On Wed, 2015-10-07 at 10:31 -0400, Josh Boyer wrote: > On Wed, Oct 7, 2015 at 5:13 AM, Michael Ellerman <m...@ellerman.id.au> wrote: > > On Wed, 2015-10-07 at 02:19 -0500, Segher Boessenkool wrote: > >> On Wed, Oct 07, 2015 at 05:00:49PM +1100, Michael Ellerman wrote: > >> > > It's also worth noting that the __flush_power7 uses tlbiel instead of > >> > > tlbie. > >> > > >> > Yeah that's a good point. It's not clear if the swsusp code wants to a > >> > local or > >> > a global invalidate. > >> > >> If I read the code right, this is called on the boot CPU when all the > >> non-boot CPUs are still (potentially) down, so if you would do a global > >> invalidate the non-boot CPUs might not even notice, so those need to do > >> a (local) invalidate after being brought up anyway? Or they probably > >> need it before being brought down at all? You figure it out, it makes > >> my brain hurt :-) > > > > A good rule would be that every cpu does a local invalidate before turning > > on > > the MMU. That would work for this case and also for kexec, kdump, junk left > > by > > firmare etc. But I don't think we do that consistently in a way that works > > for > > this code at the moment. > > > >> > As an alternative, can you try adding a .machine push / .machine > >> > "power4" / > >> > .machine pop, around the tlbie. That should tell the assembler to drop > >> > back to > >> > power4 mode for that instruction, which should then do the right thing. > >> > There > >> > are some examples in that file. > >> > >> That will get the assembler to not complain, but it will assemble the wrong > >> instruction: the power7 instruction has the same opcode (but different > >> semantics). So if you assemble a "tlbie r4" in power4 mode, a newer CPU > >> will see it as a "tlbie r4,r0" and do the wrong thing. > > > > Yeah, it would basically maintain the existing behaviour which is wrong but > > a > > known quantity. I suspect no one has ever run this on Power7 or in fact > > anything other than G5 or Book3E. > > Likely not, but leaving it broken just because it is known behavior > seems pretty weird to me.
In a universe where I have infinite time to fix random things we would obviously do a proper fix :) > I think Fedora will look at simply disabling hibernation on ppc64 so the file > isn't built at all. Seems to be a safer option. It's safer for sure. Though you might have some G5 users who are using it and notice it being disabled. cheers _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
