Re: (03b3542ac93c) hw/ppc/mac_newworld: Restrict RAM to 2 GiB

[BALATON Zoltan]

Hello,

I've seen this commit 03b3542ac93c and remembered that mac99 has a strange 
behaviour that depending on options and if it's in qemu-system-ppc or 
qemu-system-ppc64 it behaves differently and emulates either

- a non-existing Mac config somewhat like a PowerBook (-ppc -M mac99)
- mostly a PowerMac3,1 (-ppc -M mac99,via=pmu)
- or some G5 Mac which is very unfinished yet (-ppc64 -M mac99)

For the first two 32bit configs limiting memory for 2GB is probably the 
right thing to do but a G5 Mac I think could have more RAM but not sure 
where it puts it on real hardware. This is probably not a big problem as 
G5 Mac emulation is not very good but I could at least run Linux on it so 
it somewhat works. Not sure if anybody wants to use it with more than 2GB 
RAM but this change now does not allow that (maybe it did not work 
anyway). I don't know if any action is needed just brought this potential 
problem to your attention. Do what you like with it.

I was also thinking it might be a good idea to break up the mac99 machine 
into multiple machines to avoid the confusing behaviour above and make it 
work more like other machines. This might also be good because 
qemu-system-ppc64 also includes all 32 bit machines as well so that way we 
could get rid of qemu-system-ppc or qemu-system-ppc64 and have only one 
command for all machines and users wouldn't have to know what options to 
use with mac99 to get a G4 or G5 Mac (I think qemu-system-ppc64 -M 
mac99,via=pmu -cpu G4 still works but it's not very intuitive -M 
powermac3_1 would be much clearer). I might give that a try but only if 
Mark would accept such patches otherwise it's just wasted effort to make 
changes to mac_newworld.c.

One thing I'm not sure about is at least that target_ulong is different on 
qemu-system-ppc and qemu-system-ppc64 and if that could cause a problem 
with 32 bit machines. But they are available in ppc64 now and appear to 
works but I was always using qemu-system-ppc so I haven't tested the ppc64 
versions of these machines so there could be some corner cases I don't 
know about.

Regards,
BALATON Zoltan