.\" $NetBSD: compat_30.8,v 1.9 2011/09/13 09:16:00 wiz Exp $
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.\" by Chapman Flack.
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.Dd December 15, 2007
.Dt COMPAT_30 8
.Os
.Sh NAME
.Nm compat_30
.Nd setup procedure for backward compatibility on post-3.0 releases
.Sh SYNOPSIS
.Cd "options COMPAT_30"
.Sh DESCRIPTION
The
.Nm
module allows
.Nx
to run
.Nx 3.0
executables.
.Pp
The support is present if the kernel was built with option
.Dv COMPAT_30 .
It is not available as a loadable module.
.Pp
Static executables typically need no additional setup.
Dynamic binaries may require shared libraries whose major version
number changed since
.Nx 3.0 ,
which are listed below.
A shadow directory under
.Pa /emul
is not used; the libraries can be obtained from a
.Nx 3.0
distribution and installed in the original directories shown,
as the major version number in the file name will prevent conflicts.
If an upgrade installation from
.Nx 3.0
has been done and these libraries are still present, nothing more need
be done.
.Ss Libraries needed from 3.0
.Bl -item
.It
.Pa /lib/libcrypto.so.2.1
.Pa /lib/libcrypto.so.2
.It
.Pa /usr/lib/libcrypto.so.2.1
.Pa /usr/lib/libcrypto.so.2
.It
.Pa /lib/libevent.so.0.2
.Pa /lib/libevent.so.0
.It
.Pa /usr/lib/libevent.so.0.2
.Pa /usr/lib/libevent.so.0
.It
.Pa /usr/lib/libg2c.so.2.0
.Pa /usr/lib/libg2c.so.2
.It
.Pa /usr/lib/libkadm.so.5.0
.Pa /usr/lib/libkadm.so.5
.It
.Pa /usr/lib/libkafs.so.6.0
.Pa /usr/lib/libkafs.so.6
.It
.Pa /usr/lib/libkdb.so.5.0
.Pa /usr/lib/libkdb.so.5
.It
.Pa /usr/lib/libkrb5.so.19.1
.Pa /usr/lib/libkrb5.so.19
.It
.Pa /usr/lib/libkrb.so.6.0
.Pa /usr/lib/libkrb.so.6
.It
.Pa /usr/lib/libkstream.so.2.0
.Pa /usr/lib/libkstream.so.2
.It
.Pa /usr/lib/libmagic.so.0.1
.Pa /usr/lib/libmagic.so.0
.It
.Pa /usr/lib/libpcap.so.1.4
.Pa /usr/lib/libpcap.so.1
.It
.Pa /lib/libradius.so.0.0
.Pa /lib/libradius.so.0
.It
.Pa /usr/lib/libradius.so.0.0
.Pa /usr/lib/libradius.so.0
.It
.Pa /usr/lib/libssh.so.1.0
.Pa /usr/lib/libssh.so.1
.It
.Pa /usr/lib/libssl.so.3.0
.Pa /usr/lib/libssl.so.3
.It
.Pa /usr/lib/libstdc++.so.5.0
.Pa /usr/lib/libstdc++.so.5
.\" .It
.\" .Pa libtelnet lives where?
.It
.Pa /lib/libz.so.0.4
.Pa /lib/libz.so.0
.It
.Pa /usr/lib/libz.so.0.4
.Pa /usr/lib/libz.so.0
.It
.Pa /usr/lib/libamu.so.2.1
.Pa /usr/lib/libamu.so.2
.El
.Sh IMPLEMENTATION NOTES
.Dv COMPAT_30
enables the
.Nx 3.0
versions of the following system calls, whose syscall numbers and
argument structures were changed after the 3.0 release to accommodate
64-bit filesystems:
.Xr fhstat 2 ,
.Xr fstat 2 ,
.Xr getdents 2 ,
.Xr lstat 2 ,
.Xr stat 2 .
.Pp
The filehandle structure (formerly
.Vt fhandle_t )
was made opaque to userland and variable-sized.
A
.Fa fh_size
argument was added to related syscalls:
.Xr fhstat 2 ,
.Xr fhstatvfs 2 ,
.Xr fhstatvfs1 2 ,
.Xr fhopen 2 ,
.Xr getfh 2 .
This changes the API and ABI of those syscalls,
.Dv COMPAT_30
enables binary compatibility with the old ABI.
Source compatibility is not provided, as use of those syscalls is
supposed to be rare.
.Pp
The error code from the
.Xr socket 2
syscall changed from
.Er EPROTONOSUPPORT
to
.Er EAFNOSUPPORT
in the case of an unsupported address family.
.Dv COMPAT_30
enables binary compatibility with the old ABI.
Source compatiblility is not provided.
.Pp
The
.Vt struct ntptimeval
used by
.Xr ntp_gettime 2
changed with the implementation of timecounters.
.Sh SEE ALSO
.Xr config 1 ,
.Xr fhstat 2 ,
.Xr fstat 2 ,
.Xr getdents 2 ,
.Xr lstat 2 ,
.Xr stat 2 ,
.Xr options 4
.Sh HISTORY
.Nx
offers back-compatibility options back to
.Nx 0.9 ,
but the first to be documented with a manual page is
.Nm .
.Sh BUGS
The compatible
.Xr getdents 2
is unable to see directory entries beneath the top layer of a union,
even though the real 3.0
.Fn getdents
did not have that problem.
.Sh SECURITY CONSIDERATIONS
Programs with security impact that receive incorrect directory contents
from
.Fn getdents
may behave improperly, as when they are unable to find, or find the wrong
versions of, important files.