NAME    [Toc]    [Back]

     compat_aout - setup for running a.out  OpenBSD  binaries  on
ELF systems

DESCRIPTION    [Toc]    [Back]

     OpenBSD  supports  running legacy a.out binaries.  This only
applies to
     i386 systems for now.  Most programs should work.

     The a.out compatibility feature is active for  kernels  compiled with the
     COMPAT_AOUT option and kern.emul.aout sysctl(8) enabled.

     A  lot  of programs are dynamically linked.  This means that
the shared libraries
 that the programs depend on and the  runtime  linker
are also needed.
  A "shadow root" directory for these files on the OpenBSD system will
     have to be created.  This directory  is  named  /emul/a.out.
Selected file
     operations  done  by legacy a.out programs run under OpenBSD
will look in
     this directory first.

   Setting up shared libraries    [Toc]    [Back]
     Up until OpenBSD 3.3, programs were  using  the  a.out  file
format.  When
     migrating  to  a  current  ELF system, some old binaries may
still be used.
     Before installing a current system, all the necessary shared
libraries in
     the  /usr/lib,  /usr/X11R6/lib, /usr/local/lib and the a.out
dynamic linker
     system,   namely   /usr/libexec/ld.so,   /usr/bin/ldd,   and
/sbin/ldconfig
     should be copied to the corresponding location in the shadow
tree.
     (e.g., copy /sbin/ldconfig into  /emul/a.out/sbin/ldconfig).
The directory
 /emul/a.out/var/run should also be created.

     Before  running a.out binaries, the ld.so cache must be prepared, by running
 /emul/a.out/sbin/ldconfig.

     Once everything is set up properly, a.out programs will look
for shared
     libraries  under  /emul/a.out  and ELF programs will not see
the a.out
     shared libraries.

OpenBSD     3.6                           June      25,      2003