Re: Time to fix the memory allocation on port-amiga

[RadosÅaw Kujawa <radoslaw.kujawa%c0ff33.net@localhost>]

On Dec 21, 2010, at 5:08 AM, John Klos wrote:

> I have to start learning the internals myself if I'm to be useful. Could 
> anyone help me get started, either by suggesting some reading materials or by 
> suggesting a starting place to figure out where to fix these allocation 
> issues? This should be a relatively slow week, and I'd love to get this fixed.

I consider myself a beginner, so I know getting started with kernel development 
is hard. Even if everyday I learn something new about NetBSD internals, there's 
always much to learn. I come across many problems I don't comprehend. Often I 
think I understand how some subsystem works, only to be defeated later by an 
unexplained crash. Surprisingly, NetBSD is quite big and complex OS. While 
extreme portability is cool, sometimes it may pose additional difficulties for 
a person trying to understand how NetBSD works (many abstraction layers, APIs 
trying to be very generic, jumping between machine-independent, 
architecture-dependent and machine dependent source files). We're dealing here 
with obsolete (some people prefer "vintage") architecture and quite modern 
operating system. Even this fact makes some implications: you won't find many 
publications on NetBSD internals, and (perhaps) none about NetBSD kernel on 
Amiga ;).

I'd take a quick look at maxmem variable (defined in 
arch/amiga/amiga/amiga_init.c). Comment suggests that maxmem holds maximum 
possible process size. On most architectures this variable equals physical 
memory size (so you can't have a process larger than you total RAM size). But 
on amiga this is computed in a less obvious way, which I don't even dare to 
understand until I'll get some sleep ;). I'm not sure if this is really related 
to your problem. As far as I remember, Frank once mentioned, that we're not 
using address space beyond 0x1000 0000. This fact may be related. Or not.

If I ever get the time to install NetBSD on my A3000 (total 260MB of Fast RAM), 
then I'll gladly help debugging this problem. However, lack of time is my main 
problem these days...

--
Best regards,
RadosÅaw Kujawa