xref: /freebsd/UPDATING (revision e04518a677826c6fbeca0bf767f79b47dd94d671)

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:

    https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/current-stable.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 12.x IS SLOW:
	FreeBSD 12.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".)


****************************** SPECIAL WARNING: ******************************

	Due to a bug in some versions of clang that's very hard to workaround in
	the upgrade process, to upgrade to -current you must first upgrade
	either stable/9 after r286035 or stable/10 after r286033 (including
	10.3-RELEASE) or current after r286007 (including stable/11 and
	11.0-RELEASE). These revisions post-date the 10.2 and 9.3 releases, so
	you'll need to take the unusual step of upgrading to the tip of the
	stable branch before moving to 11 or -current via a source upgrade.
	stable/11 and 11.0-RELEASE have working newer compiler. This differs
	from the historical situation where one could upgrade from anywhere on
	the last couple of stable branches, so be careful.

	If you're running a hybrid system on 9.x or 10.x with an updated clang
	compiler or are using an supported external toolchain, the build system
	will allow the upgrade. Otherwise it will print a reminder.

****************************** SPECIAL WARNING: ******************************

20180114:
	Clang, llvm, lld, lldb, compiler-rt and libc++ have been upgraded to
	6.0.0.  Please see the 20141231 entry below for information about
	prerequisites and upgrading, if you are not already using clang 3.5.0
	or higher.

20180110:
	LLVM's lld linker is now used as the FreeBSD/amd64 bootstrap linker.
	This means it is used to link the kernel and userland libraries and
	executables, but is not yet installed as /usr/bin/ld by default.

	To revert to ld.bfd as the bootstrap linker, in /etc/src.conf set
        WITHOUT_LLD_BOOTSTRAP=yes

20180110:
	On i386, pmtimer has been removed. Its functionality has been folded
	into apm. It was a no-op on ACPI in current for a while now (but was still
	needed on i386 in FreeBSD 11 and earlier). Users may need to remove it
	from kernel config files.

20180104:
	The use of RSS hash from the network card aka flowid has been
	disabled by default for lagg(4) as it's currently incompatible with
	the lacp and loadbalance protocols.

	This can be re-enabled by setting the following in loader.conf:
	net.link.lagg.default_use_flowid="1"

20180102:
	The SW_WATCHDOG option is no longer necessary to enable the
	hardclock-based software watchdog if no hardware watchdog is
	configured. As before, SW_WATCHDOG will cause the software
	watchdog to be enabled even if a hardware watchdog is configured.

20171215:
	r326887 fixes the issue described in the 20171214 UPDATING entry.
	r326888 flips the switch back to building GELI support always.

20171214:
	r362593 broke ZFS + GELI support for reasons unknown. However,
	it also broke ZFS support generally, so GELI has been turned off
	by default as the lesser evil in r326857. If you boot off ZFS and/or
	GELI, it might not be a good time to update.

20171125:
	PowerPC users must update loader(8) by rebuilding world before
	installing a new kernel, as the protocol connecting them has
	changed. Without the update, loader metadata will not be passed
	successfully to the kernel and users will have to enter their
	root partition at the kernel mountroot prompt to continue booting.
	Newer versions of loader can boot old kernels without issue.

20171110:
	The LOADER_FIREWIRE_SUPPORT build variable as been renamed to
	WITH/OUT_LOADER_FIREWIRE. LOADER_{NO_,}GELI_SUPPORT has been renamed
	to WITH/OUT_LOADER_GELI.

20171106:
	The naive and non-compliant support of posix_fallocate(2) in ZFS
	has been removed as of r325320.  The system call now returns EINVAL
	when used on a ZFS file.  Although the new behavior complies with the
	standard, some consumers are not prepared to cope with it.
	One known victim is lld prior to r325420.

20171102:
	Building in a FreeBSD src checkout will automatically create object
	directories now rather than store files in the current directory if
	'make obj' was not ran.  Calling 'make obj' is no longer necessary.
	This feature can be disabled by setting WITHOUT_AUTO_OBJ=yes in
	/etc/src-env.conf (not /etc/src.conf), or passing the option in the
	environment.

20171101:
	The default MAKEOBJDIR has changed from /usr/obj/<srcdir> for native
	builds, and /usr/obj/<arch>/<srcdir> for cross-builds, to a unified
	/usr/obj/<srcdir>/<arch>.  This behavior can be changed to the old
	format by setting WITHOUT_UNIFIED_OBJDIR=yes in /etc/src-env.conf,
	the environment, or with -DWITHOUT_UNIFIED_OBJDIR when building.
	The UNIFIED_OBJDIR option is a transitional feature that will be
	removed for 12.0 release; please migrate to the new format for any
	tools by looking up the OBJDIR used by 'make -V .OBJDIR' means rather
	than hardcoding paths.

20171028:
	The native-xtools target no longer installs the files by default to the
	OBJDIR.  Use the native-xtools-install target with a DESTDIR to install
	to ${DESTDIR}/${NXTP} where NXTP defaults to /nxb-bin.

20171021:
	As part of the boot loader infrastructure cleanup, LOADER_*_SUPPORT
	options are changing from controlling the build if defined / undefined
	to controlling the build with explicit 'yes' or 'no' values. They will
	shift to WITH/WITHOUT options to match other options in the system.

20171010:
	libstand has turned into a private library for sys/boot use only.
	It is no longer supported as a public interface outside of sys/boot.

20171005:
	The arm port has split armv6 into armv6 and armv7. armv7 is now
	a valid TARGET_ARCH/MACHINE_ARCH setting. If you have an armv7 system
	and are running a kernel from before r324363, you will need to add
	MACHINE_ARCH=armv7 to 'make buildworld' to do a native build.

20171003:
	When building multiple kernels using KERNCONF, non-existent KERNCONF
	files will produce an error and buildkernel will fail. Previously
	missing KERNCONF files silently failed giving no indication as to
	why, only to subsequently discover during installkernel that the
	desired kernel was never built in the first place.

20170912:
	The default serial number format for CTL LUNs has changed.  This will
	affect users who use /dev/diskid/* device nodes, or whose FibreChannel
	or iSCSI clients care about their LUNs' serial numbers.  Users who
	require serial number stability should hardcode serial numbers in
	/etc/ctl.conf .

20170912:
	For 32-bit arm compiled for hard-float support, soft-floating point
	binaries now always get their shared libraries from
	LD_SOFT_LIBRARY_PATH (in the past, this was only used if
	/usr/libsoft also existed). Only users with a hard-float ld.so, but
	soft-float everything else should be affected.

20170826:
	The geli password typed at boot is now hidden.  To restore the previous
	behavior, see geli(8) for configuration options.

20170825:
	Move PMTUD blackhole counters to TCPSTATS and remove them from bare
	sysctl values.  Minor nit, but requires a rebuild of both world/kernel
	to complete.

20170814:
	"make check" behavior (made in ^/head@r295380) has been changed to
	execute from a limited sandbox, as opposed to executing from
	${TESTSDIR}.

	Behavioral changes:
	- The "beforecheck" and "aftercheck" targets are now specified.
	- ${CHECKDIR} (added in commit noted above) has been removed.
	- Legacy behavior can be enabled by setting
	  WITHOUT_MAKE_CHECK_USE_SANDBOX in src.conf(5) or the environment.

	If the limited sandbox mode is enabled, "make check" will execute
	"make distribution", then install, execute the tests, and clean up the
	sandbox if successful.

	The "make distribution" and "make install" targets are typically run as
	root to set appropriate permissions and ownership at installation time.
	The end-user should set "WITH_INSTALL_AS_USER" in src.conf(5) or the
	environment if executing "make check" with limited sandbox mode using
	an unprivileged user.

20170808:
	Since the switch to GPT disk labels, fsck for UFS/FFS has been
	unable to automatically find alternate superblocks. As of r322297,
	the information needed to find alternate superblocks has been
	moved to the end of the area reserved for the boot block.
	Filesystems created with a newfs of this vintage or later
	will create the recovery information. If you have a filesystem
	created prior to this change and wish to have a recovery block
	created for your filesystem, you can do so by running fsck in
	foreground mode (i.e., do not use the -p or -y options). As it
	starts, fsck will ask ``SAVE DATA TO FIND ALTERNATE SUPERBLOCKS''
	to which you should answer yes.

20170728:
	As of r321665, an NFSv4 server configuration that services
	Kerberos mounts or clients that do not support the uid/gid in
	owner/owner_group string capability, must explicitly enable
	the nfsuserd daemon by adding nfsuserd_enable="YES" to the
	machine's /etc/rc.conf file.

20170722:
	Clang, llvm, lldb, compiler-rt and libc++ have been upgraded to 5.0.0.
	Please see the 20141231 entry below for information about prerequisites
	and upgrading, if you are not already using clang 3.5.0 or higher.

20170701:
	WITHOUT_RCMDS is now the default. Set WITH_RCMDS if you need the
	r-commands (rlogin, rsh, etc.) to be built with the base system.

20170625:
	The FreeBSD/powerpc platform now uses a 64-bit type for time_t.  This is
	a very major ABI incompatible change, so users of FreeBSD/powerpc must
	be careful when performing source upgrades.  It is best to run
	'make installworld' from an alternate root system, either a live
	CD/memory stick, or a temporary root partition.  Additionally, all ports
	must be recompiled.  powerpc64 is largely unaffected, except in the case
	of 32-bit compatibility.  All 32-bit binaries will be affected.

20170623:
	Forward compatibility for the "ino64" project have been committed. This
	will allow most new binaries to run on older kernels in a limited
	fashion.  This prevents many of the common foot-shooting actions in the
	upgrade as well as the limited ability to roll back the kernel across
	the ino64 upgrade. Complicated use cases may not work properly, though
	enough simpler ones work to allow recovery in most situations.

20170620:
	Switch back to the BSDL dtc (Device Tree Compiler). Set WITH_GPL_DTC
	if you require the GPL compiler.

20170618:
	The internal ABI used for communication between the NFS kernel modules
	was changed by r320085, so __FreeBSD_version was bumped to
	ensure all the NFS related modules are updated together.

20170617:
	The ABI of struct event was changed by extending the data
	member to 64bit and adding ext fields.  For upgrade, same
	precautions as for the entry 20170523 "ino64" must be
	followed.

20170531:
	The GNU roff toolchain has been removed from base. To render manpages
	which are not supported by mandoc(1), man(1) can fallback on GNU roff
	from ports (and recommends to install it).
	To render roff(7) documents, consider using GNU roff from ports or the
	heirloom doctools roff toolchain from ports via pkg install groff or
	via pkg install heirloom-doctools.

20170524:
	The ath(4) and ath_hal(4) modules now build piecemeal to allow for
	smaller runtime footprint builds.  This is useful for embedded systems
	which only require one chipset support.

	If you load it as a module, make sure this is in /boot/loader.conf:

	if_ath_load="YES"

	This will load the HAL, all chip/RF backends and if_ath_pci.
	If you have if_ath_pci in /boot/loader.conf, ensure it is after
	if_ath or it will not load any HAL chipset support.

	If you want to selectively load things (eg on ye cheape ARM/MIPS
	platforms where RAM is at a premium) you should:

	* load ath_hal
	* load the chip modules in question
	* load ath_rate, ath_dfs
	* load ath_main
	* load if_ath_pci and/or if_ath_ahb depending upon your particular
	  bus bind type - this is where probe/attach is done.

	For further comments/feedback, poke adrian@ .

20170523:
	The "ino64" 64-bit inode project has been committed, which extends
	a number of types to 64 bits.  Upgrading in place requires care and
	adherence to the documented upgrade procedure.

	If using a custom kernel configuration ensure that the
	COMPAT_FREEBSD11 option is included (as during the upgrade the
	system will be running the ino64 kernel with the existing world).

	For the safest in-place upgrade begin by removing previous build
	artifacts via "rm -rf /usr/obj/*".   Then, carefully follow the
	full procedure documented below under the heading "To rebuild
	everything and install it on the current system."  Specifically,
	a reboot is required after installing the new kernel before
	installing world.

20170424:
	The NATM framework including the en(4), fatm(4), hatm(4), and
	patm(4) devices has been removed.  Consumers should plan a
	migration before the end-of-life date for FreeBSD 11.

20170420:
	GNU diff has been replaced by a BSD licensed diff. Some features of GNU
	diff has not been implemented, if those are needed a newer version of
	GNU diff is available via the diffutils package under the gdiff name.

20170413:
	As of r316810 for ipfilter, keep frags is no longer assumed when
	keep state is specified in a rule. r316810 aligns ipfilter with
	documentation in man pages separating keep frags from keep state.
	This allows keep state to be specified without forcing keep frags
	and allows keep frags to be specified independently of keep state.
	To maintain previous behaviour, also specify keep frags with
	keep state (as documented in ipf.conf.5).

20170407:
	arm64 builds now use the base system LLD 4.0.0 linker by default,
	instead of requiring that the aarch64-binutils port or package be
	installed. To continue using aarch64-binutils, set
	CROSS_BINUTILS_PREFIX=/usr/local/aarch64-freebsd/bin .

20170405:
	The UDP optimization in entry 20160818 that added the sysctl
	net.inet.udp.require_l2_bcast has been reverted.  L2 broadcast
	packets will no longer be treated as L3 broadcast packets.

20170331:
	Binds and sends to the loopback addresses, IPv6 and IPv4, will now
	use any explicitly assigned loopback address available in the jail
	instead of using the first assigned address of the jail.

20170329:
	The ctl.ko module no longer implements the iSCSI target frontend:
	cfiscsi.ko does instead.

	If building cfiscsi.ko as a kernel module, the module can be loaded
	via one of the following methods:
	- `cfiscsi_load="YES"` in loader.conf(5).
	- Add `cfiscsi` to `$kld_list` in rc.conf(5).
	- ctladm(8)/ctld(8), when compiled with iSCSI support
	  (`WITH_ISCSI=yes` in src.conf(5))

	Please see cfiscsi(4) for more details.

20170316:
	The mmcsd.ko module now additionally depends on geom_flashmap.ko.
	Also, mmc.ko and mmcsd.ko need to be a matching pair built from the
	same source (previously, the dependency of mmcsd.ko on mmc.ko was
	missing, but mmcsd.ko now will refuse to load if it is incompatible
	with mmc.ko).

20170315:
	The syntax of ipfw(8) named states was changed to avoid ambiguity.
	If you have used named states in the firewall rules, you need to modify
	them after installworld and before rebooting. Now named states must
	be prefixed with colon.

20170311:
	The old drm (sys/dev/drm/) drivers for i915 and radeon have been
	removed as the userland we provide cannot use them. The KMS version
	(sys/dev/drm2) supports the same hardware.

20170302:
	Clang, llvm, lldb, compiler-rt and libc++ have been upgraded to 4.0.0.
	Please see the 20141231 entry below for information about prerequisites
	and upgrading, if you are not already using clang 3.5.0 or higher.

20170221:
	The code that provides support for ZFS .zfs/ directory functionality
	has been reimplemented.  It's not possible now to create a snapshot
	by mkdir under .zfs/snapshot/.  That should be the only user visible
	change.

20170216:
	EISA bus support has been removed. The WITH_EISA option is no longer
	valid.

20170215:
	MCA bus support has been removed.

20170127:
	The WITH_LLD_AS_LD / WITHOUT_LLD_AS_LD build knobs have been renamed
	WITH_LLD_IS_LD / WITHOUT_LLD_IS_LD, for consistency with CLANG_IS_CC.

20170112:
	The EM_MULTIQUEUE kernel configuration option is deprecated now that
	the em(4) driver conforms to iflib specifications.

20170109:
	The igb(4), em(4) and lem(4) ethernet drivers are now implemented via
	IFLIB.  If you have a custom kernel configuration that excludes em(4)
	but you use igb(4), you need to re-add em(4) to your custom configuration.

20161217:
	Clang, llvm, lldb, compiler-rt and libc++ have been upgraded to 3.9.1.
	Please see the 20141231 entry below for information about prerequisites
	and upgrading, if you are not already using clang 3.5.0 or higher.

20161124:
	Clang, llvm, lldb, compiler-rt and libc++ have been upgraded to 3.9.0.
	Please see the 20141231 entry below for information about prerequisites
	and upgrading, if you are not already using clang 3.5.0 or higher.

20161119:
	The layout of the pmap structure has changed for powerpc to put the pmap
	statistics at the front for all CPU variations.  libkvm(3) and all tools
	that link against it need to be recompiled.

20161030:
	isl(4) and cyapa(4) drivers now require a new driver,
	chromebook_platform(4), to work properly on Chromebook-class hardware.
	On other types of hardware the drivers may need to be configured using
	device hints.  Please see the corresponding manual pages for details.

20161017:
	The urtwn(4) driver was merged into rtwn(4) and now consists of
	rtwn(4) main module + rtwn_usb(4) and rtwn_pci(4) bus-specific
	parts.
	Also, firmware for RTL8188CE was renamed due to possible name
	conflict (rtwnrtl8192cU(B) -> rtwnrtl8192cE(B))

20161015:
	GNU rcs has been removed from base.  It is available as packages:
	- rcs: Latest GPLv3 GNU rcs version.
	- rcs57: Copy of the latest version of GNU rcs (GPLv2) before it was
	removed from base.

20161008:
	Use of the cc_cdg, cc_chd, cc_hd, or cc_vegas congestion control
	modules now requires that the kernel configuration contain the
	TCP_HHOOK option. (This option is included in the GENERIC kernel.)

20161003:
	The WITHOUT_ELFCOPY_AS_OBJCOPY src.conf(5) knob has been retired.
	ELF Tool Chain's elfcopy is always installed as /usr/bin/objcopy.

20160924:
	Relocatable object files with the extension of .So have been renamed
	to use an extension of .pico instead.  The purpose of this change is
	to avoid a name clash with shared libraries on case-insensitive file
	systems.  On those file systems, foo.So is the same file as foo.so.

20160918:
	GNU rcs has been turned off by default.  It can (temporarily) be built
	again by adding WITH_RCS knob in src.conf.
	Otherwise, GNU rcs is available from packages:
	- rcs: Latest GPLv3 GNU rcs version.
	- rcs57: Copy of the latest version of GNU rcs (GPLv2) from base.

20160918:
	The backup_uses_rcs functionality has been removed from rc.subr.

20160908:
	The queue(3) debugging macro, QUEUE_MACRO_DEBUG, has been split into
	two separate components, QUEUE_MACRO_DEBUG_TRACE and
	QUEUE_MACRO_DEBUG_TRASH.  Define both for the original
	QUEUE_MACRO_DEBUG behavior.

20160824:
	r304787 changed some ioctl interfaces between the iSCSI userspace
	programs and the kernel.  ctladm, ctld, iscsictl, and iscsid must be
	rebuilt to work with new kernels.  __FreeBSD_version has been bumped
	to 1200005.

20160818:
	The UDP receive code has been updated to only treat incoming UDP
	packets that were addressed to an L2 broadcast address as L3
	broadcast packets.  It is not expected that this will affect any
	standards-conforming UDP application.  The new behaviour can be
	disabled by setting the sysctl net.inet.udp.require_l2_bcast to
	0.

20160818:
	Remove the openbsd_poll system call.
	__FreeBSD_version has been bumped because of this.

20160622:
	The libc stub for the pipe(2) system call has been replaced with
	a wrapper that calls the pipe2(2) system call and the pipe(2)
	system call is now only implemented by the kernels that include
	"options COMPAT_FREEBSD10" in their config file (this is the
	default).  Users should ensure that this option is enabled in
	their kernel or upgrade userspace to r302092 before upgrading their
	kernel.

20160527:
	CAM will now strip leading spaces from SCSI disks' serial numbers.
	This will affect users who create UFS filesystems on SCSI disks using
	those disk's diskid device nodes.  For example, if /etc/fstab
	previously contained a line like
	"/dev/diskid/DISK-%20%20%20%20%20%20%20ABCDEFG0123456", you should
	change it to "/dev/diskid/DISK-ABCDEFG0123456".  Users of geom
	transforms like gmirror may also be affected.  ZFS users should
	generally be fine.

20160523:
	The bitstring(3) API has been updated with new functionality and
	improved performance.  But it is binary-incompatible with the old API.
	Objects built with the new headers may not be linked against objects
	built with the old headers.

20160520:
	The brk and sbrk functions have been removed from libc on arm64.
	Binutils from ports has been updated to not link to these
	functions and should be updated to the latest version before
	installing a new libc.

20160517:
	The armv6 port now defaults to hard float ABI. Limited support
	for running both hardfloat and soft float on the same system
	is available using the libraries installed with -DWITH_LIBSOFT.
	This has only been tested as an upgrade path for installworld
	and packages may fail or need manual intervention to run. New
	packages will be needed.

	To update an existing self-hosted armv6hf system, you must add
	TARGET_ARCH=armv6 on the make command line for both the build
	and the install steps.

20160510:
	Kernel modules compiled outside of a kernel build now default to
	installing to /boot/modules instead of /boot/kernel.  Many kernel
	modules built this way (such as those in ports) already overrode
	KMODDIR explicitly to install into /boot/modules.  However,
	manually building and installing a module from /sys/modules will
	now install to /boot/modules instead of /boot/kernel.

20160414:
	The CAM I/O scheduler has been committed to the kernel. There should be
	no user visible impact. This does enable NCQ Trim on ada SSDs. While the
	list of known rogues that claim support for this but actually corrupt
	data is believed to be complete, be on the lookout for data
	corruption. The known rogue list is believed to be complete:

		o Crucial MX100, M550 drives with MU01 firmware.
		o Micron M510 and M550 drives with MU01 firmware.
		o Micron M500 prior to MU07 firmware
		o Samsung 830, 840, and 850 all firmwares
		o FCCT M500 all firmwares

	Crucial has firmware http://www.crucial.com/usa/en/support-ssd-firmware
	with working NCQ TRIM. For Micron branded drives, see your sales rep for
	updated firmware. Black listed drives will work correctly because these
	drives work correctly so long as no NCQ TRIMs are sent to them. Given
	this list is the same as found in Linux, it's believed there are no
	other rogues in the market place. All other models from the above
	vendors work.

	To be safe, if you are at all concerned, you can quirk each of your
	drives to prevent NCQ from being sent by setting:
		kern.cam.ada.X.quirks="0x2"
	in loader.conf. If the drive requires the 4k sector quirk, set the
	quirks entry to 0x3.

20160330:
	The FAST_DEPEND build option has been removed and its functionality is
	now the one true way.  The old mkdep(1) style of 'make depend' has
	been removed.  See 20160311 for further details.

20160317:
	Resource range types have grown from unsigned long to uintmax_t.  All
	drivers, and anything using libdevinfo, need to be recompiled.

20160311:
	WITH_FAST_DEPEND is now enabled by default for in-tree and out-of-tree
	builds.  It no longer runs mkdep(1) during 'make depend', and the
	'make depend' stage can safely be skipped now as it is auto ran
	when building 'make all' and will generate all SRCS and DPSRCS before
	building anything else.  Dependencies are gathered at compile time with
	-MF flags kept in separate .depend files per object file.  Users should
	run 'make cleandepend' once if using -DNO_CLEAN to clean out older
	stale .depend files.

20160306:
	On amd64, clang 3.8.0 can now insert sections of type AMD64_UNWIND into
	kernel modules.  Therefore, if you load any kernel modules at boot time,
	please install the boot loaders after you install the kernel, but before
	rebooting, e.g.:

	make buildworld
	make kernel KERNCONF=YOUR_KERNEL_HERE
	make -C sys/boot install
	<reboot in single user>

	Then follow the usual steps, described in the General Notes section,
	below.

20160305:
	Clang, llvm, lldb and compiler-rt have been upgraded to 3.8.0.  Please
	see the 20141231 entry below for information about prerequisites and
	upgrading, if you are not already using clang 3.5.0 or higher.

20160301:
	The AIO subsystem is now a standard part of the kernel.  The
	VFS_AIO kernel option and aio.ko kernel module have been removed.
	Due to stability concerns, asynchronous I/O requests are only
	permitted on sockets and raw disks by default.  To enable
	asynchronous I/O requests on all file types, set the
	vfs.aio.enable_unsafe sysctl to a non-zero value.

20160226:
	The ELF object manipulation tool objcopy is now provided by the
	ELF Tool Chain project rather than by GNU binutils. It should be a
	drop-in replacement, with the addition of arm64 support. The
	(temporary) src.conf knob WITHOUT_ELFCOPY_AS_OBJCOPY knob may be set
	to obtain the GNU version if necessary.

20160129:
	Building ZFS pools on top of zvols is prohibited by default.  That
	feature has never worked safely; it's always been prone to deadlocks.
	Using a zvol as the backing store for a VM guest's virtual disk will
	still work, even if the guest is using ZFS.  Legacy behavior can be
	restored by setting vfs.zfs.vol.recursive=1.

20160119:
	The NONE and HPN patches has been removed from OpenSSH.  They are
	still available in the security/openssh-portable port.

20160113:
	With the addition of ypldap(8), a new _ypldap user is now required
	during installworld. "mergemaster -p" can be used to add the user
	prior to installworld, as documented in the handbook.

20151216:
	The tftp loader (pxeboot) now uses the option root-path directive. As a
	consequence it no longer looks for a pxeboot.4th file on the tftp
	server. Instead it uses the regular /boot infrastructure as with the
	other loaders.

20151211:
	The code to start recording plug and play data into the modules has
	been committed. While the old tools will properly build a new kernel,
	a number of warnings about "unknown metadata record 4" will be produced
	for an older kldxref. To avoid such warnings, make sure to rebuild
	the kernel toolchain (or world). Make sure that you have r292078 or
	later when trying to build 292077 or later before rebuilding.

20151207:
	Debug data files are now built by default with 'make buildworld' and
	installed with 'make installworld'. This facilitates debugging but
	requires more disk space both during the build and for the installed
	world. Debug files may be disabled by setting WITHOUT_DEBUG_FILES=yes
	in src.conf(5).

20151130:
	r291527 changed the internal interface between the nfsd.ko and
	nfscommon.ko modules. As such, they must both be upgraded to-gether.
	__FreeBSD_version has been bumped because of this.

20151108:
	Add support for unicode collation strings leads to a change of
	order of files listed by ls(1) for example. To get back to the old
	behaviour, set LC_COLLATE environment variable to "C".

	Databases administrators will need to reindex their databases given
	collation results will be different.

	Due to a bug in install(1) it is recommended to remove the ancient
	locales before running make installworld.

	rm -rf /usr/share/locale/*

20151030:
	The OpenSSL has been upgraded to 1.0.2d.  Any binaries requiring
	libcrypto.so.7 or libssl.so.7 must be recompiled.

20151020:
	Qlogic 24xx/25xx firmware images were updated from 5.5.0 to 7.3.0.
	Kernel modules isp_2400_multi and isp_2500_multi were removed and
	should be replaced with isp_2400 and isp_2500 modules respectively.

20151017:
	The build previously allowed using 'make -n' to not recurse into
	sub-directories while showing what commands would be executed, and
	'make -n -n' to recursively show commands.  Now 'make -n' will recurse
	and 'make -N' will not.

20151012:
	If you specify SENDMAIL_MC or SENDMAIL_CF in make.conf, mergemaster
	and etcupdate will now use this file. A custom sendmail.cf is now
	updated via this mechanism rather than via installworld.  If you had
	excluded sendmail.cf in mergemaster.rc or etcupdate.conf, you may
	want to remove the exclusion or change it to "always install".
	/etc/mail/sendmail.cf is now managed the same way regardless of
	whether SENDMAIL_MC/SENDMAIL_CF is used.  If you are not using
	SENDMAIL_MC/SENDMAIL_CF there should be no change in behavior.

20151011:
	Compatibility shims for legacy ATA device names have been removed.
	It includes ATA_STATIC_ID kernel option, kern.cam.ada.legacy_aliases
	and kern.geom.raid.legacy_aliases loader tunables, kern.devalias.*
	environment variables, /dev/ad* and /dev/ar* symbolic links.

20151006:
	Clang, llvm, lldb, compiler-rt and libc++ have been upgraded to 3.7.0.
	Please see the 20141231 entry below for information about prerequisites
	and upgrading, if you are not already using clang 3.5.0 or higher.

20150924:
	Kernel debug files have been moved to /usr/lib/debug/boot/kernel/,
	and renamed from .symbols to .debug. This reduces the size requirements
	on the boot partition or file system and provides consistency with
	userland debug files.

	When using the supported kernel installation method the
	/usr/lib/debug/boot/kernel directory will be renamed (to kernel.old)
	as is done with /boot/kernel.

	Developers wishing to maintain the historical behavior of installing
	debug files in /boot/kernel/ can set KERN_DEBUGDIR="" in src.conf(5).

20150827:
	The wireless drivers had undergone changes that remove the 'parent
	interface' from the ifconfig -l output. The rc.d network scripts
	used to check presence of a parent interface in the list, so old
	scripts would fail to start wireless networking. Thus, etcupdate(3)
	or mergemaster(8) run is required after kernel update, to update your
	rc.d scripts in /etc.

20150827:
	pf no longer supports 'scrub fragment crop' or 'scrub fragment drop-ovl'
	These configurations are now automatically interpreted as
	'scrub fragment reassemble'.

20150817:
	Kernel-loadable modules for the random(4) device are back. To use
	them, the kernel must have

	device	random
	options	RANDOM_LOADABLE

	kldload(8) can then be used to load random_fortuna.ko
	or random_yarrow.ko. Please note that due to the indirect
	function calls that the loadable modules need to provide,
	the build-in variants will be slightly more efficient.

	The random(4) kernel option RANDOM_DUMMY has been retired due to
	unpopularity. It was not all that useful anyway.

20150813:
	The WITHOUT_ELFTOOLCHAIN_TOOLS src.conf(5) knob has been retired.
	Control over building the ELF Tool Chain tools is now provided by
	the WITHOUT_TOOLCHAIN knob.

20150810:
	The polarity of Pulse Per Second (PPS) capture events with the
	uart(4) driver has been corrected.  Prior to this change the PPS
	"assert" event corresponded to the trailing edge of a positive PPS
	pulse and the "clear" event was the leading edge of the next pulse.

	As the width of a PPS pulse in a typical GPS receiver is on the
	order of 1 millisecond, most users will not notice any significant
	difference with this change.

	Anyone who has compensated for the historical polarity reversal by
	configuring a negative offset equal to the pulse width will need to
	remove that workaround.

20150809:
	The default group assigned to /dev/dri entries has been changed
	from 'wheel' to 'video' with the id of '44'. If you want to have
	access to the dri devices please add yourself to the video group
	with:

	# pw groupmod video -m $USER

20150806:
	The menu.rc and loader.rc files will now be replaced during
	upgrades. Please migrate local changes to menu.rc.local and
	loader.rc.local instead.

20150805:
	GNU Binutils versions of addr2line, c++filt, nm, readelf, size,
	strings and strip have been removed. The src.conf(5) knob
	WITHOUT_ELFTOOLCHAIN_TOOLS no longer provides the binutils tools.

20150728:
	As ZFS requires more kernel stack pages than is the default on some
	architectures e.g. i386, it now warns if KSTACK_PAGES is less than
	ZFS_MIN_KSTACK_PAGES (which is 4 at the time of writing).

	Please consider using 'options KSTACK_PAGES=X' where X is greater
	than or equal to ZFS_MIN_KSTACK_PAGES i.e. 4 in such configurations.

20150706:
	sendmail has been updated to 8.15.2.  Starting with FreeBSD 11.0
	and sendmail 8.15, sendmail uses uncompressed IPv6 addresses by
	default, i.e., they will not contain "::".  For example, instead
	of ::1, it will be 0:0:0:0:0:0:0:1.  This permits a zero subnet
	to have a more specific match, such as different map entries for
	IPv6:0:0 vs IPv6:0.  This change requires that configuration
	data (including maps, files, classes, custom ruleset, etc.) must
	use the same format, so make certain such configuration data is
	upgrading.  As a very simple check search for patterns like
	'IPv6:[0-9a-fA-F:]*::' and 'IPv6::'.  To return to the old
	behavior, set the m4 option confUSE_COMPRESSED_IPV6_ADDRESSES or
	the cf option UseCompressedIPv6Addresses.

20150630:
	The default kernel entropy-processing algorithm is now
	Fortuna, replacing Yarrow.

	Assuming you have 'device random' in your kernel config
	file, the configurations allow a kernel option to override
	this default. You may choose *ONE* of:

	options	RANDOM_YARROW	# Legacy /dev/random algorithm.
	options	RANDOM_DUMMY	# Blocking-only driver.

	If you have neither, you get Fortuna.  For most people,
	read no further, Fortuna will give a /dev/random that works
	like it always used to, and the difference will be irrelevant.

	If you remove 'device random', you get *NO* kernel-processed
	entropy at all. This may be acceptable to folks building
	embedded systems, but has complications. Carry on reading,
	and it is assumed you know what you need.

	*PLEASE* read random(4) and random(9) if you are in the
	habit of tweaking kernel configs, and/or if you are a member
	of the embedded community, wanting specific and not-usual
	behaviour from your security subsystems.

	NOTE!! If you use RANDOM_DUMMY and/or have no 'device
	random', you will NOT have a functioning /dev/random, and
	many cryptographic features will not work, including SSH.
	You may also find strange behaviour from the random(3) set
	of library functions, in particular sranddev(3), srandomdev(3)
	and arc4random(3). The reason for this is that the KERN_ARND
	sysctl only returns entropy if it thinks it has some to
	share, and with RANDOM_DUMMY or no 'device random' this
	will never happen.

20150623:
	An additional fix for the issue described in the 20150614 sendmail
	entry below has been committed in revision 284717.

20150616:
	FreeBSD's old make (fmake) has been removed from the system. It is
	available as the devel/fmake port or via pkg install fmake.

20150615:
	The fix for the issue described in the 20150614 sendmail entry
	below has been committed in revision 284436.  The work
	around described in that entry is no longer needed unless the
	default setting is overridden by a confDH_PARAMETERS configuration
	setting of '5' or pointing to a 512 bit DH parameter file.

20150614:
	ALLOW_DEPRECATED_ATF_TOOLS/ATFFILE support has been removed from
	atf.test.mk (included from bsd.test.mk). Please upgrade devel/atf
	and devel/kyua to version 0.20+ and adjust any calling code to work
	with Kyuafile and kyua.

20150614:
	The import of openssl to address the FreeBSD-SA-15:10.openssl
	security advisory includes a change which rejects handshakes
	with DH parameters below 768 bits.  sendmail releases prior
	to 8.15.2 (not yet released), defaulted to a 512 bit
	DH parameter setting for client connections.  To work around
	this interoperability, sendmail can be configured to use a
	2048 bit DH parameter by:

	1. Edit /etc/mail/`hostname`.mc
	2. If a setting for confDH_PARAMETERS does not exist or
	   exists and is set to a string beginning with '5',
	   replace it with '2'.
	3. If a setting for confDH_PARAMETERS exists and is set to
	   a file path, create a new file with:
		openssl dhparam -out /path/to/file 2048
	4. Rebuild the .cf file:
		cd /etc/mail/; make; make install
	5. Restart sendmail:
		cd /etc/mail/; make restart

	A sendmail patch is coming, at which time this file will be
	updated.

20150604:
	Generation of legacy formatted entries have been disabled by default
	in pwd_mkdb(8), as all base system consumers of the legacy formatted
	entries were converted to use the new format by default when the new,
	machine independent format have been added and supported since FreeBSD
	5.x.

	Please see the pwd_mkdb(8) manual page for further details.

20150525:
	Clang and llvm have been upgraded to 3.6.1 release.  Please see the
	20141231 entry below for information about prerequisites and upgrading,
	if you are not already using 3.5.0 or higher.

20150521:
	TI platform code switched to using vendor DTS files and this update
	may break existing systems running on Beaglebone, Beaglebone Black,
	and Pandaboard:

	- dtb files should be regenerated/reinstalled. Filenames are the
	  same but content is different now
	- GPIO addressing was changed, now each GPIO bank (32 pins per bank)
	  has its own /dev/gpiocX device, e.g. pin 121 on /dev/gpioc0 in old
	  addressing scheme is now pin 25 on /dev/gpioc3.
	- Pandaboard: /etc/ttys should be updated, serial console device is
	  now /dev/ttyu2, not /dev/ttyu0

20150501:
	soelim(1) from gnu/usr.bin/groff has been replaced by usr.bin/soelim.
	If you need the GNU extension from groff soelim(1), install groff
	from package: pkg install groff, or via ports: textproc/groff.

20150423:
	chmod, chflags, chown and chgrp now affect symlinks in -R mode as
	defined in symlink(7); previously symlinks were silently ignored.

20150415:
	The const qualifier has been removed from iconv(3) to comply with
	POSIX.  The ports tree is aware of this from r384038 onwards.

20150416:
	Libraries specified by LIBADD in Makefiles must have a corresponding
	DPADD_<lib> variable to ensure correct dependencies.  This is now
	enforced in src.libnames.mk.

20150324:
	From legacy ata(4) driver was removed support for SATA controllers
	supported by more functional drivers ahci(4), siis(4) and mvs(4).
	Kernel modules ataahci and ataadaptec were removed completely,
	replaced by ahci and mvs modules respectively.

20150315:
	Clang, llvm and lldb have been upgraded to 3.6.0 release.  Please see
	the 20141231 entry below for information about prerequisites and
	upgrading, if you are not already using 3.5.0 or higher.

20150307:
	The 32-bit PowerPC kernel has been changed to a position-independent
	executable. This can only be booted with a version of loader(8)
	newer than January 31, 2015, so make sure to update both world and
	kernel before rebooting.

20150217:
	If you are running a -CURRENT kernel since r273872 (Oct 30th, 2014),
	but before r278950, the RNG was not seeded properly.  Immediately
	upgrade the kernel to r278950 or later and regenerate any keys (e.g.
	ssh keys or openssl keys) that were generated w/ a kernel from that
	range.  This does not affect programs that directly used /dev/random
	or /dev/urandom.  All userland uses of arc4random(3) are affected.

20150210:
	The autofs(4) ABI was changed in order to restore binary compatibility
	with 10.1-RELEASE.  The automountd(8) daemon needs to be rebuilt to work
	with the new kernel.

20150131:
	The powerpc64 kernel has been changed to a position-independent
	executable. This can only be booted with a new version of loader(8),
	so make sure to update both world and kernel before rebooting.

20150118:
	Clang and llvm have been upgraded to 3.5.1 release.  This is a bugfix
	only release, no new features have been added.  Please see the 20141231
	entry below for information about prerequisites and upgrading, if you
	are not already using 3.5.0.

20150107:
	ELF tools addr2line, elfcopy (strip), nm, size, and strings are now
	taken from the ELF Tool Chain project rather than GNU binutils. They
	should be drop-in replacements, with the addition of arm64 support.
	The WITHOUT_ELFTOOLCHAIN_TOOLS= knob may be used to obtain the
	binutils tools, if necessary. See 20150805 for updated information.

20150105:
	The default Unbound configuration now enables remote control
	using a local socket.  Users who have already enabled the
	local_unbound service should regenerate their configuration
	by running "service local_unbound setup" as root.

20150102:
	The GNU texinfo and GNU info pages have been removed.
	To be able to view GNU info pages please install texinfo from ports.

20141231:
	Clang, llvm and lldb have been upgraded to 3.5.0 release.

	As of this release, a prerequisite for building clang, llvm and lldb is
	a C++11 capable compiler and C++11 standard library.  This means that to
	be able to successfully build the cross-tools stage of buildworld, with
	clang as the bootstrap compiler, your system compiler or cross compiler
	should either be clang 3.3 or later, or gcc 4.8 or later, and your
	system C++ library should be libc++, or libdstdc++ from gcc 4.8 or
	later.

	On any standard FreeBSD 10.x or 11.x installation, where clang and
	libc++ are on by default (that is, on x86 or arm), this should work out
	of the box.

	On 9.x installations where clang is enabled by default, e.g. on x86 and
	powerpc, libc++ will not be enabled by default, so libc++ should be
	built (with clang) and installed first.  If both clang and libc++ are
	missing, build clang first, then use it to build libc++.

	On 8.x and earlier installations, upgrade to 9.x first, and then follow
	the instructions for 9.x above.

	Sparc64 and mips users are unaffected, as they still use gcc 4.2.1 by
	default, and do not build clang.

	Many embedded systems are resource constrained, and will not be able to
	build clang in a reasonable time, or in some cases at all.  In those
	cases, cross building bootable systems on amd64 is a workaround.

	This new version of clang introduces a number of new warnings, of which
	the following are most likely to appear:

	-Wabsolute-value

	This warns in two cases, for both C and C++:
	* When the code is trying to take the absolute value of an unsigned
	  quantity, which is effectively a no-op, and almost never what was
	  intended.  The code should be fixed, if at all possible.  If you are
	  sure that the unsigned quantity can be safely cast to signed, without
	  loss of information or undefined behavior, you can add an explicit
	  cast, or disable the warning.

	* When the code is trying to take an absolute value, but the called
	  abs() variant is for the wrong type, which can lead to truncation.
	  If you want to disable the warning instead of fixing the code, please
	  make sure that truncation will not occur, or it might lead to unwanted
	  side-effects.

	-Wtautological-undefined-compare and
	-Wundefined-bool-conversion

	These warn when C++ code is trying to compare 'this' against NULL, while
	'this' should never be NULL in well-defined C++ code.  However, there is
	some legacy (pre C++11) code out there, which actively abuses this
	feature, which was less strictly defined in previous C++ versions.

	Squid and openjdk do this, for example.  The warning can be turned off
	for C++98 and earlier, but compiling the code in C++11 mode might result
	in unexpected behavior; for example, the parts of the program that are
	unreachable could be optimized away.

20141222:
	The old NFS client and server (kernel options NFSCLIENT, NFSSERVER)
	kernel sources have been removed. The .h files remain, since some
	utilities include them. This will need to be fixed later.
	If "mount -t oldnfs ..." is attempted, it will fail.
	If the "-o" option on mountd(8), nfsd(8) or nfsstat(1) is used,
	the utilities will report errors.

20141121:
	The handling of LOCAL_LIB_DIRS has been altered to skip addition of
	directories to top level SUBDIR variable when their parent
	directory is included in LOCAL_DIRS.  Users with build systems with
	such hierarchies and without SUBDIR entries in the parent
	directory Makefiles should add them or add the directories to
	LOCAL_DIRS.

20141109:
	faith(4) and faithd(8) have been removed from the base system. Faith
	has been obsolete for a very long time.

20141104:
	vt(4), the new console driver, is enabled by default. It brings
	support for Unicode and double-width characters, as well as
	support for UEFI and integration with the KMS kernel video
	drivers.

	You may need to update your console settings in /etc/rc.conf,
	most probably the keymap. During boot, /etc/rc.d/syscons will
	indicate what you need to do.

	vt(4) still has issues and lacks some features compared to
	syscons(4). See the wiki for up-to-date information:
	  https://wiki.freebsd.org/Newcons

	If you want to keep using syscons(4), you can do so by adding
	the following line to /boot/loader.conf:
	  kern.vty=sc

20141102:
	pjdfstest has been integrated into kyua as an opt-in test suite.
	Please see share/doc/pjdfstest/README for more details on how to
	execute it.

20141009:
	gperf has been removed from the base system for architectures
	that use clang. Ports that require gperf will obtain it from the
	devel/gperf port.

20140923:
	pjdfstest has been moved from tools/regression/pjdfstest to
	contrib/pjdfstest .

20140922:
	At svn r271982, The default linux compat kernel ABI has been adjusted
	to 2.6.18 in support of the linux-c6 compat ports infrastructure
	update.  If you wish to continue using the linux-f10 compat ports,
	add compat.linux.osrelease=2.6.16 to your local sysctl.conf.  Users are
	encouraged to update their linux-compat packages to linux-c6 during
	their next update cycle.

20140729:
	The ofwfb driver, used to provide a graphics console on PowerPC when
	using vt(4), no longer allows mmap() of all physical memory. This
	will prevent Xorg on PowerPC with some ATI graphics cards from
	initializing properly unless x11-servers/xorg-server is updated to
	1.12.4_8 or newer.

20140723:
	The xdev targets have been converted to using TARGET and
	TARGET_ARCH instead of XDEV and XDEV_ARCH.

20140719:
	The default unbound configuration has been modified to address
	issues with reverse lookups on networks that use private
	address ranges.  If you use the local_unbound service, run
	"service local_unbound setup" as root to regenerate your
	configuration, then "service local_unbound reload" to load the
	new configuration.

20140709:
	The GNU texinfo and GNU info pages are not built and installed
	anymore, WITH_INFO knob has been added to allow to built and install
	them again.
	UPDATE: see 20150102 entry on texinfo's removal

20140708:
	The GNU readline library is now an INTERNALLIB - that is, it is
	statically linked into consumers (GDB and variants) in the base
	system, and the shared library is no longer installed.  The
	devel/readline port is available for third party software that
	requires readline.

20140702:
	The Itanium architecture (ia64) has been removed from the list of
	known architectures. This is the first step in the removal of the
	architecture.

20140701:
	Commit r268115 has added NFSv4.1 server support, merged from
	projects/nfsv4.1-server.  Since this includes changes to the
	internal interfaces between the NFS related modules, a full
	build of the kernel and modules will be necessary.
	__FreeBSD_version has been bumped.

20140629:
	The WITHOUT_VT_SUPPORT kernel config knob has been renamed
	WITHOUT_VT.  (The other _SUPPORT knobs have a consistent meaning
	which differs from the behaviour controlled by this knob.)

20140619:
	Maximal length of the serial number in CTL was increased from 16 to
	64 chars, that breaks ABI.  All CTL-related tools, such as ctladm
	and ctld, need to be rebuilt to work with a new kernel.

20140606:
	The libatf-c and libatf-c++ major versions were downgraded to 0 and
	1 respectively to match the upstream numbers.  They were out of
	sync because, when they were originally added to FreeBSD, the
	upstream versions were not respected.  These libraries are private
	and not yet built by default, so renumbering them should be a
	non-issue.  However, unclean source trees will yield broken test
	programs once the operator executes "make delete-old-libs" after a
	"make installworld".

	Additionally, the atf-sh binary was made private by moving it into
	/usr/libexec/.  Already-built shell test programs will keep the
	path to the old binary so they will break after "make delete-old"
	is run.

	If you are using WITH_TESTS=yes (not the default), wipe the object
	tree and rebuild from scratch to prevent spurious test failures.
	This is only needed once: the misnumbered libraries and misplaced
	binaries have been added to OptionalObsoleteFiles.inc so they will
	be removed during a clean upgrade.

20140512:
	Clang and llvm have been upgraded to 3.4.1 release.

20140508:
	We bogusly installed src.opts.mk in /usr/share/mk. This file should
	be removed to avoid issues in the future (and has been added to
	ObsoleteFiles.inc).

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... In cases where MAKESYSPATH isn't working with this
	setting, you'll need to set it to the full path to your tree.

	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.

20140424:
	The knob WITHOUT_VI was added to the base system, which controls
	building ex(1), vi(1), etc. Older releases of FreeBSD required ex(1)
	in order to reorder files share/termcap and didn't build ex(1) as a
	build tool, so building/installing with WITH_VI is highly advised for
	build hosts for older releases.

	This issue has been fixed in stable/9 and stable/10 in r277022 and
	r276991, respectively.

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 stable/10 branch has been created in subversion from head
	revision r256279.

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
	compatibility.  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.)

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 if you encounter problems with a major version upgrade.  Since
	the stable 4.x branch point, one has generally been able to upgrade from
	anywhere in the most recent stable branch to head / current (or even the
	last couple of stable branches). See the top of this file when there's
	an exception.

	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.

	This file should be read as a log of events. When a later event changes
	information of a prior event, the prior event should not be deleted.
	Instead, a pointer to the entry with the new information should be
	placed in the old entry. Readers of this file should also sanity check
	older entries before relying on them blindly. Authors of new entries
	should write them with this in mind.

	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 ada0:
	"gpart bootcode -p /boot/gptzfsboot -i 1 ada0"

	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 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 buildkernel KERNCONF=YOUR_KERNEL_HERE
	make installkernel 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 no-op.  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] 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 September 23, 2011.
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.

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modification, in full or in part, in any form or format of this
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DISCLAIMED.  IN NO EVENT SHALL WARNER LOSH BE LIABLE FOR ANY DIRECT,
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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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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$FreeBSD$