112 lines
3.7 KiB
Groff
112 lines
3.7 KiB
Groff
.\" $NetBSD: _lwp_create.2,v 1.11 2022/12/04 16:17:50 uwe Exp $
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.\"
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.\" Copyright (c) 2003 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Jason R. Thorpe of Wasabi Systems, Inc.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd April 21, 2017
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.Dt _LWP_CREATE 2
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.Os
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.Sh NAME
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.Nm _lwp_create
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.Nd create a new light-weight process
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In lwp.h
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.Ft int
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.Fn _lwp_create "ucontext_t *context" "unsigned long flags" "lwpid_t *new_lwp"
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.Sh DESCRIPTION
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.Fn _lwp_create
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causes creation of a new light-weight process, or LWP, and adds it to the
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current process.
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The
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.Fa context
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argument specifies the initial execution context for the new LWP including
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signal mask, stack, and machine registers.
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The signal stack of the newly created light-weight process is reset to
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disabled.
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If this context specifies invalid register values (for example privilege
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escalation by setting machine dependent bits forbidden for user processes),
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or does not specify cpu register values
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.Fa ( uc_flags
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does not have the
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.Dv _UC_CPU
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bit set), the call will fail and errno will be set to
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.Er EINVAL .
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.Pp
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The following flags affect the creation of the new LWP:
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.Bl -tag -width Dv
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.It Dv LWP_DETACHED
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The LWP is created detached.
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The resources associated with a detached LWP will be automatically
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reclaimed by the system when the LWP exits.
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Otherwise, a terminated LWP's resources will not be reclaimed until
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its status is reported to another LWP via
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.Xr _lwp_wait 2 .
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.It Dv LWP_SUSPENDED
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The LWP is created suspended, and will not begin execution until
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it is resumed by another LWP via
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.Xr _lwp_continue 2 .
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.\" __LWP_ASLWP is not yet implemented by the NetBSD kernel.
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.El
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.Pp
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The LWP ID of the new LWP is stored in the location pointed to by
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.Fa new_lwp .
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.Sh RETURN VALUES
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.Rv -std _lwp_create
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.Sh ERRORS
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.Fn _lwp_create
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will fail and no LWP will be created if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The system-imposed limit on the total
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number of LWPs under execution would be exceeded.
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This limit is configuration-dependent.
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.It Bq Er EFAULT
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The address pointed to by
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.Fa context
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or
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.Fa new_lwp
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is outside the process's allocated address space.
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.It Bq Er EINVAL
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The
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.Vt ucontext_t
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passed is invalid.
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.It Bq Er ENOMEM
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There is insufficient swap space for the new LWP.
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.El
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.Sh SEE ALSO
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.Xr _lwp_continue 2 ,
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.Xr _lwp_exit 2 ,
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.Xr _lwp_wait 2 ,
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.Xr _lwp_makecontext 3
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.Sh HISTORY
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The
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.Fn _lwp_create
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system call first appeared in
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.Nx 2.0 .
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