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. cheers -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
