Re: NetBSD/virt68k live-image

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

mlelstv@wrote:

> tsutsui%ceres.dti.ne.jp@localhost (Izumi Tsutsui) writes:
> 
> >> >[  79.7500030] panic: enter: out of address space
> >> 
> >> 
> >> Yes, I noticed when Jason created virt68k. Amiga also uses pmap_motorola,
> >> there must be another difference.
> 
> >Really? How does amiga handle it?
> 
> I think it's as limited (i.e. 480MB userspace), but there is
> no panic....

It turns out amiga uses own USRSTACK (== VM_MAXUSER_ADDRESS) value
in src/sys/arch/amiga/include/vmparam.h:

---
/*
 * USRSTACK is the top (end) of the user stack.
 */

#ifndef USRSTACK
#define	USRSTACK	0x1E000000
#endif
---

0x1E000000 is 480MB, and mhitch@ noted in the log that
it was intentional value for our 040 pmap design restrictions:

https://github.com/NetBSD/src/commit/61ae8543

>> Raise address of user stack to the highest safe (for 68040 mmu) address,
>> which increases available user address space by 256MB.  One file in
>> pkgsrc/lang/php53 was too large for the amiga.

Actually the panic "enter: out of address space" is triggered by
lack of L2 page, i.e. it could happen by sparse address mappings
without full 480MB allocation.

So it might help other hp300 derived pmap m68k ports to change
VM_MAXUSER_ADDRESS (and VM_MAX_ADDRESS) in vmparam.h to 0x1E000000
from current common 0xFFF00000.

---
Izumi Tsutsui