On Wed, 20 Jul 2016, Mario Six wrote: > On Wed, Jul 20, 2016 at 3:56 PM, Robert P. J. Day <rpj...@crashcourse.ca> > wrote:
... snip ... > > not really, since i always thought that the difficulty in loading > > and booting a second-stage u-boot was explained here: > > > > http://www.denx.de/wiki/view/DULG/CanUBootBeConfiguredSuchThatItCanBeStartedInRAM > > > > that is, loading the second image to a different address is simple; > > the apparent difficulty is that the second-stage u-boot might not be > > able to handle the early setup already done by the first stage. > > > > so i'm still confused as to what is being proposed here, and how it > > works. > > > > rday > > > > Ah, alright. Look at the following quote from the page: > > "On machines with boot-ROM and U-Boot-SPL, you might have better luck." > > I'd venture that most SoCs these days have a boot-ROM; on these > U-Boot, is not as sensitive to not finding a "virgin" system > (because the boot-ROM does some initialization beforehand). The > system I tested with is a Armada 38x, and we've also use a similar > approach on a MPC85xx system (if you would like to dig that deep, > the code is upstream: board/gdsys/p1022/controlcenterd*). The whole > SPL concept would be a problem if the boot loader needed a virgin > CPU (since, well, the SPL *is* a second U-Boot), so the restrictions > mentioned in the page are not as relevant for modern SoCs. > > That's as far as my knowledge goes, if anyone wants to correct me, > you're welcome to do so :-) ok, so it appears that wiki page is a little on the pessimistic side, then. i was aware of the SPL, having worked with beaglebone black for a while. i've never looked *closely* at how limited or restrictive the SPL is, but i did know it had to do far less than the full-featured u-boot. maybe it's time to look into that far more closely to understand it better, and to appreciate what's possible. i can see this 2013 presentation, "TPL: SPL loading SPL (and, SPL as just another U-Boot config", from scott wood of freescale. that looks like it might be educational. rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ======================================================================== _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot