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Re: [Qemu-ppc] [PATCH] mac99: Bring memory layout closer to real hardwar


From: Programmingkid
Subject: Re: [Qemu-ppc] [PATCH] mac99: Bring memory layout closer to real hardware
Date: Fri, 11 Apr 2014 19:39:39 -0400


On Apr 11, 2014, at 8:28 AM, address@hidden wrote:

On 20.03.14 11:16, BALATON Zoltan wrote:
On Sat, 15 Mar 2014, BALATON Zoltan wrote:
Try to better match the memory map of a PowerMac3,1 model by moving
the pci-cfg mappings to where they are on a real machine. Also add the
VGA card after the macio to let the latter be mapped from 0x80000000 to
match hardware. (On real hardware the graphics card is on a different
bus but we don't seem to model that yet.)

Signed-off-by: BALATON Zoltan <address@hidden>
---

This patch is intended to bring memory layout closer to what's seen in
these dumps:

http://nandra.segv.jp/NetBSD/G4.dump-device-tree.txt
http://raveland.org/ports/eeprom.txt
http://mail-index.netbsd.org/port-macppc/2007/10/24/0000.html
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=604134

It makes MorphOS a little happier and not print alerts when creating
its memory map but not happy enough to not crash later.

I'm not so sure about this patch either by now. I've come across some 
logs that show that these MorphOS alerts can happen on real hardware 
too and are probably not related to the crash but it needs more 
debugging and experimenting. If anyone has any ideas how to converge 
QEMU's model to what's seen in the dumps above please let me know.

Yeah, I'd rather hold back on this until we fix a real bug.

The problem with the mac99 target in QEMU is that it doesn't match any 
real machine out there. It's essentially a hack good enough to get a 
good amount of Linux and Mac OS X working, but I'm sure if you don't 
look at the device tree for device creation you'll blow up :).

The "real" fix would be to create a new machine model that models 
*exactly* a real system from scratch.

So what happens to the mac99 target? Delete or abandon it? Emulating another real Macintosh does sound like a good idea, but that would take a lot of work. Wouldn't it be easier to just adjust the mac99 target instead of starting from scratch? 

If you are intent on making a new target, we should start with a name. It looks like we are targeting the PowerMac3,1. Since it was based on the Sawtooth architecture, I'm thinking sawtooth would be the name to call it. 


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