Re: [Qemu-devel] [Qemu-ppc] [PATCH] adb: change handler only when recognized

[BALATON Zoltan]

On Tue, 9 Aug 2016, Benjamin Herrenschmidt wrote:
> On Tue, 2016-08-09 at 02:11 +0200, BALATON Zoltan wrote:
> > I don't know much about this but I've read here 
> > > <http://mcosre.sourceforge.net/docs/apple_io.html> that there are three 
> > different kind of chips: CUDA, PMU99 and PMU. Confusingly both PMU-s are 
> > > called via-pmu by Apple.
>
> And there's Egret ... ;-)

Right, for completeness, but that's only in very old machines we don't 
emulate in QEMU.

> >  However, desktop machines have no ADB so I'm not sure why we have 
> > > one still in QEMU.
>
> Because PowerBooks do (or rather a PMU-simulation of ADB) and MacOS
> doesn't care. If ADB is in the device-tree, it will use it. It makes
> things easier to support multiple combinations especially when
> "comparing" things for debug.
>
> Additionally, USB doesn't work well in OpenBIOS at this point ;-)

In what way? Keyboard works. What else is needed?

> Also, I have some evil plan to change the way ADB autopoll works in
> Qemu so that the devices signal the PMU when they want to talk. That
> will avoid having yet another 30-something HZ timer ticking in qemu,
> and in that regard will probably be more efficient (read: slows down
> the emulator less) than OHCI.

OK, this is a really nice thing and justifies having an ADB bus. (This 
would also likely fix mouse problems seen by others.)

> >  If USB is working then we don't need ADB with PMU99 and 
> > > that could resolve all the problems with it.
>
> I have solved the ADB problems so there's nothing left to solve here :-
> ) But see above why I think it's a good idea to keep ADB as an option.
>
> >  We can keep it to old world 
> > beige G3 with CUDA where it works. I think only some Powerbooks have PMU 
> > > and ADB but we are not targeting that.
>
> Why not ?

Just thought emulating all the additional details for Powerbook power 
management might be difficult. But if you're willing to go there I won't 
stop you. :-) Obviously you understand this very well so maybe it's not 
that difficult for you.

> >  Here's an (untested) patch for
> > switching to using USB keyboard and mouse instead of ADB unless USB is 
> > disabled. (The device tree should be changed accordingly in OpenBIOS.) Not 
> > sure if this is helpful.
>
> Don't bother just yet, as I said, I am reworking all of that code. I will
> probably just create various -machine options so you can chose what bits
> and pieces you want to put togeher, ie, CUDA, PMU, with or without ADB,
> which machine model string to expose to the OS etc...

Cool, looking forward to it. Thanks for all the great stuff you did for 
this and keep it up.

Regards,
BALATON Zoltan