Hello - I am re-posting this question from about eight weeks ago, so that I am absolutely clear on the process.
Target device is an OMAP-L138 LCDK (with D800K008 boot ROM, silicon revision 2.1), capable of SD/MMC boot.
Development environment is Ubuntu 10.04.4 LTS (Lucid Lynx) using the ti-sdk-omapl138-lcdk-xx distribution + Windows 7 x86 SP1 using the TI StarterWare tools.
I would like to boot Linux entirely off the SD/MMC card–in this case, a 4GB micro SD. The intention is to decouple the device from the necessity of an on-board SPI or NAND flash–the SD card shall be fully field-replaceable and contain the boot loader / kernel / root filesystem.
I have read the wiki article and understand that there must be 3 separate "partitions", unformatted (AIS-signed U-boot binary) + FAT32 (kernel) + ext3 (root filesystem). I also understand the role of the AISgen utility to set up the pinmux / PLLs / clocks etc.
That said, the resources provided with the LCDK are not very concise (let's ignore the various setup script issues for now) as regards a vanilla SD boot configuration. The create-sdcard.sh script provided in $TI_SDK_PATH/bin/ is not designed to accomodate a multi-partition overlay for this application.
So–here's what's happened...I somehow managed to get this to work. Once. Since then, for whatever reason(s), I cannot seem to get the LCDK to fully boot off SD card (boot loader + kernel + root filesystem) unless I use the Serial Flash Utility (omapl138_sfl.exe?) to load U-Boot into NAND flash and load the kernel and root filesystem as per usual (as supplied from the factory).
I'm aware of the issues regarding the master boot record on the SD card, and aware of the fact that simply using the dd command to image the (AISgen-signed) boot loader binary onto the front of the SD card will not work without an offset.
What is the easiest and most straightforward way to do this, as it seems I'm missing something patently obvious here? Magic-word signing (0x41504954)? Pinmux? Is there a default overlay for AISgen that works (consistently) for SD/MMC boot?