COMPAT_IBCS2(8)         OpenBSD System Manager's Manual        COMPAT_IBCS2(8)

NAME
     compat_ibcs2 - setup procedure for running iBCS2 binaries under emulation

DESCRIPTION
     OpenBSD supports running Intel Binary Compatibility Standard 2 (iBCS2)
     binaries.  This only applies to i386 systems for now.  Binaries are sup-
     ported from SCO UNIX and other systems derived from UNIX System V Release
     3.  iBCS2 support is only well tested using SCO binaries.  XENIX binaries
     are also supported although not as well tested.  SVR4 binaries are sup-
     ported by the COMPAT_SVR4 option.

     iBCS2 supports COFF, ELF, and x.out (XENIX) binary formats.  Binaries
     from SCO OpenServer (version 5.x) are the only ELF binaries that have
     been tested.  Most programs should work, but not ones that use or depend
     on:

           kernel internal data structures
           STREAMS drivers (other than TCP/IP sockets)
           local X displays (uses a STREAMS pipe)
           virtual 8086 mode

     The iBCS2 compatibility feature is active for kernels compiled with the
     COMPAT_IBCS2 option enabled.  If support for iBCS2 ELF executables is de-
     sired, the EXEC_ELF32 option should be enabled in addition to
     COMPAT_IBCS2.

     Many COFF-format programs and most ELF-format programs are dynamically
     linked.  This means that you will also need the shared libraries that the
     program depends on.  Also, you will need to create a "shadow root" direc-
     tory for iBCS2 binaries on your OpenBSD system.  This directory is named
     /emul/ibcs2.  Any file operations done by iBCS2 programs run under OpenB-
     SD will look in this directory first.  So, if an iBCS2 program opens, for
     example, /etc/passwd, OpenBSD will first try to open
     /emul/ibcs2/etc/passwd, and if that does not exist open the 'real'
     /etc/passwd file.  It is recommended that you install iBCS2 packages that
     include configuration files, etc. under /emul/ibcs2, to avoid naming con-
     flicts with possible OpenBSD counterparts.  Shared libraries should also
     be installed in the shadow tree.

     Generally, you will need to look for the shared libraries that iBCS2 bi-
     naries depend on only the first few times that you install an iBCS2 pro-
     gram on your OpenBSD system.  After a while, you will have a sufficient
     set of iBCS2 shared libraries on your system to be able to run newly im-
     ported iBCS2 binaries without any extra work.


   Setting up shared libraries
     How to get to know which shared libraries iBCS2 binaries need, and where
     to get them?  Depending on the file type of the executable, there are
     different possibilities (when following these instructions: you will need
     to be root on your OpenBSD system to do the necessary installation
     steps).

     1. COFF binaries
          You can simply copy all of the available shared libraries since they
          are fairly small in size.  The COFF shared libraries are typically
          found in /shlib and can be obtained from the following sources:

          SCO UNIX version 3.x (aka ODT)
          SCO UNIX version 5.x (aka OpenServer)
          SCO UnixWare
          Many versions of SVR4.2/x86

          After copying the shared libraries, you should have at least the
          following files on your system:

          /emul/ibcs2/shlib/libc_s
          /emul/ibcs2/shlib/libnsl_s
          /emul/ibcs2/shlib/protlib_s

     2. ELF binaries
          You can simply copy all of the available shared libraries from the
          source system or distribution or use the `ldd-elf' program (in de-
          velopment) to determine the libraries required by a specific binary.

          After copying the shared libraries, you should have at least the
          following files on your system:

          /emul/ibcs2/usr/lib/libc.so.1
          /emul/ibcs2/usr/lib/libcrypt.so
          /emul/ibcs2/usr/lib/libndbm.so
          /emul/ibcs2/usr/lib/libsocket.so.1

     If you don't have access to a SCO system, you will need to get the extra
     files you need from a SCO distribution.  As of January 1998, SCO sells a
     copy of SCO OpenServer (iBCS2) and/or SCO UnixWare (SVR4) for person-
     al/non-commercial use for only the cost of shipping (about $20US).  The
     distribution comes on an ISO9660-format CDROM which can be mounted and
     used to copy the necessary files.

BUGS
     The information about SCO distributions may become outdated.

     Attempting to a use a nameserver on the local host does not currently
     work due to an absurd shortcut taken by the iBCS2 network code (remember
     that there are no kernel sockets).

     16/32/64 bit offsets may not be handled correctly in all cases.

OpenBSD 3.0                    February 8, 1998                              2
