Add attribution for r258884.

[FreeBSD/FreeBSD.git] / UPDATING

Updating Information for FreeBSD current users

This file is maintained and copyrighted by M. Warner Losh <imp@freebsd.org>.
See end of file for further details.  For commonly done items, please see the
COMMON ITEMS: section later in the file.  These instructions assume that you
basically know what you are doing.  If not, then please consult the FreeBSD
handbook:

    http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html

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

NOTE: FreeBSD has switched from gcc to clang. If you have trouble bootstrapping
from older versions of FreeBSD, try WITHOUT_CLANG and WITH_GCC to bootstrap to
the tip of head, and then rebuild without this option. The bootstrap process from
older version of current across the gcc/clang cutover is a bit fragile.

NOTE TO PEOPLE WHO THINK THAT FreeBSD 11.x IS SLOW:
        FreeBSD 11.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.  (To completely disable malloc
        debugging, define MALLOC_PRODUCTION in /etc/make.conf, or to merely
        disable the most expensive debugging functionality run
        "ln -s 'abort:false,junk:false' /etc/malloc.conf".)

20140505:
        /etc/src.conf now affects only builds of the FreeBSD src tree. In the
        past, it affected all builds that used the bsd.*.mk files. The old
        behavior was a bug, but people may have relied upon it. To get this
        behavior back, you can .include /etc/src.conf from /etc/make.conf
        (which is still global and isn't changed). This also changes the
        behavior of incremental builds inside the tree of individual
        directories. Set MAKESYSPATH to ".../share/mk" to do that.
        Although this has survived make universe and some upgrade scenarios,
        other upgrade scenarios may have broken. At least one form of
        temporary breakage was fixed with MAKESYSPATH settings for buildworld
        as well...

        One side effect of all this cleaning up is that bsd.compiler.mk
        is no longer implicitly included by bsd.own.mk. If you wish to
        use COMPILER_TYPE, you must now explicitly include bsd.compiler.mk
        as well.

20140430:
        The lindev device has been removed since /dev/full has been made a
        standard device.  __FreeBSD_version has been bumped.

20140418:
        The YES_HESIOD knob has been removed. It has been obsolete for
        a decade. Please move to using WITH_HESIOD instead or your builds
        will silently lack HESIOD.

20140405:
        The uart(4) driver has been changed with respect to its handling
        of the low-level console. Previously the uart(4) driver prevented
        any process from changing the baudrate or the CLOCAL and HUPCL
        control flags. By removing the restrictions, operators can make
        changes to the serial console port without having to reboot.
        However, when getty(8) is started on the serial device that is
        associated with the low-level console, a misconfigured terminal
        line in /etc/ttys will now have a real impact.
        Before upgrading the kernel, make sure that /etc/ttys has the
        serial console device configured as 3wire without baudrate to
        preserve the previous behaviour. E.g:
            ttyu0  "/usr/libexec/getty 3wire"  vt100  on  secure

20140306:
        Support for libwrap (TCP wrappers) in rpcbind was disabled by default
        to improve performance.  To re-enable it, if needed, run rpcbind
        with command line option -W.

20140226:
        Switched back to the GPL dtc compiler due to updates in the upstream
        dts files not being supported by the BSDL dtc compiler. You will need
        to rebuild your kernel toolchain to pick up the new compiler. Core dumps
        may result while building dtb files during a kernel build if you fail
        to do so. Set WITHOUT_GPL_DTC if you require the BSDL compiler.

20140216:
        Clang and llvm have been upgraded to 3.4 release.

20140216:
        The nve(4) driver has been removed.  Please use the nfe(4) driver
        for NVIDIA nForce MCP Ethernet adapters instead.

20140212:
        An ABI incompatibility crept into the libc++ 3.4 import in r261283.
        This could cause certain C++ applications using shared libraries built
        against the previous version of libc++ to crash.  The incompatibility
        has now been fixed, but any C++ applications or shared libraries built
        between r261283 and r261801 should be recompiled.

20140204:
        OpenSSH will now ignore errors caused by kernel lacking of Capsicum
        capability mode support.  Please note that enabling the feature in
        kernel is still highly recommended.

20140131:
        OpenSSH is now built with sandbox support, and will use sandbox as
        the default privilege separation method.  This requires Capsicum
        capability mode support in kernel.

20140128:
        The libelf and libdwarf libraries have been updated to newer
        versions from upstream. Shared library version numbers for
        these two libraries were bumped. Any ports or binaries
        requiring these two libraries should be recompiled.
        __FreeBSD_version is bumped to 1100006.

20140110:
        If a Makefile in a tests/ directory was auto-generating a Kyuafile
        instead of providing an explicit one, this would prevent such
        Makefile from providing its own Kyuafile in the future during
        NO_CLEAN builds.  This has been fixed in the Makefiles but manual
        intervention is needed to clean an objdir if you use NO_CLEAN:
          # find /usr/obj -name Kyuafile | xargs rm -f

20131213:
        The behavior of gss_pseudo_random() for the krb5 mechanism
        has changed, for applications requesting a longer random string
        than produced by the underlying enctype's pseudo-random() function.
        In particular, the random string produced from a session key of
        enctype aes256-cts-hmac-sha1-96 or aes256-cts-hmac-sha1-96 will
        be different at the 17th octet and later, after this change.
        The counter used in the PRF+ construction is now encoded as a
        big-endian integer in accordance with RFC 4402.
        __FreeBSD_version is bumped to 1100004.

20131108:
        The WITHOUT_ATF build knob has been removed and its functionality
        has been subsumed into the more generic WITHOUT_TESTS.  If you were
        using the former to disable the build of the ATF libraries, you
        should change your settings to use the latter.

20131025:
        The default version of mtree is nmtree which is obtained from
        NetBSD.  The output is generally the same, but may vary
        slightly.  If you found you need identical output adding
        "-F freebsd9" to the command line should do the trick.  For the
        time being, the old mtree is available as fmtree.

20131014:
        libbsdyml has been renamed to libyaml and moved to /usr/lib/private.
        This will break ports-mgmt/pkg. Rebuild the port, or upgrade to pkg
        1.1.4_8 and verify bsdyml not linked in, before running "make
        delete-old-libs":
          # make -C /usr/ports/ports-mgmt/pkg build deinstall install clean
          or
          # pkg install pkg; ldd /usr/local/sbin/pkg | grep bsdyml

20131010:
        The rc.d/jail script has been updated to support jail(8)
        configuration file.  The "jail_<jname>_*" rc.conf(5) variables
        for per-jail configuration are automatically converted to
        /var/run/jail.<jname>.conf before the jail(8) utility is invoked.
        This is transparently backward compatible.  See below about some
        incompatibilities and rc.conf(5) manual page for more details.

        These variables are now deprecated in favor of jail(8) configuration
        file.  One can use "rc.d/jail config <jname>" command to generate
        a jail(8) configuration file in /var/run/jail.<jname>.conf without
        running the jail(8) utility.   The default pathname of the
        configuration file is /etc/jail.conf and can be specified by
        using $jail_conf or $jail_<jname>_conf variables.

        Please note that jail_devfs_ruleset accepts an integer at
        this moment.  Please consider to rewrite the ruleset name
        with an integer.

20130930:
        BIND has been removed from the base system.  If all you need
        is a local resolver, simply enable and start the local_unbound
        service instead.  Otherwise, several versions of BIND are
        available in the ports tree.   The dns/bind99 port is one example.

        With this change, nslookup(1) and dig(1) are no longer in the base
        system.  Users should instead use host(1) and drill(1) which are
        in the base system.  Alternatively, nslookup and dig can
        be obtained by installing the dns/bind-tools port.

20130916:
        With the addition of unbound(8), a new unbound user is now
        required during installworld.  "mergemaster -p" can be used to
        add the user prior to installworld, as documented in the handbook.

20130911:
        OpenSSH is now built with DNSSEC support, and will by default
        silently trust signed SSHFP records.  This can be controlled with
        the VerifyHostKeyDNS client configuration setting.  DNSSEC support
        can be disabled entirely with the WITHOUT_LDNS option in src.conf.

20130906:
        The GNU Compiler Collection and C++ standard library (libstdc++)
        are no longer built by default on platforms where clang is the system
        compiler.  You can enable them with the WITH_GCC and WITH_GNUCXX
        options in src.conf.  

20130905:
        The PROCDESC kernel option is now part of the GENERIC kernel
        configuration and is required for the rwhod(8) to work.
        If you are using custom kernel configuration, you should include
        'options PROCDESC'.

20130905:
        The API and ABI related to the Capsicum framework was modified
        in backward incompatible way. The userland libraries and programs
        have to be recompiled to work with the new kernel. This includes the
        following libraries and programs, but the whole buildworld is
        advised: libc, libprocstat, dhclient, tcpdump, hastd, hastctl,
        kdump, procstat, rwho, rwhod, uniq.

20130903:
        AES-NI intrinsic support has been added to gcc.  The AES-NI module
        has been updated to use this support.  A new gcc is required to build
        the aesni module on both i386 and amd64.

20130821:
        The PADLOCK_RNG and RDRAND_RNG kernel options are now devices.
        Thus "device padlock_rng" and "device rdrand_rng" should be
        used instead of "options PADLOCK_RNG" & "options RDRAND_RNG".

20130813:
        WITH_ICONV has been split into two feature sets.  WITH_ICONV now
        enables just the iconv* functionality and is now on by default.
        WITH_LIBICONV_COMPAT enables the libiconv api and link time
        compatability.  Set WITHOUT_ICONV to build the old way.
        If you have been using WITH_ICONV before, you will very likely
        need to turn on WITH_LIBICONV_COMPAT.

20130806:
        INVARIANTS option now enables DEBUG for code with OpenSolaris and
        Illumos origin, including ZFS.  If you have INVARIANTS in your
        kernel configuration, then there is no need to set DEBUG or ZFS_DEBUG
        explicitly.
        DEBUG used to enable witness(9) tracking of OpenSolaris (mostly ZFS)
        locks if WITNESS option was set.  Because that generated a lot of
        witness(9) reports and all of them were believed to be false
        positives, this is no longer done.  New option OPENSOLARIS_WITNESS
        can be used to achieve the previous behavior.

20130806:
        Timer values in IPv6 data structures now use time_uptime instead
        of time_second.  Although this is not a user-visible functional
        change, userland utilities which directly use them---ndp(8),
        rtadvd(8), and rtsold(8) in the base system---need to be updated
        to r253970 or later.

20130802:
        find -delete can now delete the pathnames given as arguments,
        instead of only files found below them or if the pathname did
        not contain any slashes. Formerly, the following error message
        would result:

        find: -delete: <path>: relative path potentially not safe

        Deleting the pathnames given as arguments can be prevented
        without error messages using -mindepth 1 or by changing
        directory and passing "." as argument to find. This works in the
        old as well as the new version of find.

20130726:
        Behavior of devfs rules path matching has been changed.
        Pattern is now always matched against fully qualified devfs
        path and slash characters must be explicitly matched by
        slashes in pattern (FNM_PATHNAME). Rulesets involving devfs
        subdirectories must be reviewed.

20130716:
        The default ARM ABI has changed to the ARM EABI. The old ABI is
        incompatible with the ARM EABI and all programs and modules will
        need to be rebuilt to work with a new kernel.

        To keep using the old ABI ensure the WITHOUT_ARM_EABI knob is set.

        NOTE: Support for the old ABI will be removed in the future and
        users are advised to upgrade.

20130709:
        pkg_install has been disconnected from the build if you really need it
        you should add WITH_PKGTOOLS in your src.conf(5).

20130709:
        Most of network statistics structures were changed to be able
        keep 64-bits counters. Thus all tools, that work with networking
        statistics, must be rebuilt (netstat(1), bsnmpd(1), etc.)

20130629:
        Fix targets that run multiple make's to use && rather than ;
        so that subsequent steps depend on success of previous.

        NOTE: if building 'universe' with -j* on stable/8 or stable/9
        it would be better to start the build using bmake, to avoid
        overloading the machine.

20130618:
        Fix a bug that allowed a tracing process (e.g. gdb) to write
        to a memory-mapped file in the traced process's address space
        even if neither the traced process nor the tracing process had
        write access to that file.

20130615:
        CVS has been removed from the base system.  An exact copy
        of the code is available from the devel/cvs port.

20130613:
        Some people report the following error after the switch to bmake:

                make: illegal option -- J
                usage: make [-BPSXeiknpqrstv] [-C directory] [-D variable]
                        ...
                *** [buildworld] Error code 2

        this likely due to an old instance of make in
        ${MAKEPATH} (${MAKEOBJDIRPREFIX}${.CURDIR}/make.${MACHINE})
        which src/Makefile will use that blindly, if it exists, so if
        you see the above error:

                rm -rf `make -V MAKEPATH`

        should resolve it.

20130516:
        Use bmake by default.
        Whereas before one could choose to build with bmake via
        -DWITH_BMAKE one must now use -DWITHOUT_BMAKE to use the old
        make. The goal is to remove these knobs for 10-RELEASE.

        It is worth noting that bmake (like gmake) treats the command
        line as the unit of failure, rather than statements within the
        command line.  Thus '(cd some/where && dosomething)' is safer
        than 'cd some/where; dosomething'. The '()' allows consistent
        behavior in parallel build.

20130429:
        Fix a bug that allows NFS clients to issue READDIR on files.

20130426:
        The WITHOUT_IDEA option has been removed because
        the IDEA patent expired.

20130426:
        The sysctl which controls TRIM support under ZFS has been renamed
        from vfs.zfs.trim_disable -> vfs.zfs.trim.enabled and has been
        enabled by default.

20130425:
        The mergemaster command now uses the default MAKEOBJDIRPREFIX
        rather than creating it's own in the temporary directory in
        order allow access to bootstrapped versions of tools such as
        install and mtree.  When upgrading from version of FreeBSD where
        the install command does not support -l, you will need to
        install a new mergemaster command if mergemaster -p is required.
        This can be accomplished with the command (cd src/usr.sbin/mergemaster
        && make install).

20130404:
        Legacy ATA stack, disabled and replaced by new CAM-based one since
        FreeBSD 9.0, completely removed from the sources.  Kernel modules
        atadisk and atapi*, user-level tools atacontrol and burncd are
        removed.  Kernel option `options ATA_CAM` is now permanently enabled
        and removed.

20130319:
        SOCK_CLOEXEC and SOCK_NONBLOCK flags have been added to socket(2)
        and socketpair(2). Software, in particular Kerberos, may
        automatically detect and use these during building. The resulting
        binaries will not work on older kernels.

20130308:
        CTL_DISABLE has also been added to the sparc64 GENERIC (for further
        information, see the respective 20130304 entry).

20130304:
        Recent commits to callout(9) changed the size of struct callout,
        so the KBI is probably heavily disturbed. Also, some functions
        in callout(9)/sleep(9)/sleepqueue(9)/condvar(9) KPIs were replaced
        by macros. Every kernel module using it won't load, so rebuild
        is requested.

        The ctl device has been re-enabled in GENERIC for i386 and amd64,
        but does not initialize by default (because of the new CTL_DISABLE
        option) to save memory.  To re-enable it, remove the CTL_DISABLE
        option from the kernel config file or set kern.cam.ctl.disable=0
        in /boot/loader.conf.

20130301:
        The ctl device has been disabled in GENERIC for i386 and amd64.
        This was done due to the extra memory being allocated at system
        initialisation time by the ctl driver which was only used if
        a CAM target device was created.  This makes a FreeBSD system
        unusable on 128MB or less of RAM.

20130208:
        A new compression method (lz4) has been merged to -HEAD.  Please
        refer to zpool-features(7) for more information.

        Please refer to the "ZFS notes" section of this file for information
        on upgrading boot ZFS pools.

20130129:
        A BSD-licensed patch(1) variant has been added and is installed
        as bsdpatch, being the GNU version the default patch.
        To inverse the logic and use the BSD-licensed one as default,
        while having the GNU version installed as gnupatch, rebuild
        and install world with the WITH_BSD_PATCH knob set.

20130121:
        Due to the use of the new -l option to install(1) during build
        and install, you must take care not to directly set the INSTALL
        make variable in your /etc/make.conf, /etc/src.conf, or on the
        command line.  If you wish to use the -C flag for all installs
        you may be able to add INSTALL+=-C to /etc/make.conf or
        /etc/src.conf.

20130118:
        The install(1) option -M has changed meaning and now takes an
        argument that is a file or path to append logs to.  In the
        unlikely event that -M was the last option on the command line
        and the command line contained at least two files and a target
        directory the first file will have logs appended to it.  The -M
        option served little practical purpose in the last decade so its
        use is expected to be extremely rare.

20121223:
        After switching to Clang as the default compiler some users of ZFS
        on i386 systems started to experience stack overflow kernel panics.
        Please consider using 'options KSTACK_PAGES=4' in such configurations.

20121222:
        GEOM_LABEL now mangles label names read from file system metadata.
        Mangling affect labels containing spaces, non-printable characters,
        '%' or '"'. Device names in /etc/fstab and other places may need to
        be updated.

20121217:
        By default, only the 10 most recent kernel dumps will be saved.  To
        restore the previous behaviour (no limit on the number of kernel dumps
        stored in the dump directory) add the following line to /etc/rc.conf:

                savecore_flags=""

20121201:
        With the addition of auditdistd(8), a new auditdistd user is now
        required during installworld.  "mergemaster -p" can be used to
        add the user prior to installworld, as documented in the handbook.

20121117:
        The sin6_scope_id member variable in struct sockaddr_in6 is now
        filled by the kernel before passing the structure to the userland via
        sysctl or routing socket.  This means the KAME-specific embedded scope
        id in sin6_addr.s6_addr[2] is always cleared in userland application.
        This behavior can be controlled by net.inet6.ip6.deembed_scopeid.
        __FreeBSD_version is bumped to 1000025.

20121105:
        On i386 and amd64 systems WITH_CLANG_IS_CC is now the default.
        This means that the world and kernel will be compiled with clang
        and that clang will be installed as /usr/bin/cc, /usr/bin/c++,
        and /usr/bin/cpp.  To disable this behavior and revert to building
        with gcc, compile with WITHOUT_CLANG_IS_CC. Really old versions
        of current may need to bootstrap WITHOUT_CLANG first if the clang
        build fails (its compatibility window doesn't extend to the 9 stable
        branch point).

20121102:
        The IPFIREWALL_FORWARD kernel option has been removed. Its
        functionality now turned on by default.

20121023:
        The ZERO_COPY_SOCKET kernel option has been removed and
        split into SOCKET_SEND_COW and SOCKET_RECV_PFLIP.
        NB: SOCKET_SEND_COW uses the VM page based copy-on-write
        mechanism which is not safe and may result in kernel crashes.
        NB: The SOCKET_RECV_PFLIP mechanism is useless as no current
        driver supports disposeable external page sized mbuf storage.
        Proper replacements for both zero-copy mechanisms are under
        consideration and will eventually lead to complete removal
        of the two kernel options.

20121023:
        The IPv4 network stack has been converted to network byte
        order. The following modules need to be recompiled together
        with kernel: carp(4), divert(4), gif(4), siftr(4), gre(4),
        pf(4), ipfw(4), ng_ipfw(4), stf(4).

20121022:
        Support for non-MPSAFE filesystems was removed from VFS. The
        VFS_VERSION was bumped, all filesystem modules shall be
        recompiled.

20121018:
        All the non-MPSAFE filesystems have been disconnected from
        the build. The full list includes: codafs, hpfs, ntfs, nwfs,
        portalfs, smbfs, xfs.

20121016:
        The interface cloning API and ABI has changed. The following
        modules need to be recompiled together with kernel:
        ipfw(4), pfsync(4), pflog(4), usb(4), wlan(4), stf(4),
        vlan(4), disc(4), edsc(4), if_bridge(4), gif(4), tap(4),
        faith(4), epair(4), enc(4), tun(4), if_lagg(4), gre(4).

20121015:
        The sdhci driver was split in two parts: sdhci (generic SD Host
        Controller logic) and sdhci_pci (actual hardware driver).
        No kernel config modifications are required, but if you
        load sdhc as a module you must switch to sdhci_pci instead.

20121014:
        Import the FUSE kernel and userland support into base system.

20121013:
        The GNU sort(1) program has been removed since the BSD-licensed
        sort(1) has been the default for quite some time and no serious
        problems have been reported.  The corresponding WITH_GNU_SORT
        knob has also gone.

20121006:
        The pfil(9) API/ABI for AF_INET family has been changed. Packet
        filtering modules: pf(4), ipfw(4), ipfilter(4) need to be recompiled
        with new kernel.

20121001:
        The net80211(4) ABI has been changed to allow for improved driver
        PS-POLL and power-save support.  All wireless drivers need to be
        recompiled to work with the new kernel.

20120913:
        The random(4) support for the VIA hardware random number
        generator (`PADLOCK') is no longer enabled unconditionally.
        Add the padlock_rng device in the custom kernel config if
        needed.  The GENERIC kernels on i386 and amd64 do include the
        device, so the change only affects the custom kernel
        configurations.

20120908:
        The pf(4) packet filter ABI has been changed. pfctl(8) and
        snmp_pf module need to be recompiled to work with new kernel.

20120828:
        A new ZFS feature flag "com.delphix:empty_bpobj" has been merged
        to -HEAD. Pools that have empty_bpobj in active state can not be
        imported read-write with ZFS implementations that do not support
        this feature. For more information read the zpool-features(5)
        manual page.

20120727:
        The sparc64 ZFS loader has been changed to no longer try to auto-
        detect ZFS providers based on diskN aliases but now requires these
        to be explicitly listed in the OFW boot-device environment variable. 

20120712:
        The OpenSSL has been upgraded to 1.0.1c.  Any binaries requiring
        libcrypto.so.6 or libssl.so.6 must be recompiled.  Also, there are
        configuration changes.  Make sure to merge /etc/ssl/openssl.cnf.

20120712:
        The following sysctls and tunables have been renamed for consistency
        with other variables:
          kern.cam.da.da_send_ordered   -> kern.cam.da.send_ordered
          kern.cam.ada.ada_send_ordered -> kern.cam.ada.send_ordered

20120628:
        The sort utility has been replaced with BSD sort.  For now, GNU sort
        is also available as "gnusort" or the default can be set back to
        GNU sort by setting WITH_GNU_SORT.  In this case, BSD sort will be
        installed as "bsdsort".

20120611:
        A new version of ZFS (pool version 5000) has been merged to -HEAD.
        Starting with this version the old system of ZFS pool versioning
        is superseded by "feature flags". This concept enables forward
        compatibility against certain future changes in functionality of ZFS
        pools. The first read-only compatible "feature flag" for ZFS pools
        is named "com.delphix:async_destroy". For more information
        read the new zpool-features(5) manual page.
        Please refer to the "ZFS notes" section of this file for information
        on upgrading boot ZFS pools.

20120417:
        The malloc(3) implementation embedded in libc now uses sources imported
        as contrib/jemalloc.  The most disruptive API change is to
        /etc/malloc.conf.  If your system has an old-style /etc/malloc.conf,
        delete it prior to installworld, and optionally re-create it using the
        new format after rebooting.  See malloc.conf(5) for details
        (specifically the TUNING section and the "opt.*" entries in the MALLCTL
        NAMESPACE section).

20120328:
        Big-endian MIPS TARGET_ARCH values no longer end in "eb".  mips64eb
        is now spelled mips64.  mipsn32eb is now spelled mipsn32.  mipseb is
        now spelled mips.  This is to aid compatibility with third-party
        software that expects this naming scheme in uname(3).  Little-endian
        settings are unchanged. If you are updating a big-endian mips64 machine
        from before this change, you may need to set MACHINE_ARCH=mips64 in
        your environment before the new build system will recognize your machine.

20120306:
        Disable by default the option VFS_ALLOW_NONMPSAFE for all supported
        platforms.

20120229:
        Now unix domain sockets behave "as expected" on nullfs(5). Previously
        nullfs(5) did not pass through all behaviours to the underlying layer,
        as a result if we bound to a socket on the lower layer we could connect
        only to the lower path; if we bound to the upper layer we could connect
        only to the upper path. The new behavior is one can connect to both the
        lower and the upper paths regardless what layer path one binds to.

20120211:
        The getifaddrs upgrade path broken with 20111215 has been restored.
        If you have upgraded in between 20111215 and 20120209 you need to
        recompile libc again with your kernel.  You still need to recompile
        world to be able to configure CARP but this restriction already
        comes from 20111215.

20120114:
        The set_rcvar() function has been removed from /etc/rc.subr.  All
        base and ports rc.d scripts have been updated, so if you have a
        port installed with a script in /usr/local/etc/rc.d you can either
        hand-edit the rcvar= line, or reinstall the port.

        An easy way to handle the mass-update of /etc/rc.d:
        rm /etc/rc.d/* && mergemaster -i

20120109:
        panic(9) now stops other CPUs in the SMP systems, disables interrupts
        on the current CPU and prevents other threads from running.
        This behavior can be reverted using the kern.stop_scheduler_on_panic
        tunable/sysctl.
        The new behavior can be incompatible with kern.sync_on_panic.

20111215:
        The carp(4) facility has been changed significantly. Configuration
        of the CARP protocol via ifconfig(8) has changed, as well as format
        of CARP events submitted to devd(8) has changed. See manual pages
        for more information. The arpbalance feature of carp(4) is currently
        not supported anymore.

        Size of struct in_aliasreq, struct in6_aliasreq has changed. User
        utilities using SIOCAIFADDR, SIOCAIFADDR_IN6, e.g. ifconfig(8),
        need to be recompiled.

20111122:
        The acpi_wmi(4) status device /dev/wmistat has been renamed to
        /dev/wmistat0.

20111108:
        The option VFS_ALLOW_NONMPSAFE option has been added in order to
        explicitely support non-MPSAFE filesystems.
        It is on by default for all supported platform at this present
        time.

20111101:
        The broken amd(4) driver has been replaced with esp(4) in the amd64,
        i386 and pc98 GENERIC kernel configuration files.

20110930:
        sysinstall has been removed

20110923:
        The stable/9 branch created in subversion.  This corresponds to the
        RELENG_9 branch in CVS.

COMMON ITEMS:

        General Notes
        -------------
        Avoid using make -j when upgrading.  While generally safe, there are
        sometimes problems using -j to upgrade.  If your upgrade fails with
        -j, please try again without -j.  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.

        When upgrading a live system, having a root shell around before
        installing anything can help undo problems. Not having a root shell
        around can lead to problems if pam has changed too much from your
        starting point to allow continued authentication after the upgrade.

        ZFS notes
        ---------
        When upgrading the boot ZFS pool to a new version, always follow
        these two steps:

        1.) recompile and reinstall the ZFS boot loader and boot block
        (this is part of "make buildworld" and "make installworld")

        2.) update the ZFS boot block on your boot drive

        The following example updates the ZFS boot block on the first
        partition (freebsd-boot) of a GPT partitioned drive ad0:
        "gpart bootcode -p /boot/gptzfsboot -i 1 ad0"

        Non-boot pools do not need these updates.

        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 CURRENT system.  Replace
        ${arch} with the architecture of your machine (e.g. "i386",
        "arm", "amd64", "ia64", "pc98", "sparc64", "powerpc", "mips", 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 -Fp                                 [5]
        make installworld
        mergemaster -Fi                                 [4]
        make delete-old                                 [6]
        <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} -DDB_FROM_SRC
        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 ports/misc/compat*>
        <reboot>


        To upgrade in-place from 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 -Fp                                 [5]
        make installworld
        mergemaster -Fi                                 [4]
        make delete-old                                 [6]
        <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.  The -U option is also useful to consider.
        See mergemaster(8) for more information.

        [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 20130425 or from -stable before 20130430.

        [6] This only deletes old files and directories. Old libraries
        can be deleted by "make delete-old-libs", but you have to make
        sure that no program is using those libraries anymore.

        [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.  And so on
        for COMPAT_FREEBSD6 and COMPAT_FREEBSD7.

        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.  It is not guaranteed to be a complete
list of such breakages, and only contains entries since October 10, 2007.
If you need to see UPDATING entries from before that date, you will need
to fetch an UPDATING file from an older FreeBSD release.

Copyright information:

Copyright 1998-2009 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
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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
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Contact Warner Losh if you have any questions about your use of
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$FreeBSD$