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Do a better job of documenting mincore(2), esp. the MINCORE_* flags.

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This commit is contained in:
Tim J. Robbins 2003-01-17 04:06:57 +00:00
parent 7643dc189d
commit 0cff97c8bc
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=109404
1 changed files with 46 additions and 14 deletions
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60
lib/libc/sys/mincore.2
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@ -32,12 +32,12 @@
.\" @(#)mincore.2 8.1 (Berkeley) 6/9/93
.\" $FreeBSD$
.\"
.Dd June 9, 1993
.Dd January 17, 2003
.Dt MINCORE 2
.Os
.Sh NAME
.Nm mincore
.Nd get advice about use of memory
.Nd determine residency of memory pages
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
@ -47,17 +47,50 @@
.Sh DESCRIPTION
The
.Fn mincore
system call
allows a process to obtain information about whether pages are
core resident.
Here the current core residency of the pages is returned
in the character array
.Fa vec ,
with a value of 1 meaning
that the page is in-core.
system call determines whether each of the pages in the region beginning at
.Fa addr
and continuing for
.Fa len
bytes is resident.
.\"The beginning address,
.\".Fa addr ,
.\"is first rounded down to a multiple of the page size (see
.\".Xr getpagesize 3 Ns ).
.\"The end address,
.\".Fa addr No + Fa len ,
.\"is rounded up to a multiple of the page size.
The status is returned in the
.Fa vec
array, one character per page.
Each character is either 0 if the page is not resident, or a combination of
the following flags (defined in
.Sy <sys/mman.h> Ns No ) Ns :
.Bl -tag -width ".Dv MINCORE_REFERENCED_OTHER"
.It Dv MINCORE_INCORE
Page is in core (resident).
.It Dv MINCORE_REFERENCED
Page has been referenced by us.
.It Dv MINCORE_MODIFIED
Page has been modified by us.
.It Dv MINCORE_REFERENCED_OTHER
Page has been referenced.
.It Dv MINCORE_MODIFIED_OTHER
Page has been modified.
.El
.Pp
The information returned by
.Fn mincore
may be out of date by the time the function returns.
The only way to ensure that a page is resident is to lock it into memory
with the
.Xr mlock 2
function.
.Sh RETURN VALUES
.Rv -std mincore
.Sh ERRORS
The
.Fn mincore
function will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The virtual address range specified by the
@ -70,14 +103,13 @@ The
.Fa vec
argument points to an illegal address.
.El
.Sh BUGS
This man page is incorrect.
The vector description is wrong.
.Sh SEE ALSO
.Xr madvise 2 ,
.Xr mlock 2 ,
.Xr mprotect 2 ,
.Xr msync 2 ,
.Xr munmap 2
.Xr munmap 2 ,
.Xr getpagesize 3
.Sh HISTORY
The
.Fn mincore