should have created a directory at
~/nvidia/nvidia_sdk/JetPack_4.6.2_Linux_JETSON_NANO_TARGETS/Linux_for_Tegra
(or similar, depending on your board choice in the second step). Copy over
the Image and dtb files.
cp $TEGRA_KERNEL_OUT/arch/arm64/boot/Image ~/nvidia/nvidia_sdk/JetPack_4.6.2_Linux_JETSON_NANO_TARGETS/Linux_for_Tegra/kernel/Image cp -r $TEGRA_KERNEL_OUT/arch/arm64/boot/dts/* ~/nvidia/nvidia_sdk/JetPack_4.6.2_Linux_JETSON_NANO_TARGETS/Linux_for_Tegra/kernel/dtb
Then install the modules
sudo make ARCH=arm64 O=$TEGRA_KERNEL_OUT modules_install INSTALL_MOD_PATH=~/nvidia/nvidia_sdk/JetPack_4.6.2_Linux_JETSON_NANO_TARGETS/Linux_for_Tegra/rootfs/
Lastly, change over to this directory and build the sdcard image. Note
that the target for jetson-disk-image-creator.sh will change
depending on your board. Run
./tools/jetson-disk-image-creator.sh to get the options
available.
cd ~/nvidia/nvidia_sdk/JetPack_4.6.2_Linux_JETSON_NANO_TARGETS/Linux_for_Tegra/ sudo ./apply_binaries.sh -r rootfs sudo ./tools/jetson-disk-image-creator.sh -o sdcard.img -b jetson-nano -r 300
Take that sdcard.img and flash it with your favorite
sd card imager and we're off
to the races. For me, that means
sudo iptables -t mangle -I POSTROUTING -j TTL --ttl-set 65
works!
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