@node __dpmi_serialize_on_shared_memory, dpmi
@subheading Syntax

@smallexample
#include <dpmi.h>

int __dpmi_serialize_on_shared_memory(unsigned long handle, int flags);
@end smallexample

@subheading Description

Please refer to @ref{DPMI Specification} for details on DPMI
function call operation.  Also see @ref{DPMI Overview} for general
information.

DPMI function AX = 0x0d02 (DPMI 1.0 only).  Not supported by CWSDPMI and
Windows.

This function serializes access to a shared memory block whose handle is
given in @var{handle}.  The bit-mapped variable @var{flags} defines the
following bits:

@table @asis
@item bit 0
If set, return immediately if serialization is unavailable.  If cleared,
the program is suspended until the serialization becomes available.

@item bit 1
If set, perform shared serialization.  If cleared, perform exclusive
serialization.

@item bits 2-15
Reserved (should be zero).
@end table

An @dfn{exclusive serialization} blocks @emph{any} serialization
attempts for the same memory block from other virtual machines.  A
@dfn{shared serialization} blocks only @emph{exclusive} serialization
attempts from other virtual machines.

@subheading Return Value

-1 on error, else zero.

@subheading Portability

@portability !ansi, !posix