Fastboot

uboot

MMC Partitioning Explained

MultiBoot based on KexecBoot

swarren_brain_dump explains a lot about how the device boots from eMMC

This explanation is based on http://www.muromec.org.ua/2011/03/blog-post.html

• After power-on, a ROM bootloader (RCM?) integrated in Tegra2 IC starts
• If Ctrl-Esc is pressed (most probably detected via a dedicated line between EC and Tegra), the loader switches to “nvflash” mode (USB 0x0955:0x7820) and starts to receive commands on its mini-USB receptable, putusb and nvflash are the tools that can communicate with it in this mode.
• If the boot is to continue, the bootloader assess some fuse bits settings to see where it should boot from, on ac100 that's internal eMMC.
• It searches for BCT (Boot Config Table) and for PT (Partition Table) on the eMMC and finds EBT (4th) partition there
• Vendors supplies EBT with Fastboot bootloader which then reads an image (in abootimg format) from the LNX (6th) (or if the “Home” button is pressed SOS (5th)) partition, copies the kernel and initramfs to the approprieate RAM locations and starts it supplying default command line parameters (with ATAGs).