Some terminology and tool information may be of use. Each Jetson arrives with “Linux for Tegra”…this is just Ubuntu with NVIDIA hardware accelerated drivers on top of it. The sample rootfs is purely Ubuntu, the proprietary hardware accelerated files are separate and are either added during flash or by the end user through the installer you mentioned. Any documentation on Ubuntu is perfectly valid even when the o/s is called “L4T”.
The L4T version a TX2 ships with would be R27.0.1 (unless something has changed which I’m not aware of). Currently L4T R28.1 is available. You can see the L4T release version with:
head -n 1 /etc/nv_tegra_release
For the current L4T see:
https://developer.nvidia.com/embedded/linux-tegra
You can validate if the hardware accelerated drivers are correctly in place via:
sha1sum -c /etc/nv_tegra_release
Since no Ubuntu system ships with all of the options installed it is normal and customary that the end user be the one to install those options (e.g., what if CUDA samples were added to every Ubuntu distribution? Or if OpenCV were installed by default on every desktop PC?). On a PC you have far more disk space, and you will find all kinds of driver modules and other software installed which would never be added to an embedded system. Despite a Jetson being as powerful as some desktop PCs it really is an embedded device with limited resources. You have the usual array of Ubuntu packages through the apt/dpkg package manager tools, but software specific to the embedded Jetson which is specific to NVIDIA hardware is handled through JetPack.
Flashing a Jetson is done through the driver package plus sample rootfs after the command for putting NVIDIA-specific drivers onto the sample rootfs is complete. This works with any x86_64 Linux desktop PC. JetPack is a front end to this flash software, and then adds all kinds of extra package management in addition to flashing. You don’t need to flash to use JetPack to manage packages. If you do use JetPack, then the PC should run Ubuntu 14.04 or 16.04 (only 14.04 is officially supported…JetPack also puts cross platform development tools on the PC host and some of those packages don’t work on 16.04…many do work on 16.04).
Flashing is done over the micro-B USB cable provided with the dev kit. Package management is done over the wired ethernet (don’t use WiFi). The two steps are independent. You could flash on command line with driver package plus sample rootfs and then manage packages with JetPack if you like.
It is highly unlikely you will be satisfied with the original R27.0.1 L4T. The current L4T release version is R28.1. R28.1 is the first release which has a common unified sample rootfs for both the TX1 and TX2. JetPack can work with both (currently JetPack version is at 3.1). You will find this same JetPack front end is valid for TX1 and TX2. The correct software is downloaded when needed after checking options.
Should you choose to flash (and I highly recommend doing so) you’ll want plenty of disk space on the PC host…perhaps 35GB or 40GB after JetPack and/or the driver package+sample rootfs are installed to the host. I also suggest just flash first, then reboot and restart and only then tell JetPack to add packages…uncheck flashing and do only package management. This should have example code for both host and Jetson and includes some cross compile software on the PC.