---
title: "Early Adopter's Guide to FreeBSD 5.2.1-RELEASE"
sidenav: download
---

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<div class="AUTHORGROUP"><a id="AEN4" name="AEN4"></a>
<h3 class="CORPAUTHOR">The FreeBSD Release Engineering Team</h3>
</div>

<p class="COPYRIGHT">Copyright &copy; 2002, 2003 The FreeBSD Release Engineering Team</p>

<p class="PUBDATE">$FreeBSD: src/release/doc/en_US.ISO8859-1/early-adopter/article.sgml,v
1.17 2003/12/02 05:54:35 bmah Exp $<br />
</p>

<div class="LEGALNOTICE"><a id="TRADEMARKS" name="TRADEMARKS"></a>
<p>FreeBSD is a registered trademark of Wind River Systems, Inc. This is expected to
change soon.</p>

<p>Intel, Celeron, EtherExpress, i386, i486, Itanium, Pentium, and Xeon are trademarks or
registered trademarks of Intel Corporation or its subsidiaries in the United States and
other countries.</p>

<p>Microsoft, FrontPage, MS-DOS, Outlook, Windows, Windows Media, and Windows NT are
either registered trademarks or trademarks of Microsoft Corporation in the United States
and/or other countries.</p>

<p>Sparc, Sparc64, SPARCEngine, and UltraSPARC are trademarks of SPARC International, Inc
in the United States and other countries. Products bearing SPARC trademarks are based
upon architecture developed by Sun Microsystems, Inc.</p>

<p>Many of the designations used by manufacturers and sellers to distinguish their
products are claimed as trademarks. Where those designations appear in this document, and
the FreeBSD Project was aware of the trademark claim, the designations have been followed
by the ``&trade;'' or the ``&reg;'' symbol.</p>
</div>

<div>
<div class="ABSTRACT"><a id="AEN19" name="AEN19"></a>
<p>This article describes the status of FreeBSD 5.2.1-RELEASE, from the standpoint of
users who may be new to the 5.<var class="REPLACEABLE">X</var> series of releases or to
FreeBSD in general. It presents some background information on release engineering, some
highlights of new features, and some possible drawbacks that might be faced by early
adopters. It also contains some of the future release engineering plans for the 4-STABLE
development branch and some tips on upgrading existing systems.</p>
</div>
</div>

<hr />
</div>

<div class="SECT1">
<h2 class="SECT1"><a id="INTRO" name="INTRO">1 Introduction</a></h2>

<p>FreeBSD 5.<var class="REPLACEABLE">X</var> marks the first new major version of
FreeBSD in over two years. Besides a number of new features, it also contains a number of
major developments in the underlying system architecture. Along with these advances,
however, comes a system that incorporates a tremendous amount of new and
not-widely-tested code. Compared to the existing line of 4.<var
class="REPLACEABLE">X</var> releases, the first few 5.<var class="REPLACEABLE">X</var>
releases may have regressions in areas of stability, performance, and occasionally
functionality.</p>

<p>For these reasons, the Release Engineering Team <code class="EMAIL">&#60;<a
href="mailto:re@FreeBSD.org">re@FreeBSD.org</a>&#62;</code> specifically discourages
users from updating from older FreeBSD releases to 5.2.1-RELEASE unless they are aware of
(and prepared to deal with) possible regressions in the newer releases. Specifically, for
more conservative users, we recommend running 4.<var class="REPLACEABLE">X</var> releases
(such as 4.9-RELEASE) for the near-term future. We feel that such users are probably best
served by upgrading to 5.<var class="REPLACEABLE">X</var> only after a 5-STABLE
development branch has been created; this may be around the time of 5.3-RELEASE.</p>

<p>(FreeBSD 5.<var class="REPLACEABLE">X</var> suffers from what has been described as a
``chicken and egg'' problem. The entire project has a goal of producing releases that are
as stable and reliable as possible. This stability and reliability requires widespread
testing, particularly of the system's newer features. However, getting a large number of
users to test the system, in a practical sense, means building and distributing a release
first!)</p>

<p>This article describes some of the issues involved in installing and running FreeBSD
5.2.1-RELEASE. We begin with a brief overview of the FreeBSD release process. We then
present some of the more noteworthy new features in FreeBSD 5.2.1-RELEASE, along with
some areas that may prove troublesome for unwary users. For those users choosing to
remain with 4-STABLE-based releases, we give some of the short- to medium-term plans for
this development branch. Finally, we present some notes on upgrading existing 4.<var
class="REPLACEABLE">X</var> systems to 5.2.1-RELEASE.</p>
</div>

<div class="SECT1">
<hr />
<h2 class="SECT1"><a id="RELEASE-OVERVIEW" name="RELEASE-OVERVIEW">2 An Overview of the
FreeBSD Release Process</a></h2>

<p>FreeBSD employs a model of development that relies on multiple development branches
within the source code repository. The main branch is called ``CURRENT'', and is referred
to in the CVS repository with the <var class="LITERAL">HEAD</var> tag. New features are
committed first to this branch; although this means that CURRENT is the first to see new
functionality, it also means that it occasionally suffers from breakages as new features
are added and debugged.</p>

<p>Most FreeBSD releases are made from one of several ``STABLE'' branches. Features are
only added to these branches after some amount of testing in CURRENT. At the moment, only
one STABLE branch is under active development; this branch is referred to as
``4-STABLE'', and all of the FreeBSD 4.<var class="REPLACEABLE">X</var> releases were
based on it. This branch has the tag <var class="LITERAL">RELENG_4</var> in the CVS
repository.</p>

<p>FreeBSD 5.0, 5.1, and 5.2 are based on the CURRENT branch. The first of these releases
was made after over two years of development (prior to these, the last release from HEAD
was FreeBSD 4.0, in March 2000).</p>

<p>At some point after the release of FreeBSD 5.0, a ``5-STABLE'' branch will be created
in the FreeBSD CVS repository with the branch tag <var class="LITERAL">RELENG_5</var>.
The past two stable branches (3-STABLE and 4-STABLE) were created immediately after their
respective ``dot-oh'' releases (3.0 and 4.0, respectively). In hindsight, this practice
did not give sufficient time for either CURRENT to stabilize before the new branches were
created. This in turn resulted in wasted effort porting bug fixes between branches, as
well as some architectural changes that could not be ported between branches at all.</p>

<p>Therefore, the release engineering team will only create the 5-STABLE branch in the
CVS repository after we have found a relatively stable state to use as its basis. It is
likely that there will be multiple releases in the 5.<var class="REPLACEABLE">X</var>
series before this happens; we estimate that the 5-STABLE branch will be created around
the time of 5.3-RELEASE.</p>

<p>More information on FreeBSD release engineering processes can be found on the <a
href="http://www.FreeBSD.org/releng/index.html" target="_top">Release Engineering Web
pages</a> and in the <a
href="http://www.FreeBSD.org/doc/en_US.ISO8859-1/articles/releng/index.html"
target="_top">``FreeBSD Release Engineering''</a> article. Specific issues for the
upcoming 5-STABLE development branch can be found in <a
href="http://docs.freebsd.org/doc/5.2.1-RELEASE/usr/share/doc/en_US.ISO8859-1/articles/5-roadmap/index.html"
target="_top">``The Roadmap for 5-STABLE''</a>.</p>
</div>

<div class="SECT1">
<hr />
<h2 class="SECT1"><a id="NEW" name="NEW">3 New Features</a></h2>

<p>A large attraction of FreeBSD 5.<var class="REPLACEABLE">X</var> is a number of new
features. These new features and functionality generally involve large architectural
changes that were not feasible to port back to the FreeBSD 4-STABLE development branch.
(By contrast, many self-contained enhancements, such as new device drivers or userland
utilities, have already been ported.) A brief, but not exhaustive list includes:</p>

<ul>
<li>
<p>SMPng: The ``next generation'' support for SMP machines (work in progress). Ongoing
work aims to perform fine-grained locking of various kernel subsystems to increase the
number of threads of execution that can be running in the kernel.</p>
</li>

<li>
<p>KSE: Kernel Scheduled Entities allow a single process to have multiple kernel-level
threads, similar to Scheduler Activations. The <tt class="FILENAME">libkse</tt> and <tt
class="FILENAME">libthr</tt> threading libraries make this feature available to
multi-threaded userland programs, using the <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=pthread&amp;sektion=3&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">pthread</span>(3)</span></a>
API.</p>
</li>

<li>
<p>New architectures: Support for the sparc64, ia64, and amd64 architectures, in addition
to the i386, pc98, and alpha.</p>
</li>

<li>
<p>GCC: The compiler toolchain is now based on GCC 3.3.<var class="REPLACEABLE">X</var>,
rather than GCC 2.95.<var class="REPLACEABLE">X</var>.</p>
</li>

<li>
<p>MAC: Support for extensible, loadable Mandatory Access Control policies.</p>
</li>

<li>
<p>GEOM: A flexible framework for transformations of disk I/O requests. The GBDE
experimental disk encryption facility has been developed based on GEOM.</p>
</li>

<li>
<p>FFS: The FFS filesystem now supports background <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=fsck&amp;sektion=8&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">fsck</span>(8)</span></a>
operations (for faster crash recovery) and filesystem snapshots.</p>
</li>

<li>
<p>UFS2: A new UFS2 on-disk format has been added, which supports extended per-file
attributes and larger file sizes. UFS2 is now the default format for <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=newfs&amp;sektion=8&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">newfs</span>(8)</span></a>. On all
platforms except for pc98, filesystems created from within <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=sysinstall&amp;sektion=8&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">sysinstall</span>(8)</span></a>
will use UFS2 by default.</p>
</li>

<li>
<p>Cardbus: Support for Cardbus devices.</p>
</li>

<li>
<p>Bluetooth: Support for Bluetooth devices.</p>
</li>
</ul>

<p>A more comprehensive list of new features can be found in the release notes for the
various FreeBSD 5.<var class="REPLACEABLE">X</var> releases.</p>
</div>

<div class="SECT1">
<hr />
<h2 class="SECT1"><a id="DRAWBACKS" name="DRAWBACKS">4 Drawbacks to Early
Adoption</a></h2>

<p>Along with the new features of FreeBSD 5.<var class="REPLACEABLE">X</var> come some
areas that can cause problems, or at least can lead to unexpected behavior. Generally,
these come from the fact that a number of features are works-in-progress. A partial list
of these areas of difficulty includes:</p>

<ul>
<li>
<p>A number of features are not yet finished. Examples from the feature list above
include SMPng and KSE. While suitable for testing and experimentation, these features may
not be ready for production use.</p>
</li>

<li>
<p>Because of changes in kernel data structures and ABIs/APIs, third-party binary device
drivers will require modifications to work correctly under FreeBSD 5.0. There is a
possibility of more minor ABI/API changes before the 5-STABLE branch is created,
particularly on newer machine architectures. In some (hopefully rare) cases, user-visible
structures may change, requiring recompiling of applications or reinstallation of
ports/packages.</p>
</li>

<li>
<p>Several parts of FreeBSD's base system functionality have been moved to the Ports
Collection. Notable examples include <b class="APPLICATION">Perl</b>, <b
class="APPLICATION">UUCP</b>, and most (but not all) games. While these programs are
still supported, their removal from the base system may cause some confusion.</p>
</li>

<li>
<p>Some parts of the FreeBSD base system have fallen into a state of disrepair due to a
lack of users and maintainers. These have been removed. Specific examples include the
generation of a.out-style executables, XNS networking support, and the X-10 controller
driver.</p>
</li>

<li>
<p>A number of ports and packages do not build or do not run correctly under FreeBSD
5.<var class="REPLACEABLE">X</var>, whereas they did under FreeBSD 4-STABLE. Generally
these problems are caused by compiler toolchain changes or cleanups of header files. In
some cases they are caused by changes in kernel or device support.</p>
</li>

<li>
<p>Many FreeBSD 5.<var class="REPLACEABLE">X</var> features are seeing wide exposure for
the first time. Many of these features (such as SMPng) have broad impacts on the kernel,
and it may be difficult to gauge their effects on stability and performance.</p>
</li>

<li>
<p>A certain amount of debugging and diagnostic code is still in place to help track down
problems in FreeBSD 5.<var class="REPLACEABLE">X</var>'s new features. This may cause
FreeBSD 5.<var class="REPLACEABLE">X</var> to perform more slowly than 4-STABLE.</p>
</li>

<li>
<p>Features are only added to the 4-STABLE development branch after a ``settling time''
in -CURRENT. FreeBSD 5.<var class="REPLACEABLE">X</var> does not have the stabilizing
influence of a -STABLE branch. (It is likely that the 5-STABLE development branch will be
created sometime after 5.3-RELEASE.)</p>
</li>

<li>
<p>Documentation (such as the FreeBSD <a
href="http://www.FreeBSD.org/doc/en_US.ISO8859-1/books/handbook/index.html"
target="_top">Handbook</a> and <a
href="http://www.FreeBSD.org/doc/en_US.ISO8859-1/books/faq/index.html"
target="_top">FAQ</a>) may not reflect changes recently made to FreeBSD 5.<var
class="REPLACEABLE">X</var>.</p>
</li>
</ul>

<p>Because a number of these drawbacks affect system stability, the release engineering
team recommends that more conservative sites and users stick to releases based on the
4-STABLE branch until the 5.<var class="REPLACEABLE">X</var> series is more polished.
While we believe that many initial problems with stability have been fixed, some issues
with performance are still being addressed by works-in-progress. We also note that best
common practices in system administration call for trying operating system upgrades in a
test environment before upgrading one's production, or ``mission-critical'' systems.</p>
</div>

<div class="SECT1">
<hr />
<h2 class="SECT1"><a id="PLANS-STABLE" name="PLANS-STABLE">5 Plans for the 4-STABLE
Branch</a></h2>

<p>It is important to note that even though releases are being made in the 5.<var
class="REPLACEABLE">X</var> series, support for 4.<var class="REPLACEABLE">X</var>
releases will continue for some time. Indeed, FreeBSD 4.8 was released two months after
5.0, in April 2003, followed by 4.9, in October 2003. Future releases from the 4-STABLE
branch (if any) will depend on several factors. The most important of these is the
existence and stability of the 5-STABLE branch. If CURRENT is not sufficiently stable to
allow the creation of a 5-STABLE branch, this may require and permit more releases from
the 4-STABLE branch. Until the last declared release on the 4-STABLE branch, new features
may be merged from <var class="LITERAL">HEAD</var> at the discretion of developers,
subject to existing release engineering policies.</p>

<p>To some extent, the release engineering team (as well as the developer community as a
whole) will take into account user demand for future 4-STABLE releases. This demand,
however, will need to be balanced with release engineering resources (particularly
developers' time, computing resources, and mirror archive space). We note that in
general, the FreeBSD community (both users and developers) has shown a preference for
moving forward with new features in the 5.<var class="REPLACEABLE">X</var> branch and
beyond, due to the difficulty involved in backporting (and maintaining) new functionality
in 4.<var class="REPLACEABLE">X</var>.</p>

<p>The Security Officer Team <code class="EMAIL">&#60;<a
href="mailto:security-officer@FreeBSD.org">security-officer@FreeBSD.org</a>&#62;</code>
will continue to support releases made from the 4-STABLE branch in accordance with their
published policies, which can be found on the <a
href="http://www.FreeBSD.org/security/index.html" target="_top">Security page</a> on the
FreeBSD web site. Generally, the two most recent releases from any branch will be
supported with respect to security advisories and security fixes. At its discretion, the
team may support other releases for specific issues.</p>

<p>At this point, the release engineering team has no specific plans for future releases
from the 4-STABLE development branch. It seems likely that any future releases (if any)
from this branch will be lightweight, ``point'' releases. These will probably carry
4.9.<var class="REPLACEABLE">X</var> version numbers, to indicate that they are not
intended to provide large amount of new functionality compared to 4.9-RELEASE. In
general, these releases will emphasize security fixes, bug fixes, and device driver
updates (particularly to accommodate new hardware easily supported by existing drivers).
Major new features (especially those requiring infrastructure support added in 5.<var
class="REPLACEABLE">X</var>) will probably not be added in these releases.</p>
</div>

<div class="SECT1">
<hr />
<h2 class="SECT1"><a id="UPGRADE" name="UPGRADE">6 Notes on Upgrading from FreeBSD 4.<var
class="REPLACEABLE">X</var></a></h2>

<p>For those users with existing FreeBSD systems, this section offers a few notes on
upgrading a FreeBSD 4.<var class="REPLACEABLE">X</var> system to 5.<var
class="REPLACEABLE">X</var>. As with any FreeBSD upgrade, it is crucial to read the
release notes and the errata for the version in question, as well as <tt
class="FILENAME">src/UPDATING</tt> in the case of source upgrades.</p>

<div class="SECT2">
<hr />
<h3 class="SECT2"><a id="AEN165" name="AEN165">6.1 Binary Upgrades</a></h3>

<p>Probably the most straightforward approach is that of ``backup everything, reformat,
reinstall, and restore everything''. This eliminates problems of incompatible or obsolete
executables or configuration files polluting the new system. It allows new filesystems to
be created to take advantage of new functionality (most notably, the UFS2 defaults).</p>

<p>As of this time, the binary upgrade option in <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=sysinstall&amp;sektion=8&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">sysinstall</span>(8)</span></a>
has not been well-tested for cross-major-version upgrades. Using this feature is not
recommended. In particular, a binary upgrade will leave behind a number of files that are
present in FreeBSD 4.<var class="REPLACEABLE">X</var> but not in 5.<var
class="REPLACEABLE">X</var>. These obsolete files may create some problems. Examples of
these files include old C++ headers, programs moved to the Ports Collection, or shared
libraries that have moved to support dynamically-linked root filesystem executables.</p>

<p>On the <span class="TRADEMARK">i386</span>&#8482; and pc98 platforms, a UserConfig
utility exists on 4-STABLE to allow boot-time configuration of ISA devices when booting
from installation media. Under FreeBSD 5.<var class="REPLACEABLE">X</var>, this
functionality has been replaced in part by the <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=device.hints&amp;sektion=5&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">device.hints</span>(5)</span></a>
mechanism (it allows specifying the same parameters, but with a very different
interface).</p>

<p>Floppy-based binary installations may require downloading a third, new floppy image
holding additional device drivers in kernel modules. This <tt
class="FILENAME">drivers.flp</tt> floppy image will generally be found in the same
location as the usual <tt class="FILENAME">kern.flp</tt> and <tt
class="FILENAME">mfsroot.flp</tt> floppy images.</p>

<p>CDROM-based installations on the <span class="TRADEMARK">i386</span> architecture now
use a ``no-emulation'' boot loader. This allows, among other things, the use of a <var
class="LITERAL">GENERIC</var> kernel, rather than the stripped-down kernel on the floppy
images. In theory, any system capable of booting the <span
class="TRADEMARK">Microsoft</span>&reg; <span
class="TRADEMARK">Windows&nbsp;NT</span>&reg; 4 installation CDROMs should be able to
cope with the FreeBSD 5.<var class="REPLACEABLE">X</var> CDROMs.</p>
</div>

<div class="SECT2">
<hr />
<h3 class="SECT2"><a id="AEN192" name="AEN192">6.2 Source Upgrades</a></h3>

<p>Reading <tt class="FILENAME">src/UPDATING</tt> is absolutely essential. The section
entitled ``To upgrade from 4.x-stable to current'' contains a step-by-step update
procedure. This procedure must be followed exactly, without making use of the
``shortcuts'' that some users occasionally employ.</p>
</div>

<div class="SECT2">
<hr />
<h3 class="SECT2"><a id="AEN198" name="AEN198">6.3 Common Notes</a></h3>

<p><b class="APPLICATION">Perl</b> has been removed from the base system, and should be
installed either from a pre-built package or from the Ports Collection. Building Perl as
a part of the base system created a number of difficulties which made updates
problematic. The base system utilities that used Perl have either been rewritten (if
still applicable) or discarded (if obsolete). <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=sysinstall&amp;sektion=8&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">sysinstall</span>(8)</span></a>
will now install the Perl package as a part of most distribution sets, so most users will
not notice this change.</p>

<p>It is generally possible to run old 4.<var class="REPLACEABLE">X</var> executables
under 5.<var class="REPLACEABLE">X</var>, but this requires the <tt
class="FILENAME">compat4x</tt> distribution to be installed. Using old ports may be
possible in some cases, although there are a number of known cases of backward
incompatibility. As an example, the <a
href="http://www.FreeBSD.org/cgi/url.cgi?ports/devel/gnomevfs2/pkg-descr"><tt
class="FILENAME">devel/gnomevfs2</tt></a>, <a
href="http://www.FreeBSD.org/cgi/url.cgi?ports/mail/postfix/pkg-descr"><tt
class="FILENAME">mail/postfix</tt></a>, and <a
href="http://www.FreeBSD.org/cgi/url.cgi?ports/security/cfs/pkg-descr"><tt
class="FILENAME">security/cfs</tt></a> ports need to be recompiled due to changes in the
<var class="LITERAL">statfs</var> structure.</p>

<p>When installing or upgrading over the top of an existing 4-STABLE-based system, it is
extremely important to clear out old header files in <tt
class="FILENAME">/usr/include</tt>. Renaming or moving this directory before a binary
installation or an <var class="LITERAL">installworld</var> is generally sufficient. If
this step is not taken, confusion may result (especially with C++ programs) as the
compiler may wind up using a mixture of obsolete and current header files.</p>

<p><tt class="FILENAME">MAKEDEV</tt> is no longer available, nor is it required. FreeBSD
5.<var class="REPLACEABLE">X</var> uses a device filesystem, which automatically creates
device nodes on demand. For more information, please see <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=devfs&amp;sektion=5&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">devfs</span>(5)</span></a>.</p>

<p>UFS2 is the default on-disk format for file systems created using <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=newfs&amp;sektion=8&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">newfs</span>(8)</span></a>. For
all platforms except pc98, it is also the default for file systems created using the disk
labeling screen within <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=sysinstall&amp;sektion=8&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">sysinstall</span>(8)</span></a>.
Because FreeBSD 4.<var class="REPLACEABLE">X</var> only understands UFS1 (not UFS2), disk
partitions that need to be accessed by both 5.<var class="REPLACEABLE">X</var> and 4.<var
class="REPLACEABLE">X</var> must be created with UFS1. This can be specified using the
<var class="OPTION">-O1</var> option to <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=newfs&amp;sektion=8&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">newfs</span>(8)</span></a>, or on
the disk labeling screen in <a
href="http://www.FreeBSD.org/cgi/man.cgi?query=sysinstall&amp;sektion=8&amp;manpath=FreeBSD+5.2.1-RELEASE">
<span class="CITEREFENTRY"><span class="REFENTRYTITLE">sysinstall</span>(8)</span></a>.
This situation most often arises with a a single machine that dual-boots FreeBSD 4.<var
class="REPLACEABLE">X</var> and FreeBSD 5.<var class="REPLACEABLE">X</var>. Note that
there is no way to convert file systems between the two on-disk formats (other than
backing up, re-creating the file system, and restoring).</p>
</div>
</div>

<div class="SECT1">
<hr />
<h2 class="SECT1"><a id="SUMMARY" name="SUMMARY">7 Summary</a></h2>

<p>While FreeBSD 5.2.1-RELEASE contains a number of new and exciting features, it may not
be suitable for all users at this time. In this document, we presented some background on
release engineering, some of the more notable new features of the 5.<var
class="REPLACEABLE">X</var> series, and some drawbacks to early adoption. We also
presented some future plans for the 4-STABLE development branch and some tips on
upgrading for early adopters.</p>
</div>
</div>

<hr />
<p align="center"><small>This file, and other release-related documents, can be
downloaded from <a href="ftp://ftp.FreeBSD.org/">ftp://ftp.FreeBSD.org/</a>.</small></p>

<p align="center"><small>For questions about FreeBSD, read the <a
href="http://www.FreeBSD.org/docs.html">documentation</a> before contacting &#60;<a
href="mailto:questions@FreeBSD.org">questions@FreeBSD.org</a>&#62;.</small></p>

<p align="center"><small>For questions about this documentation, e-mail &#60;<a
href="mailto:doc@FreeBSD.org">doc@FreeBSD.org</a>&#62;.</small></p>

<br />
<br />
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