Re: [Qemu-devel] Unmaintained ppc features (was: Unmaintained QEMU builds)

[Andreas Färber]

Am 05.09.2010 um 12:03 schrieb Alexander Graf:

> On 04.09.2010, at 16:41, Andreas Färber wrote:
>
> > Am 17.08.2010 um 21:56 schrieb Anthony Liguori:
> >
> > > Often time, the feature is not generally useful so the code just  
> > > rots.  I think an awful lot of the PPC boards and devices also  
> > > fall into this category.
> > >
> > > Considering that we're well over half a million lines of code  
> > > today, I think we would do ourselves a favor by dropping some of  
> > > the dead features we're carrying.
> >
> > The only really broken ppc sysemu should be PReP atm, no? Otherwise  
> > I'm just aware of some OpenBIOS bugs.
>
> Qemu currently tries to potentially emulate every CPU flavor that  
> ever existed in the world.

Yeah, noticed the diversity and the hardly comprehensible macros  
during the TCG conversion.

Yet conditionalizing instructions based on CPU doesn't seem wrong when  
you notice it in the manuals, arm does it too and Paul insisted on  
contributors doing that right.

> I have no idea if the original 601 implementation still works. Or  
> 603. Not to speak of the halfway-implemented BookE CPUs. I'm also  
> fairly sure that no emulated 64 bit CPU but the G5 work.
>
> I think the right thing to do for PPC would be to focus on a subset  
> of CPUs we care about and make sure those work in combination.
>
> Also, the board emulation is ... eh ... suboptimal. The code is  
> weirdly structured and I've already squashed a lot of bugs in there  
> to make it barely work with Linux, but I have no idea about other OSs.

Haiku/ppc was not working yet, I'm tracking some ofmem issues in  
OpenBIOS.
http://permalink.gmane.org/gmane.comp.bios.openbios/3090

> The thing we _really_ should do there would be a from-scratch  
> implementation of a U2 (32-bit) and a U3/U4 (64-bit) board and just  
> forget about the old stuff.

While the PowerMacs are my main focus, I would actually be curious  
about 'old' BeBox emulation (dual 603, proprietary boot ROM; a GSoC  
suggestion) and interested in some new AIX capable machine (possibly  
reusing the now untested POWER stuff?).

And it seemed like Hollis were still using some ppcemb board at his  
new job.

Andreas