Substantial rewrites to make clearer.

diff --git a/man2/mincore.2 b/man2/mincore.2
index bdf9bb3c101314d7b819c89ac59c24c9bc9ffc8e..f98688da9780d313fa4afe2efaf64bbcef2a86eb 100644 (file)
--- a/man2/mincore.2
+++ b/man2/mincore.2
@@ -1,6 +1,7 @@
 .\" Hey Emacs! This file is -*- nroff -*- source.
 .\"
 .\" Copyright (C) 2001 Bert Hubert <ahu@ds9a.nl>
+.\" and Copyright (C) 2007 Michael Kerrisk <mtk-manpages@gmx.net>
 .\"
 .\" Permission is granted to make and distribute verbatim copies of this
 .\" manual provided the copyright notice and this permission notice are
@@ -28,10 +29,11 @@
 .\" Modified, 30 Apr 2004, Michael Kerrisk <mtk-manpages@gmx.net>
 .\" 2005-04-05 mtk, Fixed error descriptions
 .\"    after message from <gordon.jin@intel.com>
+.\" 2007-01-08 mtk, rewrote various parts
 .\"
-.TH MINCORE 2 2004-04-30 "Linux 2.6.5" "Linux Programmer's Manual"
+.TH MINCORE 2 2007-01-08 "Linux 2.6.5" "Linux Programmer's Manual"
 .SH NAME
-mincore \- get information on whether pages are in core
+mincore \- determine whether pages are resident in memory
 .SH SYNOPSIS
 .B #include <unistd.h>
 .br
@@ -39,36 +41,45 @@ mincore \- get information on whether pages are in core
 .sp
 .BI "int mincore(void *" start ", size_t " length ", unsigned char *" vec );
 .SH DESCRIPTION
-The
 .BR mincore ()
-function requests a vector describing which pages of a file are in core and
-can be read without disk access. The kernel will supply data for
+returns a vector that indicates whether pages 
+of the calling process's virtual memory are resident in core (RAM), 
+and so will not cause a disk access (page fault) if referenced.
+The kernel returns residency information about the pages
+starting at the address
+.IR start ,
+and continuing for 
 .I length
-bytes following the 
-.I start
-address. On return, the kernel will have filled
-.I vec
-with bytes, of which the least significant bit indicates if a page is 
-core resident. (The other bits are undefined, reserved for possible
-later use.)
-Of course this is only a snapshot: pages that are not
-locked in core can come and go any moment, and the contents of
-.I vec
-may be stale already when this call returns.
+bytes.
 
-For
-.BR mincore ()
-to return successfully, 
+The
 .I start
-must lie on a page boundary. It is the caller's responsibility to
-round up to the nearest page. The
+argument must be a multiple of the system page size.
+The
 .I length
-parameter need not be a multiple of the page size. The vector
-.I vec
-must be large enough to contain (length+PAGE_SIZE-1) / PAGE_SIZE bytes.
-One may obtain the page size from
-.BR getpagesize (2).
+argument need not be a multiple of the page size, 
+but since residency information is returned for whole pages,
+.I length
+is effectively rounded up to the next multiple of the page size.
+One may obtain the page size (PAGE_SIZE) using
+.IR sysconf(_SC_PAGESIZE) .
 
+The
+.I vec
+argument must point to an array containing at least
+(length+PAGE_SIZE-1) / PAGE_SIZE bytes.
+On return, 
+the least significant bit of each byte will be set if 
+the corresponding page is currently resident in memory, 
+and be clear otherwise.
+(The settings of the other bits in each byte are undefined;
+these bits are reserved for possible later use.)
+Of course the information returned in
+.I vec
+is only a snapshot: pages that are not
+locked in memory can come and go at any moment, and the contents of
+.I vec
+may already be stale by the time this call returns.
 .SH "RETURN VALUE"
 On success,
 .BR mincore ()
@@ -78,11 +89,11 @@ On error, \-1 is returned, and
 is set appropriately.
 .SH ERRORS
 .B EAGAIN
-kernel is temporarily out of resources
+kernel is temporarily out of resources.
 .TP
 .B EFAULT
 .I vec
-points to an invalid address
+points to an invalid address.
 .TP
 .B EINVAL
 .I start
@@ -108,10 +119,11 @@ to
 .I length
 contained unmapped memory, or memory not part of a file.
 .SH BUGS
+.\" FIXME: mincore() went through some rewrites in 2.6.20-rc;
+.\"        has this affected any of the bugs?
 Up to now (Linux 2.6.5),
 .BR mincore ()
 does not return correct information for MAP_PRIVATE mappings.
-
 .\" Linux (up to now, 2.6.5),
 .\" .B mincore
 .\" does not return correct information for MAP_PRIVATE mappings:
@@ -131,6 +143,8 @@ does not return correct information for MAP_PRIVATE mappings.
 .BR mincore ()
 is not specified in POSIX.1-2001,
 and it is not available on all Unix implementations. 
+.\" It is on at least NetBSD, FreeBSD, OpenBSD, Solaris 8, 
+.\" AIX 5.1, SunOS 4.1
 .SH HISTORY
 The
 .BR mincore ()
@@ -138,6 +152,5 @@ function first appeared in 4.4BSD.
 .SH AVAILABILITY
 Since Linux 2.3.99pre1 and glibc 2.2.
 .SH "SEE ALSO"
-.BR getpagesize (2),
 .BR mlock (2),
 .BR mmap (2)