.\"	$NetBSD: _lwp_getprivate.2,v 1.6 2013/10/05 09:18:56 njoly Exp $
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Jason R. Thorpe of Wasabi Systems, Inc.
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.Dd September 7, 2013
.Dt _LWP_GETPRIVATE 2
.Os
.Sh NAME
.Nm _lwp_getprivate ,
.Nm _lwp_setprivate
.Nd get and set light-weight process private data
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In lwp.h
.Ft void *
.Fn _lwp_getprivate void
.Ft void
.Fn _lwp_setprivate "void *ptr"
.Sh DESCRIPTION
.Fn _lwp_setprivate
stores the pointer to private data
.Fa ptr
in a location private to the LWP.
.Pp
.Fn _lwp_getprivate
returns the pointer to private data for the LWP.
.Pp
Some platforms provide alternative ways quicker than
.Fn _lwp_getprivate
to use the pointer.
.Bl -tag -width amd64
.It alpha
The pointer can be retrieved by call_pal PAL_rdunique.
.It amd64
The base address of
.Dv %fs
register is set to the pointer so that the private data can be
accessed using the selector.
.It i386
The base address of
.Dv %gs
register is set to the pointer so that the private data can be
accessed using the selector.
.It sparc
.Dv %g7
register is set to the pointer.
.El
.Sh ERRORS
The
.Fn _lwp_getprivate
and
.Fn _lwp_setprivate
functions are always successful, and no return value is reserved to indicate
an error.
.Sh SEE ALSO
.Xr _lwp_makecontext 3
.Sh HISTORY
The
.Fn _lwp_getprivate
and
.Fn _lwp_setprivate
system calls first appeared in
.Nx 2.0 .