Gentoo on the Nvidia Tegra 250 Developer KitInstalling Gentoo in the Nvidia Tegra 250 is pretty simple if you're already a Gentoo user. You can either use a sufficiently sized SD card (>=2GB for ease) or an USB HDD. If you are familar with the Gentoo Linux installation process, there is not much different here. To be able to install Gentoo, you'll need the following:
3. Preparing to install your Nvidia Tegra Before we start the installation process, we need to build a kernel for the Nvidia Tegra and the utility to flash it to our board on our computer. The Nvidia Tegra comes without any Operating System on it. At the moment it uses the fastboot method for flashing a kernel in case of Linux(Windows CE/Android is another story). U-Boot works but for now we'll use the official method. For booting the Nvidia Tegra we need a kernel. In this document we'll use the kernel provided by Nvidia which is available on Nvidia's GIT server. For doing so we need dev-vcs/git on our system.
Now that we have the kernel source, we can build it. However since the Nvidia Tegra is an ARM device, we need to crosscompile the kernel to ARM. For doing so, on Gentoo we use sys-devel/crossdev, which provides us an easy way to create a cross-compiler. On other Linux distros, you can use the CodeSourcery toolchain.
Once we have our crosscompiler, we can crosscompile it finally. We'll use the default kernel config since it has all we need.
Once it gets built, we'll now have a kernel image on arch/arm/boot/zImage. Obtaining and building the fastboot loader The bootloader we'll use is the one that gets used for Android. This bootloader, fastboot, is available on the Android SDK
After accepting the license, the binary will extract a directory called tegra_froyo_20110207. In this directory you'll find the fastboot bootloader. You also need to copy the previously built zImage into that directory We'll enter into the new directory and download the following file which contains the partitions that will be created on the board's NAND.
Compile the fastboot utility on your PC For flashing a kernel into the board, we need the fastboot utility on our PC. The flashing is done through the miniUSB port the board has.
For building such tool, we need, unfortunately, java.
Then, we'll checkout the repositories that are needed for fastboot
Now, we compile it.
Now we'll format the NAND and flash the bootloader into it. Make sure you plug the power cable on the board, then connect the usb cable to the board and to your PC. To power on the board, you need to press *BOTH* the Force Recovery and the Power on buttons until the LEDs power up. Then execute the following command to flash the bootloader.
That means the flashing of the bootloader went correctly, we can now flash the kernel.
Remember to save this command(and the binaries), since its the command you'll need to put a new kernel That means our Nvidia Tegra is ready to boot, now you can turn it off, and let's focus on the Gentoo installation on our USB disk The installation this device is a bit different, as we can't install Gentoo on it by booting an installation environment. For installing Gentoo(and any other distro, really) you need to put the USB disk or usb stick on your PC and prepare there the minimal installation. I'd recommend reading the ARM handbook, for creating the partitions, extracting the stage, configure the networking, etc...until you're able to create a minimum filesystem. So please read and follow the ARM Handbook from the beginning, just skip the 10th chapter, as its irrelevant for our machine. I'll just explain what we have to do differently. Please read below first so you know when you have to go back to this document during the installation. Here's some information about the stages.
We'll be using the new EABI, also called gnueabi, instead of the old ABI. That is armel on Debian. There's no exact reason for why we should use this EABI and not the old one, apart that this one is better than the old. Therefore, we need an armv7a-unknown-linux-gnueabi stage3, available under the releases/arm/autobuilds directory in your favorite mirror
Edit the /mnt/hdd/etc/fstab file to look like this:
Setting the default root password This is the most important part of the installation. As without the root password we won't be able to login! For setting the password, we need to be able to run passwd. However that's not possible since our PC can't run ARM binaries. Therefore we need to modify the file that contains the passwords (/etc/shadow) inside the chroot, so we can set a default root password.
Please read the network configuration chapter of the ARM handbook to configure the network. Enabling SSH access (optional) We can add sshd to the startup of our system so we can access our Nvidia Tegra board using ssh.
Enabling serial console access (optional) By default the ttyS0 port is configured at 9600 bps. However, almost all of the ARM devices run the serial port at 115200 bps. So this should be added to the /etc/inittab file:
Once you've finished the installation of Gentoo into your Nvidia Tegra, you can simply push the reset button. Then it will boot from the external storage device. You may find more documentation about the device itself and Linux-related at the following links:
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