COMPAT_SVR4(8) OpenBSD System Manager's Manual COMPAT_SVR4(8)NAMEcompat_svr4 - setup for running SVR4/iBCS2 binaries under emulation
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
mapping of page zero to the executable for Dell SVR4 binaries
The SVR4 compatibility feature is active for kernels compiled with the
COMPAT_SVR4 option and kern.emul.svr4 sysctl(8) enabled.
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
OpenBSD system will have to be created. 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 SVR4 packages that include
configuration files, etc., be installed 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 set up the 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 OpenWindows is going to be run:
(me@svr4) cd /usr/openwin/lib
(me@svr4) tar -cf - . | \
rsh openbsd 'cd /emul/svr4/usr/openwin/lib; tar -xpf -'
3. Set up 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, a complete SVR4 /dev directory cannot be used 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
incomplete (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, 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 -2 option to mount_nfs(8).
OpenBSD 4.9 November 19, 2009 OpenBSD 4.9
