README: this is the change I warned you about

[Jason Thorpe <thorpej%nas.nasa.gov@localhost>]

This is that UVM change that I warned you about yesterday.

------- Forwarded Message

Module Name:    syssrc
Committed By:   thorpej
Date:           Wed Jun 16 19:34:25 UTC 1999

Modified Files:
        syssrc/sys/uvm: uvm_map.c

Log Message:
Modify uvm_map_pageable() and uvm_map_pageable_all() to follow POSIX 1003.1b
semantics.  That is, regardless of the number of mlock/mlockall calls,
an munlock/munlockall actually unlocks the region (i.e. sets wiring count
to 0).

Add a comment describing why uvm_map_pageable() should not be used for
transient page wirings (e.g. for physio) -- note, it's currently only
(ab)used in this way by a few pieces of code which are known to be
broken, i.e. the Amiga and Atari pmaps, and i386 and pc532 if PMAP_NEW is
not used.  The i386 GDT code uses uvm_map_pageable(), but in a safe
way, and could be trivially converted to use uvm_fault_wire() instead.


To generate a diff of this commit:
cvs rdiff -r1.55 -r1.56 syssrc/sys/uvm/uvm_map.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.


------- End of Forwarded Message

        -- Jason R. Thorpe <thorpej%nas.nasa.gov@localhost>