Getting Started for Development

When a Jetson board is connected using USB, a USB-OTG network interface is created and assigned the address of 192.168.55.1.

Setting up to copy files from host to target

The build scripts utilize ssh and rsync to efficiently copy files to the development board.

Set up ssh

The BSP scripts connect to the Jetson board using a dedicated SSH keypair. This keypair will be used whenever files are copied or when you create a remote shell. With this configuration, you do not have to specify the nvidia username or password every time you ssh to the board.

Run the following commands on the host:

• Create a keypair: ssh-keygen -t rsa -b 4096 -C '[email protected]'

  • When prompted, save the keypair into ~/.ssh/nvidia

• If the SSH agent isn't already running, eval "$(ssh-agent -s)" to start it.

• Add the keypair to the ssh agent: ssh-add ~/.ssh/nvidia

• Edit ~/.ssh/config to contain the following:

   Host 192.168.55.1
   User nvidia
   IdentityFile ~/.ssh/nvidia
   StrictHostKeyChecking no
   UserKnownHostsFile /dev/null
  

  This config snippet disables strict host checking and does not record to the known-hosts list. This is done to avoid having to edit the known-hosts file. This would be very bad practice ordinarily but is OK for development boards.

• Make sure the target is connected to USB and has booted up.

• Copy the ssh key to the target board: ssh-copy-id -i ~/.ssh/nvidia [email protected]

• Test that it worked: run ssh 192.168.55.1 whoami. You should see the response nvidia.

• Optional, but recommended steps:

  • Make sure the target is connected to the network. Run ping 8.8.8.8.
  • Install useful packages: run

   sudo apt-get install ack build-essential cmake libexpat1-dev libgstreamer1.0-dev libgtk-3-dev libjpeg-dev libx11-dev mplayer pkg-config silversearcher-ag strace tree vlc
  

Set up OS support on the target

Make sure the target is connected to USB and has booted up. Then, on the host, run bin/prep-new-system-from-host. This will:

• Update OS packages
• Install required packages (such as rsync)
• Update /etc/sudoers to permit ssh 192.168.55.1 sudo ... invocations
• Turn off screen lock
• Copy helper scripts from ./debug on the host to ~/nvidia/debug on the target

This also creates a backup of the default Nvidia kernel, which may be useful to you if you happen to "brick" your system.

NOTE: Only run bin/prep-new-system-from-host once on any particular board. At present, a subsequent run will overwrite the backup of the default kernel with the latest kernel, whatever that may be.

Set up development environment

The BSP uses an Automake configure-based workflow. The configure script is generated by the provided bootstrap script. Do the following on the host:

• Create the configure script: ./bootstrap.

• Run the configure script: ./configure [options]. For example, to configure the build for a Xavier board using an Imx390rcm camera via a D3 16-port "2xOcto" camera interface, run:

   ./configure --with-system-type=xavier --with-dtb='build/deploy/boot/d3-xavier-2xocto-imx390rcm.dtb'
  

  You may specify any of the following options:

  • --with-system-type: tx2, xavier, or nano. This defaults to tx2 and influences other defaults like the --with-l4t option.

  • --with-l4t: Specify an alternate Linux for Tegra (L4T) host directory if you did not use the defaults from Nvidia's SDK Manager (~/nvidia/nvidia_sdk as of writing). This will default to the SDK Manager install path for the given system-type.

  • --with-dtb: Specify a dtb file path for the target hardware configuration

Build the kernel and device tree

On the host:

• Configure the kernel: make linux-defconfig (or make linux-menuconfig if you want to tweak the configuration)
• Build the kernel and device tree binary (DTB) files: make -j8. For verbose output, add KBUILD_VERBOSE=1.
  • NOTE: Every time you run make with the default target, a new "build ID" will be generated. This is a UUID specific to that run of make. Therefore, whenever you run make, at least the ID will change, and the kernel proper will be recompiled to include it.

At the end of a successful make, you will see the build ID. You can also see the build ID of the most recent build by running make show-config.

Update the target with the new kernel and device tree

On the host:

• Copy: make sync. This will copy/flash the kernel, modules, and DTB to the target. For verbose output, add V=1.
• Reboot: make reboot

After rebooting, make sure it worked. On the host, ssh 192.168.55.1. Then, on the target:

• Check the kernel's compiled-in build ID: cat /sys/module/build_id/version. It should match the build ID you saw when running the steps above.
• Check the device tree's compiled-in build ID: cat /proc/device-tree/d3,jetson-bsp-build-id ; echo. It should also match.

Recovering

This section is under construction

If you are not able to run the normal make sync, you can recover the target.

First, place the target into recovery mode:

• Unplug power, then plug it back in.
• Make sure the USB micro-B is plugged in.
• Press the PWR button
• While holding the REC button, press and HOLD the RST button for two seconds
• Release the RST button, then wait two seconds
• Release the REC button

Then, from the host:

• Update the kernel (Xavier only): make flash-kernel
• Update the DTB: make flash-dtb