SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The contents of an eMMC or SD card may be formatted as raw binary (referred to as Raw(UDA) or within a FAT file system. The ROM Code reads out sectors from raw image or the booting file within the file system and boots from it.
In Raw(UDA) mode, an image can be at one of the four consecutive locations in the main area: offset 0x0 (0 KiB)/0x20000 (128 KiB)/0x40000 (256 KiB)/0x60000 (384 KiB). For this reason, the size of a booting image must not exceed 128 KiB. However, a device with an image greater than 128 KiB can be flash starting at one of the aforementioned locations. Therefore, the ROM code does not check the image size. The only drawback is that the image crosses the subsequent image boundary. Raw mode is detected by reading sectors 0, 256, 512, and 768. The content of these sectors is verified for the presence of a TOC structure. GP header must be located at the beginning of the booting image, as described in Section 32.3.8.2, Configuration Header . Image data is read directly from continuous sectors of a card. If raw mode is not detected, file system mode is assumed.
The read sector procedure uses the standard SD/eMMC read data procedure. The sector address is generated based on the booting memory file map collected during initialization. Thus, the ROM code can freely address sectors in the booting file space.