Build PIM by default as part of the IPv4 multicast forwarding path.

[FreeBSD/FreeBSD.git] / UPDATING

Updating Information for FreeBSD current users

This file is maintained and copyrighted by M. Warner Losh
<imp@village.org>.  See end of file for further details.  For commonly
done items, please see the COMMON ITEMS: section later in the file.

Items affecting the ports and packages system can be found in
/usr/ports/UPDATING.  Please read that file before running
portupgrade.

NOTE TO PEOPLE WHO THINK THAT FreeBSD 7.x IS SLOW:
        FreeBSD 7.x has many debugging features turned on, in
        both the kernel and userland.  These features attempt to detect
        incorrect use of system primitives, and encourage loud failure
        through extra sanity checking and fail stop semantics.  They
        also substantially impact system performance.  If you want to
        do performance measurement, benchmarking, and optimization,
        you'll want to turn them off.  This includes various WITNESS-
        related kernel options, INVARIANTS, malloc debugging flags
        in userland, and various verbose features in the kernel.  Many
        developers choose to disable these features on build machines
        to maximize performance.

20070210:
        PIM has been turned on by default in the IPv4 multicast
        routing code. The kernel option 'PIM' has now been removed.
        PIM is now built by default if option 'MROUTING' is specified.
        It may now be loaded into GENERIC kernels by loading the
        ip_mroute.ko module.

20070207:
        Support for IPIP tunnels (VIFF_TUNNEL) in IPv4 multicast routing
        has been removed. Its functionality may be achieved by explicitly
        configuring gif(4) interfaces and using the 'phyint' keyword in
        mrouted.conf.
        XORP does not support source-routed IPv4 multicast tunnels nor the
        integrated IPIP tunneling, therefore it is not affected by this
        change. The __FreeBSD_version macro has been bumped to 700030.

20061221:
        Support for PCI Message Signalled Interrupts has been
        re-enabled in the bge driver, only for those chips which are
        believed to support it properly.  If there are any problems,
        MSI can be disabled completely by setting the
        'hw.pci.enable_msi' and 'hw.pci.enable_msix' tunables to 0
        in the loader.

20061214:
        Support for PCI Message Signalled Interrupts has been
        disabled again in the bge driver.  Many revisions of the
        hardware fail to support it properly.  Support can be
        re-enabled by removing the #define of BGE_DISABLE_MSI in
        "src/sys/dev/bge/if_bge.c".

20061214:
        Support for PCI Message Signalled Interrupts has been added
        to the bge driver.  If there are any problems, MSI can be
        disabled completely by setting the 'hw.pci.enable_msi' and
        'hw.pci.enable_msix' tunables to 0 in the loader.

20061205:
        The removal of several facets of the experimental Threading 
        system from the kernel means that the proc and thread structures 
        have changed quite a bit. I suggest all kernel modules that might
        reference these structures be recompiled.. Especially the
        linux module.

20061126:
        Sound infrastructure has been updated with various fixes and
        improvements. Most of the changes are pretty much transparent,
        with exceptions of followings:
        1) All sound driver specific sysctls (hw.snd.pcm%d.*) have been
           moved to their own dev sysctl nodes, for example:
                hw.snd.pcm0.vchans -> dev.pcm.0.vchans
        2) /dev/dspr%d.%d has been deprecated. Each channel now has its
           own chardev in the form of "dsp%d.<function>%d", where <function>
           is p = playback, r = record and v = virtual, respectively. Users
           are encouraged to use these devs instead of (old) "/dev/dsp%d.%d".
           This does not affect those who are using "/dev/dsp".

20061122:
        The following binaries have been disconnected from the build:
        mount_devfs, mount_ext2fs, mount_fdescfs, mount_procfs, mount_linprocfs,
        and mount_std.  The functionality of these programs has been
        moved into the mount program.  For example, to mount a devfs
        filesystem, instead of using mount_devfs, use: "mount -t devfs".
        This does not affect entries in /etc/fstab, since entries in
        /etc/fstab are always processed with "mount -t fstype".

20061113:
        Support for PCI Message Signalled Interrupts on i386 and amd64
        has been added to the kernel and various drivers will soon be
        updated to use MSI when it is available.  If there are any problems,
        MSI can be disabled completely by setting the 'hw.pci.enable_msi'
        and 'hw.pci.enable_msix' tunables to 0 in the loader.

20061110:
        The MUTEX_PROFILING option has been renamed to LOCK_PROFILING.
        The lockmgr object layout has been changed as a result of having
        a lock_object embedded in it. As a consequence all file system
        kernel modules must be re-compiled. The mutex profiling man page 
        has not yet been updated to reflect this change.

20061026:
        KSE in the kernel has now been made optional and turned on by
        default. Use 'nooption KSE' in your kernel config to turn it
        off. All kernel modules *must* be recompiled after this change.
        There-after, modules from a KSE kernel should be compatible with
        modules from a NOKSE kernel due to the temporary padding fields
        added to 'struct proc'.

20060929:
        mrouted and its utilities have been removed from the base system.

20060927:
        Some ioctl(2) command codes have changed.  Full backward ABI
        compatibility is provided if the "options COMPAT_FREEBSD6" is
        present in the kernel configuration file.  Make sure to add
        this option to your kernel config file, or recompile X.Org
        and the rest of ports; otherwise they may refuse to work.

20060924:
        tcpslice has been removed from the base system.

20060913:
        The sizes of struct tcpcb (and struct xtcpcb) have changed due to
        the rewrite of TCP syncookies.  Tools like netstat, sockstat, and
        systat needs to be rebuilt.

20060903:
        libpcap updated to v0.9.4 and tcpdump to v3.9.4

20060816:
        The IPFIREWALL_FORWARD_EXTENDED option is gone and the behaviour
        for IPFIREWALL_FORWARD is now as it was before when it was first
        committed and for years after. The behaviour is now ON.

20060725:
        enigma(1)/crypt(1) utility has been changed on 64 bit architectures.
        Now it can decrypt files created from different architectures.
        Unfortunately, it is no longer able to decrypt a cipher text
        generated with an older version on 64 bit architectures.
        If you have such a file, you need old utility to decrypt it.

20060709:
        The interface version of the i4b kernel part has changed. So
        after updating the kernel sources and compiling a new kernel,
        the i4b user space tools in "/usr/src/usr.sbin/i4b" must also
        be rebuilt, and vice versa.
 
20060627:
        The XBOX kernel now defaults to the nfe(4) driver instead of
        the nve(4) driver. Please update your configuration
        accordingly.

20060514:
        The i386-only lnc(4) driver for the AMD Am7900 LANCE and Am79C9xx
        PCnet family of NICs has been removed. The new le(4) driver serves
        as an equivalent but cross-platform replacement with the pcn(4)
        driver still providing performance-optimized support for the subset
        of AMD Am79C971 PCnet-FAST and greater chips as before.

20060511:
        The machdep.* sysctls and the adjkerntz utility have been
        modified a bit.  The new adjkerntz utility uses the new
        sysctl names and sysctlbyname() calls, so it may be impossible
        to run an old /sbin/adjkerntz utility in single-user mode
        with a new kernel.  Replace the `adjkerntz -i' step before
        `make installworld' with:

            /usr/obj/usr/src/sbin/adjkerntz/adjkerntz -i

        and proceed as usual with the rest of the installworld-stage
        steps.  Otherwise, you risk installing binaries with their
        timestamp set several hours in the future, especially if
        you are running with local time set to GMT+X hours.

20060412:
        The ip6fw utility has been removed.  The behavior provided by
        ip6fw has been in ipfw2 for a good while and the rc.d scripts
        have been updated to deal with it.  There are some rules that
        might not migrate cleanly.  Use rc.firewall6 as a template to
        rewrite rules.

20060428:
        The puc(4) driver has been overhauled. The ebus(4) and sbus(4)
        attachments have been removed. Make sure to configure scc(4)
        on sparc64. Note also that by default puc(4) will use uart(4)
        and not sio(4) for serial ports because interrupt handling has
        been optimized for multi-port serial cards and only uart(4)
        implements the interface to support it.

20060330:
        The scc(4) driver replaces puc(4) for Serial Communications
        Controllers (SCCs) like the Siemens SAB82532 and the Zilog
        Z8530. On sparc64, it is advised to add scc(4) to the kernel
        configuration to make sure that the serial ports remain
        functional.

20060317:
        Most world/kernel related NO_* build options changed names.
        New knobs have common prefixes WITHOUT_*/WITH_* (modelled
        after FreeBSD ports) and should be set in /etc/src.conf
        (the src.conf(5) manpage is provided).  Full backwards
        compatibility is maintained for the time being though it's
        highly recommended to start moving old options out of the
        system-wide /etc/make.conf file into the new /etc/src.conf
        while also properly renaming them.  More conversions will
        likely follow.  Posting to current@:

        http://lists.freebsd.org/pipermail/freebsd-current/2006-March/061725.html

20060305:
        The NETSMBCRYPTO kernel option has been retired because its
        functionality is always included in NETSMB and smbfs.ko now.

20060303:
        The TDFX_LINUX kernel option was retired and replaced by the
        tdfx_linux device.  The latter can be loaded as the 3dfx_linux.ko
        kernel module.  Loading it alone should suffice to get 3dfx support
        for Linux apps because it will pull in 3dfx.ko and linux.ko through
        its dependencies.

20060204:
        The 'audit' group was added to support the new auditing functionality
        in the base system.  Be sure to follow the directions for updating,
        including the requirement to run mergemaster -p.

20060201:
        The kernel ABI to file system modules was changed on i386.
        Please make sure that your kernel and modules are in sync.
        
20060118:
        This actually occured some time ago, but installing the kernel
        now also installs a bunch of symbol files for the kernel modules.
        This increases the size of /boot/kernel to about 67Mbytes. You
        will need twice this if you will eventually back this up to kernel.old
        on your next install.
        If you have a shortage of room in your root partition, you should add
        -DINSTALL_NODEBUG to your make arguments or add INSTALL_NODEBUG="yes"
        to your /etc/make.conf.

20060113:
        libc's malloc implementation has been replaced.  This change has the
        potential to uncover application bugs that previously went unnoticed.
        See the malloc(3) manual page for more details.

20060112:
        The generic netgraph(4) cookie has been changed. If you upgrade
        kernel passing this point, you also need to upgrade userland
        and netgraph(4) utilities like ports/net/mpd or ports/net/mpd4.

20060106:
        si(4)'s device files now contain the unit number.
        Uses of {cua,tty}A[0-9a-f] should be replaced by {cua,tty}A0[0-9a-f].

20060106:
        The kernel ABI was mostly destroyed due to a change in the size
        of struct lock_object which is nested in other structures such
        as mutexes which are nested in all sorts of other structures.
        Make sure your kernel and modules are in sync.

20051231:
        The page coloring algorithm in the VM subsystem was converted
        from tuning with kernel options to autotuning. Please remove
        any PQ_* option except PQ_NOOPT from your kernel config.

20051211:
        The net80211-related tools in the tools/tools/ath directory
        have been moved to tools/tools/net80211 and renamed with a
        "wlan" prefix.  Scripts that use them should be adjusted
        accordingly.

20051202:
        Scripts in the local_startup directories (as defined in
        /etc/defaults/rc.conf) that have the new rc.d semantics will
        now be run as part of the base system rcorder. If there are
        errors or problems with one of these local scripts, it could
        cause boot problems. If you encounter such problems, boot in
        single user mode, remove that script from the */rc.d directory.
        Please report the problem to the port's maintainer, and the
        freebsd-ports@freebsd.org mailing list.

20051129:
        The nodev mount option was deprecated in RELENG_6 (where it
        was a no-op), and is now unsupported.  If you have nodev or dev listed
        in /etc/fstab, remove it, otherwise it will result in a mount error.

20051129:
        ABI between ipfw(4) and ipfw(8) has been changed. You need
        to rebuild ipfw(8) when rebuilding kernel.

20051108:
        rp(4)'s device files now contain the unit number.
        Uses of {cua,tty}R[0-9a-f] should be replaced by {cua,tty}R0[0-9a-f].

20051029:
        /etc/rc.d/ppp-user has been renamed to /etc/rc.d/ppp.
        Its /etc/rc.conf.d configuration file has been `ppp' from
        the beginning, and hence there is no need to touch it.

20051014:
        Now most modules get their build-time options from the kernel
        configuration file.  A few modules still have fixed options
        due to their non-conformant implementation, but they will be
        corrected eventually.  You may need to review the options of
        the modules in use, explicitly specify the non-default options
        in the kernel configuration file, and rebuild the kernel and
        modules afterwards.

20051001:
        kern.polling.enable sysctl MIB is now deprecated. Use ifconfig(8)
        to turn polling(4) on your interfaces.

20050927:
        The old bridge(4) implementation was retired.  The new
        if_bridge(4) serves as a full functional replacement.

20050722:
        The ai_addrlen of a struct addrinfo was changed to a socklen_t
        to conform to POSIX-2001.  This change broke an ABI
        compatibility on 64 bit architecture.  You have to recompile
        userland programs that use getaddrinfo(3) on 64 bit
        architecture.

20050711:
        RELENG_6 branched here.

20050629:
        The pccard_ifconfig rc.conf variable has been removed and a new
        variable, ifconfig_DEFAULT has been introduced.  Unlike
        pccard_ifconfig, ifconfig_DEFAULT applies to ALL interfaces that
        do not have ifconfig_ifn entries rather than just those in
        removable_interfaces.

20050616:
        Some previous versions of PAM have permitted the use of
        non-absolute paths in /etc/pam.conf or /etc/pam.d/* when referring
        to third party PAM modules in /usr/local/lib.  A change has been
        made to require the use of absolute paths in order to avoid
        ambiguity and dependence on library path configuration, which may
        affect existing configurations.

20050610:
        Major changes to network interface API.  All drivers must be
        recompiled.  Drivers not in the base system will need to be
        updated to the new APIs.

20050609:
        Changes were made to kinfo_proc in sys/user.h.  Please recompile
        userland, or commands like `fstat', `pkill', `ps', `top' and `w'
        will not behave correctly.

        The API and ABI for hwpmc(4) have changed with the addition
        of sampling support.  Please recompile lib/libpmc(3) and
        usr.sbin/{pmcstat,pmccontrol}.

20050606:
        The OpenBSD dhclient was imported in place of the ISC dhclient
        and the network interface configuration scripts were updated
        accordingly.  If you use DHCP to configure your interfaces, you
        must now run devd.  Also, DNS updating was lost so you will need
        to find a workaround if you use this feature.

        The '_dhcp' user was added to support the OpenBSD dhclient.  Be
        sure to run mergemaster -p (like you are supposed to do every time
        anyway).

20050605:
        if_bridge was added to the tree. This has changed struct ifnet.
        Please recompile userland and all network related modules.

20050603:
        The n_net of a struct netent was changed to an uint32_t, and
        1st argument of getnetbyaddr() was changed to an uint32_t, to
        conform to POSIX-2001.  These changes broke an ABI
        compatibility on 64 bit architecture.  With these changes,
        shlib major of libpcap was bumped.  You have to recompile
        userland programs that use getnetbyaddr(3), getnetbyname(3),
        getnetent(3) and/or libpcap on 64 bit architecture.

20050528:
        Kernel parsing of extra options on '#!' first lines of shell
        scripts has changed.  Lines with multiple options likely will
        fail after this date.  For full details, please see
                http://people.freebsd.org/~gad/Updating-20050528.txt

20050503:
        The packet filter (pf) code has been updated to OpenBSD 3.7
        Please note the changed anchor syntax and the fact that
        authpf(8) now needs a mounted fdescfs(5) to function.

20050415:
        The NO_MIXED_MODE kernel option has been removed from the i386
        amd64 platforms as its use has been superceded by the new local
        APIC timer code.  Any kernel config files containing this option
        should be updated.

20050227:
        The on-disk format of LC_CTYPE files was changed to be machine
        independent.  Please make sure NOT to use NO_CLEAN buildworld
        when crossing this point. Crossing this point also requires
        recompile or reinstall of all locale depended packages.

20050225:
        The ifi_epoch member of struct if_data has been changed to
        contain the uptime at which the interface was created or the
        statistics zeroed rather then the wall clock time because
        wallclock time may go backwards.  This should have no impact
        unless an snmp implementation is using this value (I know of
        none at this point.)

20050224:
        The acpi_perf and acpi_throttle drivers are now part of the
        acpi(4) main module.  They are no longer built separately.

20050223:
        The layout of struct image_params has changed. You have to
        recompile all compatibility modules (linux, svr4, etc) for use
        with the new kernel.

20050223:
        The p4tcc driver has been merged into cpufreq(4).  This makes
        "options CPU_ENABLE_TCC" obsolete.  Please load cpufreq.ko or
        compile in "device cpufreq" to restore this functionality.

20050220:
        The responsibility of recomputing the file system summary of
        a SoftUpdates-enabled dirty volume has been transferred to the
        background fsck.  A rebuild of fsck(8) utility is recommended
        if you have updated the kernel.

        To get the old behavior (recompute file system summary at mount
        time), you can set vfs.ffs.compute_summary_at_mount=1 before
        mounting the new volume.

20050206:
        The cpufreq import is complete.  As part of this, the sysctls for
        acpi(4) throttling have been removed.  The power_profile script
        has been updated, so you can use performance/economy_cpu_freq in
        rc.conf(5) to set AC on/offline cpu frequencies.

20050206:
        NG_VERSION has been increased. Recompiling kernel (or ng_socket.ko)
        requires recompiling libnetgraph and userland netgraph utilities.

20050114:
        Support for abbreviated forms of a number of ipfw options is
        now deprecated.  Warnings are printed to stderr indicating the
        correct full form when a match occurs.  Some abbreviations may
        be supported at a later date based on user feedback.  To be
        considered for support, abbreviations must be in use prior to
        this commit and unlikely to be confused with current key words.

20041221:
        By a popular demand, a lot of NOFOO options were renamed
        to NO_FOO (see bsd.compat.mk for a full list).  The old
        spellings are still supported, but will cause annoying
        warnings on stderr.  Make sure you upgrade properly (see
        the COMMON ITEMS: section later in this file).

20041219:
        Auto-loading of ancillary wlan modules such as wlan_wep has
        been temporarily disabled; you need to statically configure
        the modules you need into your kernel or explicitly load them
        prior to use.  Specifically, if you intend to use WEP encryption
        with an 802.11 device load/configure wlan_wep; if you want to
        use WPA with the ath driver load/configure wlan_tkip, wlan_ccmp,
        and wlan_xauth as required.

20041213:
        The behaviour of ppp(8) has changed slightly.  If lqr is enabled
        (``enable lqr''), older versions would revert to LCP ECHO mode on
        negotiation failure.  Now, ``enable echo'' is required for this
        behaviour.  The ppp version number has been bumped to 3.4.2 to
        reflect the change.

20041201:
        The wlan support has been updated to split the crypto support
        into separate modules.  For static WEP you must configure the
        wlan_wep module in your system or build and install the module
        in place where it can be loaded (the kernel will auto-load
        the module when a wep key is configured).

20041201:
        The ath driver has been updated to split the tx rate control
        algorithm into a separate module.  You need to include either
        ath_rate_onoe or ath_rate_amrr when configuring the kernel.

20041116:
        Support for systems with an 80386 CPU has been removed.  Please
        use FreeBSD 5.x or earlier on systems with an 80386.

20041110:
        We have had a hack which would mount the root filesystem
        R/W if the device were named 'md*'.  As part of the vnode
        work I'm doing I have had to remove this hack.  People
        building systems which use preloaded MD root filesystems
        may need to insert a "/sbin/mount -u -o rw /dev/md0 /" in
        their /etc/rc scripts.

20041104:
        FreeBSD 5.3 shipped here.

20041102:
        The size of struct tcpcb has changed again due to the removal
        of RFC1644 T/TCP.  You have to recompile userland programs that
        read kmem for tcp sockets directly (netstat, sockstat, etc.)

20041022:
        The size of struct tcpcb has changed.  You have to recompile
        userland programs that read kmem for tcp sockets directly
        (netstat, sockstat, etc.)

20041016:
        RELENG_5 branched here.  For older entries, please see updating
        in the RELENG_5 branch.

COMMON ITEMS:

        General Notes
        -------------
        Avoid using make -j when upgrading.  From time to time in the
        past there have been problems using -j with buildworld and/or
        installworld.  This is especially true when upgrading between
        "distant" versions (eg one that cross a major release boundary
        or several minor releases, or when several months have passed
        on the -current branch).

        Sometimes, obscure build problems are the result of environment
        poisoning.  This can happen because the make utility reads its
        environment when searching for values for global variables.
        To run your build attempts in an "environmental clean room",
        prefix all make commands with 'env -i '.  See the env(1) manual
        page for more details.

        When upgrading from one major version to another it is generally
        best to upgrade to the latest code in the currently installed branch
        first, then do an upgrade to the new branch. This is the best-tested
        upgrade path, and has the highest probability of being successful.
        Please try this approach before reporting problems with a major
        version upgrade.

        To build a kernel
        -----------------
        If you are updating from a prior version of FreeBSD (even one just
        a few days old), you should follow this procedure.  It is the most
        failsafe as it uses a /usr/obj tree with a fresh mini-buildworld,

        make kernel-toolchain
        make -DALWAYS_CHECK_MAKE buildkernel KERNCONF=YOUR_KERNEL_HERE
        make -DALWAYS_CHECK_MAKE installkernel KERNCONF=YOUR_KERNEL_HERE

        To test a kernel once
        ---------------------
        If you just want to boot a kernel once (because you are not sure
        if it works, or if you want to boot a known bad kernel to provide
        debugging information) run
        make installkernel KERNCONF=YOUR_KERNEL_HERE KODIR=/boot/testkernel
        nextboot -k testkernel

        To just build a kernel when you know that it won't mess you up
        --------------------------------------------------------------
        This assumes you are already running a 5.X system.  Replace
        ${arch} with the architecture of your machine (e.g. "i386",
        "alpha", "amd64", "ia64", "pc98", "sparc64", etc).

        cd src/sys/${arch}/conf
        config KERNEL_NAME_HERE
        cd ../compile/KERNEL_NAME_HERE
        make depend
        make
        make install

        If this fails, go to the "To build a kernel" section.

        To rebuild everything and install it on the current system.
        -----------------------------------------------------------
        # Note: sometimes if you are running current you gotta do more than
        # is listed here if you are upgrading from a really old current.

        <make sure you have good level 0 dumps>
        make buildworld
        make kernel KERNCONF=YOUR_KERNEL_HERE
                                                        [1]
        <reboot in single user>                         [3]
        mergemaster -p                                  [5]
        make installworld
        make delete-old
        mergemaster                                     [4]
        <reboot>


        To cross-install current onto a separate partition
        --------------------------------------------------
        # In this approach we use a separate partition to hold
        # current's root, 'usr', and 'var' directories.   A partition
        # holding "/", "/usr" and "/var" should be about 2GB in
        # size.

        <make sure you have good level 0 dumps>
        <boot into -stable>
        make buildworld
        make buildkernel KERNCONF=YOUR_KERNEL_HERE
        <maybe newfs current's root partition>
        <mount current's root partition on directory ${CURRENT_ROOT}>
        make installworld DESTDIR=${CURRENT_ROOT}
        make distribution DESTDIR=${CURRENT_ROOT} # if newfs'd
        make installkernel KERNCONF=YOUR_KERNEL_HERE DESTDIR=${CURRENT_ROOT}
        cp /etc/fstab ${CURRENT_ROOT}/etc/fstab                    # if newfs'd
        <edit ${CURRENT_ROOT}/etc/fstab to mount "/" from the correct partition>
        <reboot into current>
        <do a "native" rebuild/install as described in the previous section>
        <maybe install compatibility libraries from src/lib/compat>
        <reboot>


        To upgrade in-place from 5.x-stable to current
        ----------------------------------------------
        <make sure you have good level 0 dumps>
        make buildworld                                 [9]
        make kernel KERNCONF=YOUR_KERNEL_HERE           [8]
                                                        [1]
        <reboot in single user>                         [3]
        mergemaster -p                                  [5]
        make installworld
        make delete-old
        mergemaster -i                                  [4]
        <reboot>

        Make sure that you've read the UPDATING file to understand the
        tweaks to various things you need.  At this point in the life
        cycle of current, things change often and you are on your own
        to cope.  The defaults can also change, so please read ALL of
        the UPDATING entries.

        Also, if you are tracking -current, you must be subscribed to
        freebsd-current@freebsd.org.  Make sure that before you update
        your sources that you have read and understood all the recent
        messages there.  If in doubt, please track -stable which has
        much fewer pitfalls.

        [1] If you have third party modules, such as vmware, you
        should disable them at this point so they don't crash your
        system on reboot.

        [3] From the bootblocks, boot -s, and then do
                fsck -p
                mount -u /
                mount -a
                cd src
                adjkerntz -i            # if CMOS is wall time
        Also, when doing a major release upgrade, it is required that
        you boot into single user mode to do the installworld.

        [4] Note: This step is non-optional.  Failure to do this step
        can result in a significant reduction in the functionality of the
        system.  Attempting to do it by hand is not recommended and those
        that pursue this avenue should read this file carefully, as well
        as the archives of freebsd-current and freebsd-hackers mailing lists
        for potential gotchas.

        [5] Usually this step is a noop.  However, from time to time
        you may need to do this if you get unknown user in the following
        step.  It never hurts to do it all the time.  You may need to
        install a new mergemaster (cd src/usr.sbin/mergemaster && make
        install) after the buildworld before this step if you last updated
        from current before 20020224 or from -stable before 20020408.

        [8] In order to have a kernel that can run the 4.x binaries
        needed to do an installworld, you must include the COMPAT_FREEBSD4
        option in your kernel.  Failure to do so may leave you with a system
        that is hard to boot to recover. A similar kernel option COMPAT_FREEBSD5
        is required to run the 5.x binaries on more recent kernels.

        Make sure that you merge any new devices from GENERIC since the
        last time you updated your kernel config file.

        [9] When checking out sources, you must include the -P flag to have
        cvs prune empty directories.

        If CPUTYPE is defined in your /etc/make.conf, make sure to use the
        "?=" instead of the "=" assignment operator, so that buildworld can
        override the CPUTYPE if it needs to.

        MAKEOBJDIRPREFIX must be defined in an environment variable, and
        not on the command line, or in /etc/make.conf.  buildworld will
        warn if it is improperly defined.
FORMAT:

This file contains a list, in reverse chronological order, of major
breakages in tracking -current.  Not all things will be listed here,
and it only starts on October 16, 2004.  Updating files can found in
previous releases if your system is older than this.

Copyright information:

Copyright 1998-2005 M. Warner Losh.  All Rights Reserved.

Redistribution, publication, translation and use, with or without
modification, in full or in part, in any form or format of this
document are permitted without further permission from the author.

THIS DOCUMENT IS PROVIDED BY WARNER LOSH ``AS IS'' AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED.  IN NO EVENT SHALL WARNER LOSH BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

If you find this document useful, and you want to, you may buy the
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Contact Warner Losh if you have any questions about your use of
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$FreeBSD$