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.\"	@(#)mincore.2	8.1 (Berkeley) 6/9/93
.\" $FreeBSD$
.\"
.Dd January 17, 2003
.Dt MINCORE 2
.Os
.Sh NAME
.Nm mincore
.Nd determine residency of memory pages
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/mman.h
.Ft int
.Fn mincore "const void *addr" "size_t len" "char *vec"
.Sh DESCRIPTION
The
.Fn mincore
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may be out of date by the time the function returns.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
.Fa addr
and
.Fa len
arguments is not valid.
.It Bq Er EFAULT
The
.Fa vec
argument points to an illegal address.
.El
.Sh SEE ALSO
.Xr madvise 2 ,
.Xr mlock 2 ,
.Xr mprotect 2 ,
.Xr msync 2 ,
.Xr munmap 2 ,
.Xr getpagesize 3
.Sh HISTORY
The
.Fn mincore
system call first appeared in
.Bx 4.4 .