On Sep 11, 2009, at 1:02 PM, Kumar Gala wrote: > From: Mingkai Hu <mingkai...@freescale.com> > > The MPC8536E is capable of booting form NAND/eSDHC/eSPI, this patch > implements these three bootup methods in a unified way - all of these > use the general cpu/mpc85xx/start.S, and load the main image to L2SRAM > which lets us use the SPD to initialize the SDRAM. > > For all three bootup methods, the bootup process can be divided into > two > stages: the first stage will initialize the corresponding controller, > configure the L2SRAM, then copy the second stage image to L2SRAM and > jump to it. The second stage image is just like the general U-Boot > image > to configure all the hardware and boot up to U-Boot command line. > > When boot from NAND, the eLBC controller will first load the first > stage > image to internal 4K RAM buffer because it's also stored on the NAND > flash. The first stage image, also call 4K NADN loader, will > initialize > the L2SRAM, load the second stage image to L2SRAM and jump to it. > The 4K > NAND loader's code comes from the corresponding nand_spl directory, > along > with the code twisted by CONFIG_NAND_SPL. > > When boot from eSDHC/eSPI, there's no such a first stage image because > the CPU ROM code does the same work. It will initialize the L2SRAM > according to the config addr/word pairs on the fixed address and > initialize the eSDHC/eSPI controller, then load the second stage image > to L2SRAM and jump to it. > > The macro CONFIG_SYS_RAMBOOT is used to control the code to produce > the > second stage image for all different bootup methods. It's set in the > board config file when one of the bootup methods above is selected. > > Signed-off-by: Mingkai Hu <mingkai...@freescale.com> > Signed-off-by: Kumar Gala <ga...@kernel.crashing.org> > --- > * Merged in changes from other patch into u-boot-nand.lds > * Fixed up and simplified tlb.c changes > > - k
applied to 85xx - k _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot