> In netbsd-bugs you write:
> 
> >	MAXBSIZE was #defined to be MAXPHYS in 4.4BSD-Lite (and Lite2).
> >	It was changed to be 16k in NetBSD.  (If my memory serves me,
> >	the reason given at the time was to save kernel page table space
> >	on the i386.
> 
> >	This drastically reduces the effectiveness of clustering (esp.
> >	write clustering), because the number of I/Os which can be combined
> >	is reduced.  (Coalsced I/Os must still fit into a buffer with
> >	maximum size of MAXBSIZE.)
> 
> Wait a moment, please.
> 
> Setting MAXBSIZE=MAXPHYS=64k on my i386/sup19950927 panics at boot
> time. 

That's because the i386 port doesn't properly support expanding kva
space, and doesn't statically allocate the space, either.

It's a bug in the i386 port.


chris