On Wed, Sep 30, 2015 at 10:56:20AM -0700, Andrey Smirnov wrote: > >> I'd still like to discuss the possibility of introducing a feature > >> like that to the codebase. Right now I have a use-case where I use > >> Barebox as a DDR memory tuning/testing tool on i.MX6Q where I upload > >> the image to IRAM via JTAG and execute Barebox straight out of SRAM. > > > > I understand your usecase and I think it's worth supporting it. > > > > So what are our options? You could run the tuning/testing completely > > from the PBL. We now have console support in the PBL, so you can output > > the results. You cannot do any interactive things though. We could add > > simple getc() support to the PBL, but something like a shell is out of > > reach. Do you need interactive input anyway? > > Another possibility would be to make device tree support optional for > > i.MX6. It is optional for the other i.MXes for historic reasons, so we > > could make it optional for i.MX6 aswell. This would give you another > > ~30K which is now used by the dtb. > > I'm a bit afraid that the regular-barebox-in-SRAM usecase will break > > quite frequently upstream because the image gets too big or simply > > because some other changes have side effects. For this reason I would > > really prefer the PBL way if that's possible for you. > > > > Oh, I don't think I mentioned in my previous e-mail, but I do have a > working Barebox image for that case. The way I have it implemented > right now is a vanilla, single board, no-PBL, no-relocation, i.MX6Q > SabreSD Barebox image with a minimal configuration. The only things I > had to change was device tree file -- default required to much RAM to > instantiate, so I had to trim it down -- and this patch to avoid > copying FTD that is already built-in. Oh, and I also had to disable > MMU, because page table takes about 1MB or RAM(I haven't had a chance > to spend any time trying to modify MMU code to support coarser > 1MB-page page table). > > The image is intended to be used by EEs to do DRAM related > experiments, so I do need a shell and that was the reason I went with > full Barebox instead of trying to cram it in PBL. Ok, I see. I think your original patch is almost fine, only the test if you need to copy or not needs adjustment. You have to test if the fdt is membase < dtb < membase + memsize. If it is you have to copy it, otherwise it should be fine to use it in place. Would that work? Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
