Hello Wolfgang, On Mon, Jun 20, 2011 at 3:46 PM, Wolfgang Denk <w...@denx.de> wrote: > Dear Christian Riesch, > > In message <1308575272-30559-1-git-send-email-christian.rie...@omicron.at> > you wrote: >> >> On this board, older versions of u-boot (like v2009.11) boot perfectly, >> even when TI's UBL boot loader is not used (instead the configuration of >> DDR memory was done using an AIS script). However, since commit > > What is AIS ?
I apologize for using that many abbreviations in my mail and not explaining them :-/ AIS is short for Application Image Script [1]. It is a boot script that is processed by the ROM bootloader on Texas Instrument's AM1808/DA850/OMAP-L138 processors. The script allows configuration of boot modes, PLLs, DDR memory, Pinmuxes etc and loading the an application like u-boot from flash to RAM and executing it. Using a suitable AIS one can configure PLL and DDR memory and then directly start u-boot on these processors, without using Texas Instruments's user boot loader (UBL) [2]. In the default configuration of the da850evm the boot sequence is like this: 1) ROM bootloader (RBL): starts reading from flash 2) In the SPI-flash, a very simple AIS is present. This AIS tells the RBL to load the UBL from flash and to start it. 3) The UBL does a lot of hardware initialization and then loads u-boot from flash and starts it. 4) u-boot does a lot of hardware initialization that has already been done by the UBL and then loads the Linux kernel. For my application I would like to get rid of the UBL since most of the configuration it does is also done by u-boot (although there seems to be a bug in it) or can be done by AIS (like PLL and DDR memory configuration), the resulting boot sequence will be: 1) ROM bootloader (RBL): starts reading from flash 2) In the SPI-flash, an AIS is present. This AIS tells the RBL to configure PLLs and DDR memory and to load u-boot from flash and to start it. 3) u-boot loads the Linux kernel. Hope that helps :-) Best regards, Christian [1] Using the AM18xx Bootloader (Rev. A) http://focus.ti.com/dsp/docs/litabsmultiplefilelist.tsp?sectionId=3&tabId=409&literatureNumber=spraba5a&docCategoryId=1&familyId=1877 [2] https://sourceforge.net/projects/dvflashutils/files _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
