Christophe Leroy <christophe.le...@csgroup.eu> writes: > Le 12/10/2021 à 08:24, Michael Ellerman a écrit : >> Liu Shixin <liushix...@huawei.com> writes: >>> kindly ping. >> >> I was under the impression you were trying to debug why it wasn't >> working with Christophe. > > The investigation was a bit dormant to be honest since Liu confirmed > that neither KFENCE not DEBUG_PAGEALLOC works.
No worries. Sorry it fell to you to do the investigation. > I now looked at the effort to make it work, and it is not trivial. > At the time being, all linear space is mapped with pinned TLBs and > everything is setup for space 0, with space 1 being used temporarily > when doing heavy changes to space 0. > > We can't use standard pages for linear space on space 0 because we need > memory mapped at all time for exceptions (on booke exception run with > MMU on in space 0). > > In order to use standard pages, we'd need to reorganise the kernel to > have it run mostly in space 1 (for data at least) where we would map > almost everything with standard pages, and keep pinned TLB to map linear > space on space 0 for TLB miss exceptions. Then we'd do more or less like > book3s/32 and switch back into space 1 into other exceptions prolog. > > That could be good to do it as we could maybe have more code in common > with non booke 32 bits, but it is not a trivial job. > > So I suggest that for now, we just make KFENCE and DEBUG_PAGEALLOC > unselectable for booke/32 (e500 and 44x). Yep seems reasonable. cheers
