2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
175 lines
4.6 KiB
Groff
175 lines
4.6 KiB
Groff
.\" $NetBSD: makecontext.3,v 1.9 2010/04/29 06:07:35 jruoho Exp $
|
|
.\"
|
|
.\" Copyright (c) 2001, 2009 The NetBSD Foundation, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to The NetBSD Foundation
|
|
.\" by Klaus Klein.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
|
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
.\" POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.Dd April 29, 2010
|
|
.Dt MAKECONTEXT 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm makecontext ,
|
|
.Nm swapcontext
|
|
.Nd manipulate user contexts
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In ucontext.h
|
|
.Ft void
|
|
.Fn makecontext "ucontext_t *ucp" "void (*func)()" "int argc" ...
|
|
.Ft int
|
|
.Fn swapcontext "ucontext_t * restrict oucp" "ucontext_t * restrict ucp"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn makecontext
|
|
function modifies the object pointed to by
|
|
.Fa ucp ,
|
|
which has been initialized using
|
|
.Xr getcontext 2 .
|
|
When this context is resumed using
|
|
.Fn swapcontext
|
|
or
|
|
.Xr setcontext 2 ,
|
|
program execution continues as if
|
|
.Fa func
|
|
had been called with the arguments specified after
|
|
.Fa argc
|
|
in the call of
|
|
.Fn makecontext .
|
|
The value of
|
|
.Fa argc
|
|
must be equal to the number of integer arguments following it,
|
|
and must be equal to the number of integer arguments expected by
|
|
.Fa func ;
|
|
otherwise, the behavior is undefined.
|
|
.Pp
|
|
Before being modified using
|
|
.Fn makecontext ,
|
|
a stack must be allocated for the context (in the
|
|
.Fa uc_stack
|
|
member), and a context to resume after
|
|
.Fa func
|
|
has returned must be determined (pointed to by the
|
|
.Fa uc_link
|
|
member);
|
|
otherwise, the behavior is undefined.
|
|
If
|
|
.Fa uc_link
|
|
is a null pointer, then the context is the main context,
|
|
and the process will exit with an exit status of 0 upon return.
|
|
.Pp
|
|
The
|
|
.Fn swapcontext
|
|
function saves the current context in the object pointed to by
|
|
.Fa oucp ,
|
|
sets the current context to that specified in the object pointed to by
|
|
.Fa ucp ,
|
|
and resumes execution.
|
|
When a context saved by
|
|
.Fn swapcontext
|
|
is restored using
|
|
.Xr setcontext 2 ,
|
|
execution will resume as if the corresponding invocation of
|
|
.Fn swapcontext
|
|
had just returned (successfully).
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn makecontext
|
|
function returns no value.
|
|
.Pp
|
|
On success,
|
|
.Fn swapcontext
|
|
returns a value of 0,
|
|
Otherwise, \-1 is returned and
|
|
.Va errno
|
|
is set to indicate the error.
|
|
.Sh ERRORS
|
|
The
|
|
.Fn swapcontext
|
|
function will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EFAULT
|
|
The
|
|
.Fa oucp
|
|
argument or the
|
|
.Fa ucp
|
|
argument points to an invalid address.
|
|
.It Bq Er EINVAL
|
|
The contents of the datum pointed to by
|
|
.Fa ucp
|
|
are invalid.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr _exit 2 ,
|
|
.Xr getcontext 2 ,
|
|
.Xr setcontext 2 ,
|
|
.Xr ucontext 2
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn makecontext
|
|
and
|
|
.Fn swapcontext
|
|
functions conform to
|
|
.St -xsh5
|
|
and
|
|
.St -p1003.1-2001 .
|
|
.Pp
|
|
The
|
|
.St -p1003.1-2004
|
|
revision marked the functions
|
|
.Fn makecontext
|
|
and
|
|
.Fn swapcontext
|
|
as obsolete, citing portability issues and recommending the use of
|
|
.Tn POSIX
|
|
threads instead.
|
|
The
|
|
.St -p1003.1-2008
|
|
revision removed the functions from the specification.
|
|
.Pp
|
|
.Bf -symbolic
|
|
The standard does not clearly define the type of integer arguments
|
|
passed to
|
|
.Fa func
|
|
via
|
|
.Fn makecontext ;
|
|
portable applications should not rely on the implementation detail that
|
|
it may be possible to pass pointer arguments to functions.
|
|
.Ef
|
|
This may be clarified in a future revision of the standard.
|
|
.Sh HISTORY
|
|
The
|
|
.Fn makecontext
|
|
and
|
|
.Fn swapcontext
|
|
functions first appeared in
|
|
.At V.4 .
|
|
.Sh CAVEATS
|
|
Due to limitations in the current pthread implementation,
|
|
.Nm
|
|
should not be used in programs which link against the
|
|
.Xr pthread 3
|
|
library (whether threads are used or not).
|