Re: [Qemu-devel] Unmaintained QEMU builds

[Alexander Graf]

On 04.09.2010, at 16:41, Andreas Färber wrote:

> Am 17.08.2010 um 21:56 schrieb Anthony Liguori:
> 
>> I think we have a lot of dump-and-run features in QEMU whereas someone 
>> writes the patches to implement something and then disappears.  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. 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.

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. 
The big thing is that it costs time to do that and requires documentation, 
which all except for the U4 lack. I'm also fairly sure I won't get to it 
anytime soon :).


Alex