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.\"	@(#)mincore.2	8.1 (Berkeley) 6/9/93
.\"
.Dd June 6, 1999
.Dt MINCORE 2
.Os
.Sh NAME
.Nm mincore
.Nd determine residency of memory pages
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/mman.h>
.Ft int
.Fn mincore "void *addr" "size_t len" "char *vec"
.Sh DESCRIPTION
The
.Fn mincore
system call
allows a process to obtain information about whether pages are
core resident.  The status of the memory range is returned in the
character-per-page array
.Ar vec .
If the page is resident, the least significant bit of the corresponding
character in
.Ar vec
will be set.  Other bits are reserved for additional information
which future implementations may return.
.Pp
Note that the status of each page may change between the call to
.Fn mincore
and the return of the page status information.  In order to guarantee
that pages will remain in core, the address range must be locked with
.Xr mlock 2 .
.Sh RETURN VALUES
.Fn mincore
returns 0 on success, or -1 on failure and sets the variable
.Va errno
to indicate the error.
.Sh ERRORS
The    
.Fn mincore
call will fail if:
.Bl -tag -width Er
.It Bq Er EFAULT
.Ar vec
points to an illegal address.
.It Bq Er EINVAL
.Ar addr
is not a multiple of the system page size.
.It Bq Er EINVAL
.Ar len
is equal to 0.
.It Bq Er ENOMEM
The address range specified is invalid for the calling process,
or one or more of the pages specified in the range are not mapped.
.El
.Sh SEE ALSO
.Xr madvise 2 ,
.Xr mlock 2 ,
.Xr mprotect 2 ,
.Xr msync 2 ,
.Xr munmap 2 ,
.Xr sysconf 3
.Sh HISTORY
The
.Fn mincore
function first appeared in
.Bx 4.4 .