Re: [PATCH 0/4] Atari kernel-in-FastRAM patches, take three

[Scott Holder <scott@iamscott.net>]

On 4/1/2014 8:23 AM, Finn Thain wrote:
> On Tue, 1 Apr 2014, Geert Uytterhoeven wrote:
>
>> <snip>
>>
>> Don't know about Mac,
> It may be possible to boot Linux with MacOS running in 24-bit mode, and
> ISTR that this leads to a large number of memory chunks. The Penguin
> documentation says use 32-bit mode (which means installing Mode32 if you
> have old MacOS and old ROMs). The only Mac I have here is running MacOS
> 7.6 so I can't test 24-bit mode. You can see the debug output from Penguin
> below.

I happen to have my crazy PearPC/Mac OS X-booting LC475 still up and 
running with a 7.5.5 system folder on it. I rebooted it into 24-bit mode 
and loading Penguin does give a warning that 32-bit mode works better. 
Attempting to boot generates:

*** Too many memory ranges!!!
Error:
*** setup_ram_mappings() failure - too many mappings

I have a 64mb simm in this LC475; I tried popping it out (leaving me 
with 4mb) and it actually did attempt to unpack the kernel, but there's 
too little memory to do it. I have a bagful of smaller 72-pin simms 
kicking around somewhere; I'll have to dig it out of the closet and try 
it again.

Sadly my IIci is still misbehaving due to bad caps. I do have a working 
840AV here... I believe it should work in 24-bit mode. I don't have any 
older 32-bit unclean Macs of the era when 24-bit was normal to try with 
to see if maybe the memory controller works better.

>
>> but I have some memories of interleaved banks and such...
> There are some Mac models with memory controllers that do interleaving. I
> don't know whether interleaving is relevant here. I'd have to consult the
> Penguin source code to know whether it behaves differently on different
> models.

All I can say here is I ran 2.0-era kernels on a Quadra 840AV which does 
have interleaved RAM way back in the day just fine. I haven't yet gotten 
modern kernels (even the setup that works on the LC475) booting on it 
yet; sadly I'm not much good for coding or debug tracing.

Scott