danc%sri-tsca@turtlevax.UUCP (03/13/85)
In machine/pte.h there are two fields in the VAX "struct pte" that
don't seem to be used for anything. They are "pg_vreadm" and "pg_swapm".
From looking at vm_mem.c and vm_page.c, it seems that pg_vreadm was
a remnant from something Berkeley never got around to doing. It
relates to "pg_fod" (Fill-on-demand) and "pg_fileno" in "struct fpte".
My guess is pg_vreadm has something to do with being able to
pagein text/data from files other than the file that was exec-ed
(maybe part of a shared-memory scheme or something)???
I have no idea what pg_swapm was intended for. Anyone know for
sure what the origin and/or use of these fields are? We are porting
the virtual-memory code to a 68020, and I don't want to eliminate them
if 4.3BSD (or whatever they plan to call it) makes use of them. Thanks!
-Dan Chernikoff
Cadlinc, Inc
Arpanet: dan@sri-tsc
Usenet: {decwrl,hplabs}!turtlevax!danc