Cédric Le Goater <c...@kaod.org> writes: > On 11/26/21 13:13, Fabiano Rosas wrote: >> Segher Boessenkool <seg...@kernel.crashing.org> writes: >> >>> Hi! >>> >>> On Fri, Nov 26, 2021 at 09:34:44AM +0100, Cédric Le Goater wrote: >>>> On 11/25/21 10:38, Segher Boessenkool wrote: >>>>> On Thu, Nov 25, 2021 at 01:45:00AM +0100, BALATON Zoltan wrote: >>>>>> As for guests, those running on the said PowerMac G4 should have support >>>>>> for these CPUs so maybe you can try some Mac OS X versions (or maybe >>>>> >>>>> OSX uses hardware pagetables. >>>>> >>>>>> MorphOS but that is not the best for debugging as there's no source >>>>>> available nor any help from its owners but just to see if it boots it may >>>>>> be sufficient, it should work on real PowerMac G4). >>>>> >>>>> I have no idea what MorphOS uses, but I bet HPT as well. That is >>>>> because HPT is fastest in general. Software TLB reloads are good in >>>>> special cases only; the most common is real-time OSes, which can use its >>>>> lower guaranteed latency for some special address spaces (and can have a >>>>> simpler address map in general). >>>> >>>> The support was added to QEMU knowing that Linux didn't handle soft TLBs. >>>> And the commit says that it was kept disabled initially. I guess that was >>>> broken these last years. >>> >>> Ah :-) So when was it enabled, do you know? >> >> Hm.. That commit message does not match the code. They simply added the >> software TLB implementation to an already existing SOFT_74xx MMU >> model. I don't see anything that would keep it disabled at that time. >> > > because most of the cpu definitions in ppc_defs[] are protected by a : > > #if defined (TODO) > > See below. commit 8ca3f6c3824c ("Allow selection of all defined PowerPC > 74xx (aka G4) CPUs.") removed the TODO without a reason :/ This is old, > when SVN was in used.
Ah nice catch!