Help needed: clearing the 68020 cache.

[Joseph Moran]

In article <83 at brazos.Rice.edu> agesen at daimi.dk (Ole Agesen) writes:
>Can anyone tell me how to clear the cache?
>  Can I get supervisor privileges for a user process?

I hope not. :-)

>  Is there a kernel operation clearing the cache?

In SunOS, you can execute a "trap #2".  This undocumented interface was
used by the old pixrect code that used to build and execute subroutines on
the stack.

On an 020, doing a trap #2 will execute:

	movl #9,d0	# clear and renable instruction cache
	movc d0,cacr
	rte

On an 030, doing a trap #2 will execute:

	movl #3919,d0	# clear and renable instruction and data caches
	movc d0,cacr
	rte

This is exactly what you need.

Joseph Moran
Legato Systems, Inc.
260 Sheridan Avenue
Palo Alto, CA  94306
(415) 329-7886
mojo at Legato.COM or {sun,uunet}!legato!mojo