.\"	$OpenBSD: compat_svr4.8,v 1.16 2007/05/31 19:19:58 jmc Exp $
.\"	$NetBSD: compat_svr4.8,v 1.1 1996/07/06 17:14:50 christos Exp $
.\"
.\" Copyright (c) 1996 Christos Zoulas
.\" All rights reserved.
.\"
.\" 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.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgment:
.\"      This product includes software developed for the NetBSD Project
.\"      by Christos Zoulas
.\" 4. The name of the author may not be used to endorse or promote products
.\"    derived from this software without specific prior written permission
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
.\"
.\"	Stolen from compat_linux.8,v 1.2 1995/10/16 20:17:59 fvdl
.\"
.Dd $Mdocdate: May 31 2007 $
.Dt COMPAT_SVR4 8
.Os
.Sh NAME
.Nm compat_svr4
.Nd setup for running SVR4/iBCS2 binaries under emulation
.Sh DESCRIPTION
.Ox
supports running SVR4/iBCS2 binaries.
This code has been tested on i386 and sparc systems.
Most programs should work, but not ones that use or depend on:
.Pp
.Bl -tag -width 123 -compact -offset indent
.It kernel internal data structures
.It the
.Pa /proc
filesystem
.It the ticotsord loopback rpc mechanism (NIS uses this)
.It sound and video interfaces
.It threads (ttsession uses threads)
.It the streams administrative driver
.El
.Pp
The SVR4 compatibility feature is active
for kernels compiled with the
.Nm COMPAT_SVR4
option and kern.emul.svr4
.Xr sysctl 8
enabled.
.Pp
Most SVR4 programs are dynamically linked.
This means that the shared libraries that the programs depend on
and the runtime linker are also needed.
Additionally, a "shadow root" directory for SVR4 binaries
on the
.Ox
system will have to be created.
This directory is named
.Pa /emul/svr4 .
Any file operations done by SVR4 programs run under
.Ox
will look in this directory first.
So, if a SVR4 program opens, for example,
.Pa /etc/passwd ,
.Ox
will
first try to open
.Pa /emul/svr4/etc/passwd ,
and if that does not exist open the `real'
.Pa /etc/passwd file .
It is recommended that SVR4 packages that include configuration
files, etc., be installed under
.Pa /emul/svr4 ,
to avoid naming conflicts with possible
.Ox
counterparts.
Shared libraries should also be installed in the shadow tree.
.Pp
The simplest way to set up the system for SVR4 binaries is:
.Bl -tag -width 123 -compact
.It 1.
Make the necessary directories:
.Bd -literal -offset indent
(me@openbsd) mkdir -p /emul/svr4/{dev,etc}
(me@openbsd) mkdir -p /emul/svr4/usr/{bin,lib}
(me@openbsd) mkdir -p /emul/svr4/usr/openwin/{bin,lib}
.Ed
.Pp
.It 2.
Copy files from an SVR4 system:
.Bd -literal -offset indent
(me@svr4) cd /usr/lib
(me@svr4) tar -cf -\ . | \e
     rsh openbsd 'cd /emul/svr4/usr/lib; tar -xpf -'
.Ed
.Pp
If OpenWindows is going to be run:
.Bd -literal -offset indent
(me@svr4) cd /usr/openwin/lib
(me@svr4) tar -cf -\ . | \e
     rsh openbsd 'cd /emul/svr4/usr/openwin/lib; tar -xpf -'
.Ed
.Pp
.It 3.
Set up the configuration files and devices:
.Bd -literal -offset indent
(me@openbsd) cd /usr/src/etc/etc.svr4
(me@openbsd) cp netconfig nsswitch.conf /emul/svr4/etc
(me@openbsd) cp SVR4_MAKEDEV /emul/svr4/dev
(me@openbsd) cd /emul/svr4/dev; sh SVR4_MAKEDEV all
.Ed
.El
.Pp
An alternative method is to mount a whole SVR4 partition in
.Pa /emul/svr4
and then override with other mounts
.Pa /emul/svr4/etc
and
.Pa /emul/svr4/dev .
.Pp
Clearly, a complete SVR4
.Pa /dev
directory cannot be used as
.Pa /emul/svr4/dev ,
because other device nodes, such as
.Pa /dev/null ,
need to be
.Ox
device nodes.
.Sh BUGS
Many system calls are still not emulated.
The streams emulation is incomplete (socketpair does not work yet).
.Pp
Most SVR4 executables can not handle directory offset cookies > 32
bits.
More recent ones, compiled for large file support (Solaris 2.6 and up) can.
With older programs, the message
"svr4_getdents: dir offset too large for emulated program"
will appear when this happens.
Currently, this can only happen on NFS mounted filesystems, mounted from
servers that return offsets with information in the upper 32 bits.
These errors should rarely happen, but can be avoided by mounting this
filesystem with the
.Fl 2
option to
.Xr mount_nfs 8 .