On Tue, Oct 5, 2010 at 4:40 PM, Graeme Russ <[email protected]> wrote: > On Tue, Oct 5, 2010 at 4:34 PM, Wolfgang Denk <[email protected]> wrote: >> Dear Graeme Russ, >> >> In message <[email protected]> >> you wrote: >>> >>> Can NAND SPL initialise and size memory before loading U-Boot into RAM? >> >> It has to. You cannot load into and run from uninitialized RAM ;-) >> >>> If so, could the relocation code be added to NAND SPL so only one copy >>> operation is performed? >> >> I'm afraid it cannot, due to size limitations. The NAND loader often >> hast to fit into as little a 2 or 4 KiB... >> > > For x86, the actual relocation calculations can be done in a probably a > few dozen bytes of code. It contains: > > - One offset calculation > - A single tight loop > - Two comparisons (probably not needed in the generic case as they are used > to filter out x86 specific code outside .text) > - An offset addition > > If the only constraint is space then it _may_ be possible in some scenarios > (although I do acknowledge that previous trival changes have caused the > size constaint to be violated) >
Another alternative is to load into upper memory and have the relocation code detect that U-Boot is already there and skip the copy operation Regards, Graeme _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
