Compiling Jetson TX1/TX2 source code: Difference between revisions

<seo title="Compiling Tegra Source Code | Jetson Tegra X1 and X2 | RidgeRun" titlemode="replace" keywords="GStreamer, Linux SDK, Linux BSP,  Embedded Linux, Device Drivers, Nvidia, Xilinx, TI, NXP, Freescale, Embedded Linux driver development, Linux Software development, Embedded Linux SDK, Embedded Linux Application development, GStreamer Multimedia Framework,Compiling Jetson,Jetson TX1/TX2 source code,Tegra source code ."  description="Learn about compiling Tegra source code for Jetson TX1 and TX2. Read related articles and instructions for Jetpack online now at RidgeRun Developer."></seo>

In this wiki page you are going to find the instructions to download the source code to rebuild the Jetson TX1/TX2 images using jetpack, several parts of this wiki were based in the document called Start_L4T_Docs.html given by Nvidia in L4T. This page should be considered a work in progress. These steps were run on Jetson Tegra X1 and Tegra X2 and Jetpack 3.2.1 was used. Additionally, in section [[Compiling_Jetson_TX1/TX2_source_code#Articles_related|Articles Related]] you can find instructions on how to build using older versions of Jetpack.

It is assumed that the reader already read [https://developer.ridgerun.com/wiki/index.php?title=Tegra_X1#Tegra_X1 the brief Jetson TX1 introduction]

In order to be able to download the source code you should have Jetpack  installed, if you already have it, skip the next section and go to [[Compiling_Jetson_TX1/TX2_source_code#Getting_bootloader_and_kernel|Getting bootloader and kernel]].

1. You can download the official NVIDIA toolchain for JetPack 3.2.1:

'''5.''' Follow the instructions. You'll be prompted for a devkit to build for (TX1, TX2, TX2i) just select the one you want.

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'''1.1 RECOMMENDED'''  

When syncing, you'll be asked for a tag, lets use '''tegra-l4t-r28.2.1''' for both Kernel and uboot.

In order to compile the kernel please follow these steps

1) Make sure you have the kernel source code and the toolchain already installed by following the instructions in these sections:

As an important note, kernel will be located not in a partition but in /boot on the filesystem this make easier a kernel update.

A USB cable is required and must be connected to the recovery port prior to running the flashing command.<br><br>

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In previous versions of jetpack, updating the DTB was as easy as replacing the one in the boot folder of the boot directory and you could also just change the FDT entry in '''/boot/extlinux/extlinux.conf''' to use a different one. For Jetpack 3.1 this was changed and a separate partition is used to flash the DTB file and Nvidia says you can only update it by flashing it again using the provided '''flash''' script.  

'''NOTE:''' Use mmcblk1p1 for SDcard and mmcblk0p1 for emmc.

You'll need to generate signed/encrypted dtb files through the flash scripts and then flash it to the kernel-dtb partition of the Jetson device.

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The bootloader is a combination of NVIDIA T-Boot (nvtboot) and U-Boot. You can read about the BOOT FLOW in the [http://http.download.nvidia.com/tegra-public-appnotes/t210-nvtboot-flow.html nvtboot wiki page].  

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1. Backup original uboot files. You see which platform you are using checking the file in $DEVDIR/jetson-tx1.conf, it says:

If you are attached to the serial port while flashing you should see the [http://developer.ridgerun.com/wiki/index.php?title=Jetson_TX1_serial_port_output serial port output log while flashing]

According to the U-boot guide provided by Nvidia uboot scans booteable devices as follows:

extlinux.conf is a standard text-format sysboot configuration file that contains all boot information, it is installed in /boot according to the boot method.

Following [http://developer.ridgerun.com/wiki/index.php?title=Jetson_TX1_Boot_Log boot log] was obtained when connected to the serial console using the [http://developer.ridgerun.com/wiki/index.php?title=Jetson_TX1_uboot_environment default uboot environment].

The environment is defined in extlinux.conf, however, the environment variables can be set in the uboot code directly or directly when the board is booting using the typical uboot commands like: print, saveenv, printenv, etc

Jetpack comes with a sample filesystem with X and ubuntu and Canonical keeps updating the packages available, you can also use your own filesystem. In both cases you have to install on it the Nvidia binaries, the instructions to do that are in the file Start_L4T_Docs.html, in the Getting started section. It mentions:

The remaining steps on this guide assumes that you are using the default filesytem or that you already have one built, specially for the flashing section, where flashing assumes that the filesystem already exists.

1. Locate and edit the following file:

  $ sudo apt-get install wget

Nvidia provides several scripts to help to generate the images and to flash the resulting images. Including if you are going to install uboot or fastboot. First the board needs to be in recovery mode and then the main script to flash it is $DEVDIR/Linux_for_Tegra_tx1/flash.sh. What this script will do is to install or flash the image in the desired destination. It is important that the script is controlled by variables defined in the DTB file.

There is a [http://jetsonhacks.com/2015/12/01/serial-console-nvidia-jetson-tx1/ nice video with details].

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:[[Compiling_Tegra_source_code_-_Jetpack_3.1 | Compiling with Jetpack 3.1]]