CVS commit: src/sys/uvm

["Jason R Thorpe" <thorpej%netbsd.org@localhost>]

Module Name:    src
Committed By:   thorpej
Date:           Sat Apr 18 03:27:13 UTC 2020

Modified Files:
        src/sys/uvm: uvm_extern.h uvm_map.c

Log Message:
Add an API to get a reference on the identity of an individual byte of
virtual memory, a "virtual object address".  This is not a reference to
a physical byte of memory, per se, but a reference to a byte residing
in a page, owned by a unique UVM object (either a uobj or an anon).  Two
separate address+addresses space tuples that reference the same byte in
an object (such as a location in a shared memory segment) will resolve
to equivalent virtual object addresses.  Even if the residency status
of the page changes, the virtual object address remains unchanged.

struct uvm_voaddr -- a structure that encapsulates this address reference.

uvm_voaddr_acquire() -- a function to acquire this address reference,
given a vm_map and a vaddr_t.

uvm_voaddr_release() -- a function to release this address reference.

uvm_voaddr_compare() -- a function to compare two such address references.

uvm_voaddr_acquire() resolves the COW status of the object address before
acquiring.

In collaboration with riastradh@ and chs@.


To generate a diff of this commit:
cvs rdiff -u -r1.222 -r1.223 src/sys/uvm/uvm_extern.h
cvs rdiff -u -r1.378 -r1.379 src/sys/uvm/uvm_map.c

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