The bootstrap loader or boot loader is a small program running on a computer or device after power-on to load the operating system. Most boot loaders today provide additional features that allow to upgrade the firmware and access the system for troubleshooting. Although Xtensa kernel can be compiled with a reset vector included in the kernel image, thus omitting a boot loader, this option is usually not used.
The kernel build scripts always create a bootable ELF-image for Xtensa. It includes a Reset handler and can directly be downloaded to the target.
Tensilica has done a port of RedBoot for the Xtensa architecture. For more information and to request sources, please, contact Tensilica directly.