On Wed, Mar 20, 2024 at 05:40:39PM +0000, Christophe Leroy wrote: > > > Le 20/03/2024 à 17:09, Peter Xu a écrit : > > On Wed, Mar 20, 2024 at 06:16:43AM +0000, Christophe Leroy wrote: > >> At the first place that was to get a close fit between hardware > >> pagetable topology and linux pagetable topology. But obviously we > >> already stepped back for 512k pages, so let's go one more step aside and > >> do similar with 8M pages. > >> > >> I'll give it a try and see how it goes. > > > > So you're talking about 8M only for 8xx, am I right? > > Yes I am. > > > > > There seem to be other PowerPC systems use hugepd. Is it possible that we > > convert all hugepd into cont_pte form? > > Indeed. > > Seems like we have hugepd for book3s/64 and for nohash. > > For book3s I don't know, may Aneesh can answer. > > For nohash I think it should be possible because TLB misses are handled > by software. Even the e6500 which has a hardware tablewalk falls back on > software walk when it is a hugepage IIUC. It'll be great if I can get some answer here, and then I know the path for hugepd in general. I don't want to add any new code into core mm to something destined to fade away soon. One option for me is I can check a macro of hugepd existance, so all new code will only work when hugepd is not supported on such arch. However that'll start to make some PowerPC systems special (which I still tried hard to avoid, if that wasn't proved in the past..), meanwhile we'll also need to keep some generic-mm paths (that I can already remove along with the new code) only for these hugepd systems. But it's still okay to me, it'll be just a matter of when to drop those codes, sooner or later. Thanks, -- Peter Xu
