On Tue 2015-01-27 13:50:22, Nicolas Pitre wrote: > On Tue, 27 Jan 2015, Russell King - ARM Linux wrote: > > > On Tue, Jan 27, 2015 at 10:16:24AM -0500, Nicolas Pitre wrote: > > > On Tue, 27 Jan 2015, Pavel Machek wrote: > > > > (Note, that in 3.19 dts for n900 got too big, so we are actually > > > > triggering old bugs. That means that this is a regression fix, and > > > > should go in ASAP). > > > > > > It is queued here: > > > http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8294/1 > > > > Irrespective of that patch, I commented on another thread (about adding > > the serial number to DT): > > > > | How about something a little more radical. > > | > > | Rather than trying to squeeze various ATAGs into DT, why don't we add a > > | standard ATAG to contain the DT and pass that through into the kernel. > > | This is IMHO how we _should_ have done the ATAG compatibility from the > > | start. > > | > > | That means we could get rid of most of the libfdt in the decompressor, > > | and instead resolve the differences in the kernel. > > > > That would allow us to get rid of all the FDT compatibility code in the > > decompressor, and when we encounter these special ATAGs, we can deal with > > them in the kernel instead of having to mess around with the DT. I'd > > also assume (although I haven't checked) that it would be much easier to > > add additional DT properties in the kernel environment, rather than in > > the rather restrictive decompressor environment. > > Well... > > I was initially against any ATAG-to-DT compatibility at all. IMHO the > "right" solution is to update the bootloader. > > However people complained that updating the bootloader wasn't possible. > I therefore suggested they go with a shim layer I termed the "impedance > matcher" acting like an intermediate boot stage converting their (often > unofficial and out-of-tree) ATAGs into proper DT nodes. Some people did > exactly that and it works wonderfully for them. It also works > wonderfully for kernel maintenance as the platform specific tweaks are > kept out of the kernel tree. > > Still, that wasn't good enough for some cases as the move to DT > regressed some platforms that just used to work before. Concatenating a > DTB to zImage was tolerable but installing an additional shim layer was > too much. Hence the ATAG-to-DT compat code in the decompressor. This > was meant to smooth things around the transition to DT, etc. After all, > those devices with non-replaceable bootloaders where shim layers are not > possible should get out of commission eventually? N900 is still phone that is best-supported by the mainline, AFAICT. Yes, it is rather sad, but it means that no, it is probably not going out of commission anytime soon. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
