A RAW partition is any partition on the eMMC that is not formatted. BootROM and PLM supports SD/eMMC in RAW format in addition to the existing file system mode support.
The BootROM searches for the boot image and finds it on the file system or in RAW. After the image is found, the BootROM updates the Multiboot register with the image information. The PLM continues the boot from the file system or RAW with the information from the MultiBoot register.
The MultiBoot register contains information such as whether the image is from the file system or RAW, image file number or the offset.