Bug in 4.2bsd with >8Meg of physical memory

[dwight at jove.UUCP]

Here's the problem:
	We have an 11/780 with 14Meg of memory. However when we
	gen the kernel with the necessary changes to locore.s and
	cmap.h to allow us to use it all, the system gets very
	flakey (large (6Meg) thrashers have their address spaces
	corrupted, things randomly dump core and so on). The
	system finds all 14M and allocates buffer space
	accordingly and everything goes fine until any
	heavy virtual memory activity starts up. I'm sure it's
	not a minor problem with kernel loading or compilation
	(I removed all the .o's before recompiling etc.).
	The changes I made were those mentioned in the back of the
	config manual, index fields in cmap.h (c_next & c_prev)
	expanded to 14 bits and a constant in locore.s changed
	to 16384. We know the memory is ok. We are running
	ok on 8Meg now.

	Has anybody experienced this problem?

ps.  I found some hardwired constants in Fastreclaim()
	dealing with the cmap and tried fixing them but
	I managed to make things worse.

Dwight Melcher
{ucbvax!hplabs,allegra!nbires,decvax!kpno,harpo!seismo,ihnp4!kpno}!hao!boulder!dwight