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MINCORE(2)		  FreeBSD System Calls Manual		    MINCORE(2)

NAME
     mincore --	determine residency of memory pages

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <sys/mman.h>

     int
     mincore(const void	*addr, size_t len, char	*vec);

DESCRIPTION
     The mincore() system call determines whether each of the pages in the re-
     gion beginning at addr and	continuing for len bytes is resident or
     mapped, depending on the value of sysctl vm.mincore_mapped.  The status
     is	returned in the	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 <sys/mman.h>):

     MINCORE_INCORE	       Page is in core (resident).

     MINCORE_REFERENCED	       Page has	been referenced	by us.

     MINCORE_MODIFIED	       Page has	been modified by us.

     MINCORE_REFERENCED_OTHER  Page has	been referenced.

     MINCORE_MODIFIED_OTHER    Page has	been modified.

     MINCORE_PSIND(i)	       Page is part of a large ("super") page with
			       size given by index i in	the array returned by
			       getpagesizes(3).

     MINCORE_SUPER	       A mask of the valid MINCORE_PSIND() values.  If
			       any bits	in this	mask are set, the page is part
			       of a large ("super") page.

     The information returned by mincore() may be out of date by the time the
     system call returns.  The only way	to ensure that a page is resident is
     to	lock it	into memory with the mlock(2) system call.

     If	the vm.mincore_mapped sysctl is	set to a non-zero value	(default),
     only the current process' mappings	of the pages in	the specified virtual
     address range are examined.  This does not	preclude the system from re-
     turning MINCORE_REFERENCED_OTHER and MINCORE_MODIFIED_OTHER statuses.
     Otherwise,	if the sysctl value is zero, all resident pages	backing	the
     specified address range are examined, regardless of the mapping state.

IMPLEMENTATION NOTES
     Prior to the introduction of MINCORE_PSIND() in FreeBSD 13.0,
     MINCORE_SUPER consisted of	a single bit equal to MINCORE_PSIND(1).	 In
     particular, applications compiled using the old value of MINCORE_SUPER
     will not identify large pages with	size index 2 as	being large pages.

RETURN VALUES
     The mincore() function returns the	value 0	if successful; otherwise the
     value -1 is returned and the global variable errno	is set to indicate the
     error.

ERRORS
     The mincore() system call will fail if:

     [ENOMEM]		The virtual address range specified by the addr	and
			len arguments is not fully mapped.

     [EFAULT]		The vec	argument points	to an illegal address.

SEE ALSO
     madvise(2), mlock(2), mprotect(2),	msync(2), munmap(2), getpagesize(3),
     getpagesizes(3)

HISTORY
     The mincore() system call first appeared in 4.4BSD.

FreeBSD	13.0			August 23, 2020			  FreeBSD 13.0

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | IMPLEMENTATION NOTES | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

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