linear address, not physical address

Reference: /n/atom/patch/applied2013/monmwaitman
Date: Wed Sep 18 18:45:34 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/man/9/monmwait	Thu Jan  1 00:00:00 1970
+++ /sys/man/9/monmwait	Wed Sep 18 18:45:34 2013
@@ -0,0 +1,50 @@
+.TH MONMWAIT 9
+.SH NAME
+monmwait \- wait for memory write
+.SH SYNOPSIS
+.ta \w'\fLvoid 'u
+.B
+void	monmwait(void *adr, uintptr oldval)
+.SH DESCRIPTION
+Wait for the value pointed to by
+.B adr
+to change from
+.B oldval
+in the most power- and bus-cycle efficient way afforded by
+the architecture.
+.PP
+Since no lock is involved,
+.I monmwait
+may not be used where ABA might be a problem.  This function will
+never  miss a (persistent) change, but may return before the value has
+changed, for example if interrupted, or if a “nearby” memory location
+has been written.
+.I Nearby
+is dependent on the architecture and
+implementation.  On current x86 platforms,
+.I nearby
+means in the
+same cacheline.
+.PP
+The minimal correct implementation would be a no-op.
+On x86 machines, the implementation uses
+the
+.SM MONITOR
+and
+.SM MWAIT
+instructions.
+.SH EXAMPLES
+Application processors can use
+.I monmwait
+while waiting for release to keep the fans from spooling up:
+.IP
+.EX
+while(!active.thunderbirdsarego)
+	monmwait(&active.thunderbirdsarego, 0);
+.EE
+.PP
+.SH SOURCE
+.B /sys/src/nix/k10/l64v.s
+.SH SEE ALSO
+.IR atom (2),
+.IR lock (9)