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. 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. josh _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
