> > To make things simple for users, there's standard layout. It's actually > > at sector 2048 btw. > > Got that. > > > That's what happens internally, it's just that some pieces (like sector > > offset of the partition!) need to be filled into the bootstream header > > by the mxsboot utility -- see mxsboot -h for how to change that. > > You're completely right! This sector needs to be know build-time because it > is specified in the Boot Stream Block of the Boot Stream header. I forgot > about that, because I hid that in a script some time ago. That script was > basically a rewritten version of the broken one that was supplied with the > SDK. > > Come to think of it, it's a bit weird that the sector the BSB is located > in, is specified in the BSB: When reading it, it already knows this > sector, because that's the sector it is reading from at that moment... > > > The 2048 sector offset was chosen because that's standard in Linux now > > for first partiiton. > > Agreed. > > > What do you mean? > > What I meant to ask was how you solved the paradoxic problem that U-Boot > needs to initialize SD-RAM before it can be loaded (and obviously U-Boot > needs to be loaded before it can initialize SD-RAM).
Well we have U-Boot SPL, which is loaded into SRAM, inits DRAM, pinmux etc., then we pass execution back to BootROM to load U-Boot into DRAM and execute it. > > Freescale solved this problem by putting multiple bootlets in their > bootstream. The first one is small enough to fit SRAM and it enables the > PMIC's LDOs to power up all power domains. The second one too is small > enough to fit SRAM. Loading it overwrites the first one and running it > initializes SD-RAM. The third one is either U-Boot or a Kernel and is > directly loaded into the now initialized SD-RAM. Yea, you can load kernel directly via U-Boot SPL too. > > I figured that your solution links U-Boot in a clever way that the lower > part fitting SRAM will initialize the PMIC and SD-RAM, after which U-Boot > will load the remainder of itself from MMC into SD-RAM. See above. > > > You can adjust that, see above. > > Understood. > > Cheers, > > Robert. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
