compat_svr4(8)          OpenBSD System Manager's Manual         compat_svr4(8)

NAME
     compat_svr4 - setup procedure for running SVR4/iBCS2 binaries under emu-
     lation

DESCRIPTION
     OpenBSD 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:

           kernel internal data structures
           the /proc filesystem
           the ticotsord loopback rpc mechanism (nis uses this)
           sound and video interfaces
           threads (ttsession uses threads)
           the streams administrative driver

     The SVR4 compatibility feature is active for kernels compiled with the
     COMPAT_SVR4 option enabled.

     Most SVR4 programs are dynamically linked. This means that you will also
     need the shared libraries that the program depends on and the runtime
     linker. Also, you will need to create a "shadow root" directory for SVR4
     binaries on your OpenBSD system. This directory is named /emul/svr4. Any
     file operations done by SVR4 programs run under OpenBSD will look in this
     directory first. So, if a SVR4 program opens, for example, /etc/passwd,
     OpenBSD will first try to open /emul/svr4/etc/passwd, and if that does
     not exist open the 'real' /etc/passwd file. It is recommended that you
     install SVR4 packages that include configuration files, etc under
     /emul/svr4, to avoid naming conflicts with possible OpenBSD counterparts.
     Shared libraries should also be installed in the shadow tree.

     The simplest way to setup your system for SVR4 binaries is:
     1.   Make the necessary directories:

                (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}

     2.   Copy files from an SVR4 system:

                (me@svr4) cd /usr/lib
                (me@svr4) tar -cf - . | \
                     rsh openbsd 'cd /emul/svr4/usr/lib; tar -xpf -'

          If you are running OpenWindows:

                (me@svr4) cd /usr/openwin/lib
                (me@svr4) tar -cf - . | \
                     rsh openbsd 'cd /emul/svr4/usr/openwin/lib; tar -xpf -'

     3.   Setup the configuration files and devices:

                (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

     An alternative method is to mount a whole SVR4 partition in /emul/svr4
     and then override with other mounts /emul/svr4/etc and /emul/svr4/dev.

     Clearly, you cannot use a complete SVR4 /dev directory as /emul/svr4/dev,
     because other device nodes, such as /dev/null, need to be OpenBSD device
     nodes.

BUGS
     Many system calls are still not emulated. The streams emulation is incom-
     plete (socketpair does not work yet).

     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, you will see the message "svr4_getdents: dir
     offset too large for emulated program" when this happens. Currently, this
     can only happen on NFS mounted filesystems, mounted from servers that re-
     turn offsets with information in the upper 32 bits. These errors should
     rarely happen, but can be avoided by mounting this filesystem with the -2
     option to mount_nfs(8).

OpenBSD 2.9                      July 6, 1996                                2
