On Wed, Apr 5, 2017 at 7:38 PM, Nicholas Piggin <npiggin@xxxxxxxxx> wrote: > On Thu, 06 Apr 2017 06:58:01 +1000 > Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> wrote: > >> On Wed, 2017-04-05 at 10:58 -0500, Rob Herring wrote: >> > Well, I'd like to avoid expanding usage of flat DT parsing in the >> > kernel. But you could just put this function into arch/powerpc and I'd >> > never see it, but I like that even less. Mainly, I just wanted to >> > raise the point. >> > >> > Your argument works until you need that setup in assembly code, then >> > you are in the situation that you need to either handle the setup in >> > bootloader/firmware or have an simple way to determine that condition. >> >> The main issue is that changing that is a very very invasive change in >> an extremely fragile and rather nasty area of code shared by 32 and 64- >> bit for which we don't even have easy access to all the machines to >> test with anymore :) >> >> It's probably not impossible, but it would delay the new cpu feature >> stuff that Nick is making by a lot, probably monthes, making it nearly >> impossible to get back into distros etc... >> >> So while it might be something to consider, I would definitely keep >> that as a separate unit of work to do later. > > Yeah, it's no longer a "drop in" replacement for existing features > testing if we do this, which makes it hard to backport too (we will > need this for compatibility with future firmware, so it will have to > go into distro kernels.) > > Given that it's quite a small addition to of/fdt code, hopefully > that gives you a reasonable justification to accept it. > > If you prefer not to, that's okay, but I think we would have to carry > it in arch/powerpc at least for a time, because of the schedule we're > working to for POWER9 enablement. As a longer term item I agree with you > and Ben, it would be worth considering unflattening earlier. As I mentioned, keeping it in arch/powerpc I like even less. So this is fine. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
