On Thu, Aug 1, 2013 at 10:37 AM, Jonas Bonn <jo...@southpole.se> wrote: > On 07/31/2013 03:11 PM, Stefan Kristiansson wrote: >> I'm not going to put up a big fight about keeping the xMMUPR >> registers, but they _are_ in the arch spec as of now and even though >> X/W/U are well defined and sufficient for the Linux case, >> is that true for all other cases? > > > I say "yes, it's sufficient". I hereby put the challenge to the list to > come up with a _reasonable_ combination that's not possible with the above 3 > bits, along with an explanation of the use case that requires it. >
A reasonable combination would be superuser read & write, but user read only. As for use cases... /me shrugs... 3-bits seems to be enough for x86, so why wouldn't it for us? >> >> It's of course still possible to do the lookup table approach without >> the actual registers by using a static map to X/W/U, >> both in software and hardware. > > > That must be a simpler HW implementation... right? For SW it's definitely > better. > Probably slightly simpler (in terms of written code and generated logic), yes. But we digress into this not so important discussion about keeping or not keeping the xMMUPRs, when there are more interesting things to decide on. I personally will not miss them much, so let's say we wipe them, unless someone else have an objection to it when all the more gory things have been handled. Stefan _______________________________________________ Linux mailing list Linux@lists.openrisc.net http://lists.openrisc.net/listinfo/linux
