-
Notifications
You must be signed in to change notification settings - Fork 242
Using cboot as bootloader
[Applicable to L4T R32.1.0 and later]
For Jetson AGX Xavier, NVIDIA provides only cboot as the bootloader, so there is no U-Boot recipe for that platform. For Jetson TX2, the default configuration uses both - cboot loads U-Boot, which then loads the Linux kernel. You can, however, use just cboot as the bootloader by setting
PREFERRED_PROVIDER_virtual/bootloader = "cboot-prebuilt"
in your build configuration. If you do this, cboot directly loads the Linux kernel and initial ramdisk from the LNX partition, and the kernel image is not added to the root filesystem.
Note that in L4T R32.2.x, cboot has issues if the kernel or the initrd is too large, at least on TX2 platforms, causing kernel panics at boot time. With L4T R32.3.1, the kernel size limitation appears to be resolved, but if you use a separate initrd (instead of building it into the kernel as an initramfs), there is still a limit of just a few megabytes on its size. If you plan to customize your kernel to build in more drivers, rather than leaving them as loadable modules, or if you need to build more functionality into your initial ram filesystem, use R32.3.1 and bundle the initramfs into your kernel.
NVIDIA has, from time to time, made cboot source code available. For Jetson AGX Xavier platforms, the most recent source release was with L4T R32.2.3, published in the L4T public_sources archive. This copy of cboot was removed from L4T R32.3.1. For L4T R32.4.2, cboot sources have been published again (for Xavier platforms only) as a separate download.
Older releases (R28.x for TX2, R31.1 for Xavier) were restricted downloads. You must use your Developer Network login credentials to download the source package from the appropriate L4T page on NVIDIA's website and store that tarball on your build host. The NVIDIA_DEVNET_MIRROR variable is used to locate the sources; see the recipes for more details on naming.
To use cboot built from source in your build, set
PREFERRED_PROVIDER_virtual/bootloader = "cboot"