xref: /freebsd/UPDATING (revision 7e06afcad35f276ab0fd1c9c29888db2834ee9d8)

Updating Information for FreeBSD current users

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

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

NOTE TO PEOPLE WHO THINK THAT FreeBSD 8.x IS SLOW:
	FreeBSD 8.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 disable malloc debugging, run
	ln -s aj /etc/malloc.conf.)

20090313:
	POSIX.1 Native Language Support (NLS) has been enabled in libc and
	a bunch of new language catalog files have also been added.
	This means that some common libc messages are now localized and
	they depend on the LC_MESSAGES environmental variable.

20090313:
	The k8temp(4) driver has been renamed to amdtemp(4) since
	support for K10 and K11 CPU families was added.

20090309:
	IGMPv3 and Source-Specific Multicast (SSM) have been merged
	to the IPv4 stack. VIMAGE hooks are in but not yet used.

	For kernel developers, the most important changes are that the
	ip_output() and ip_input() paths no longer take the IN_MULTI_LOCK(),
	and this lock has been downgraded to a non-recursive mutex.

	Transport protocols (UDP, Raw IP) are now responsible for filtering
	inbound multicast traffic according to group membership and source
	filters. The imo_multicast_filter() KPI exists for this purpose.
	Transports which do not use multicast (SCTP, TCP) already reject
	multicast by default. Forwarding and receive performance may improve
	as a mutex acquisition is no longer needed in the ip_input()
	low-level input path.  in_addmulti() and in_delmulti() are shimmed
	to new KPIs which exist to support SSM in-kernel.

	For application developers, it is recommended that loopback of
	multicast datagrams be disabled for best performance, as this
	will still cause the lock to be taken for each looped-back
	datagram transmission. The net.inet.ip.mcast.loop sysctl may
	be tuned to 0 to disable loopback by default; it defaults to 1
	to preserve the existing behaviour.

	For systems administrators, to obtain best performance with
	multicast reception and multiple groups, it is always recommended
	that a card with a suitably precise hash filter is used. Hash
	collisions will still result in the lock being taken within the
	transport protocol input path to check group membership.

	If deploying FreeBSD in an environment with IGMP snooping switches,
	it is recommended that the net.inet.igmp.sendlocal sysctl remain
	enabled; this forces 224.0.0.0/24 group membership to be announced
	via IGMP.

	The size of 'struct igmpstat' has changed; netstat needs to be
	recompiled to reflect this.
	Bump __FreeBSD_version to 800070.

20090309:
	libusb20.so.1 is now installed as libusb.so.1 and the ports system
	updated to use it. This requires a buildworld/installworld in order to
	update the library and dependencies (usbconfig, etc). Its advisable to
	rebuild all ports which uses libusb. More specific directions are given
	in the ports collection UPDATING file. Any /etc/libmap.conf entries for
	libusb are no longer required and can be removed.

20090302:
	A workaround is committed to allow the creation of System V shared
	memory segment of size > 2 GB on the 64-bit architectures.
	Due to a limitation of the existing ABI, the shm_segsz member
	of the struct shmid_ds, returned by shmctl(IPC_STAT) call is
	wrong for large segments. Note that limits must be explicitely
	raised to allow such segments to be created.

20090301:
	The layout of struct ifnet has changed, requiring a rebuild of all
	network device driver modules.

20090227:
	The /dev handling for the new USB stack has changed, a
	buildworld/installworld is required for libusb20.

20090223:
	The new USB2 stack has now been permanently moved in and all kernel and
	module names reverted to their previous values (eg, usb, ehci, ohci,
	ums, ...).  The old usb stack can be compiled in by prefixing the name
	with the letter 'o', the old usb modules have been removed.
	Updating entry 20090216 for xorg and 20090215 for libmap may still
	apply.

20090217:
	The rc.conf(5) option if_up_delay has been renamed to
	defaultroute_delay to better reflect its purpose. If you have
	customized this setting in /etc/rc.conf you need to update it to
	use the new name.

20090216:
	xorg 7.4 wants to configure its input devices via hald which does not
	yet work with USB2. If the keyboard/mouse does not work in xorg then
	add
		Option "AllowEmptyInput" "off"
	to your ServerLayout section.  This will cause X to use the configured
	kbd and mouse sections from your xorg.conf.

20090215:
	The GENERIC kernels for all architectures now default to the new USB2
	stack. No kernel config options or code have been removed so if a
	problem arises please report it and optionally revert to the old USB
	stack. If you are loading USB kernel modules or have a custom kernel
	that includes GENERIC then ensure that usb names are also changed over,
	eg uftdi -> usb2_serial_ftdi.

	Older programs linked against the ports libusb 0.1 need to be
	redirected to the new stack's libusb20.  /etc/libmap.conf can
	be used for this:
		# Map old usb library to new one for usb2 stack
		libusb-0.1.so.8	libusb20.so.1

20090203:
	The ichsmb(4) driver has been changed to require SMBus slave
	addresses be left-justified (xxxxxxx0b) rather than right-justified.
	All of the other SMBus controller drivers require left-justified
	slave addresses, so this change makes all the drivers provide the
	same interface.

20090201:
	INET6 statistics (struct ip6stat) was updated.
	netstat(1) needs to be recompiled.

20090119:
	NTFS has been removed from GENERIC kernel on amd64 to match
	GENERIC on i386. Should not cause any issues since mount_ntfs(8)
	will load ntfs.ko module automatically when NTFS support is
	actually needed, unless ntfs.ko is not installed or security
	level prohibits loading kernel modules. If either is the case,
	"options NTFS" has to be added into kernel config.

20090115:
	TCP Appropriate Byte Counting (RFC 3465) support added to kernel.
	New field in struct tcpcb breaks ABI, so bump __FreeBSD_version to
	800061. User space tools that rely on the size of struct tcpcb in
	tcp_var.h (e.g. sockstat) need to be recompiled.

20081225:
	ng_tty(4) module updated to match the new TTY subsystem.
	Due to API change, user-level applications must be updated.
	New API support added to mpd5 CVS and expected to be present
	in next mpd5.3 release.

20081219:
	With __FreeBSD_version 800060 the makefs tool is part of
	the base system (it was a port).

20081216:
	The afdata and ifnet locks have been changed from mutexes to
	rwlocks, network modules will need to be re-compiled.

20081214:
	__FreeBSD_version 800059 incorporates the new arp-v2 rewrite.
	RTF_CLONING, RTF_LLINFO and RTF_WASCLONED flags are eliminated.
	The new code reduced struct rtentry{} by 16 bytes on 32-bit
	architecture and 40 bytes on 64-bit architecture. The userland
	applications "arp" and "ndp" have been updated accordingly.
	The output from "netstat -r" shows only routing entries and
	none of the L2 information.

20081130:
	__FreeBSD_version 800057 marks the switchover from the
	binary ath hal to source code. Users must add the line:

	options	AH_SUPPORT_AR5416

	to their kernel config files when specifying:

	device	ath_hal

	The ath_hal module no longer exists; the code is now compiled
	together with the driver in the ath module.  It is now
	possible to tailor chip support (i.e. reduce the set of chips
	and thereby the code size); consult ath_hal(4) for details.

20081121:
	__FreeBSD_version 800054 adds memory barriers to
	<machine/atomic.h>, new interfaces to ifnet to facilitate
	multiple hardware transmit queues for cards that support
	them, and a lock-less ring-buffer implementation to
	enable drivers to more efficiently manage queueing of
	packets.

20081117:
	A new version of ZFS (version 13) has been merged to -HEAD.
	This version has zpool attribute "listsnapshots" off by
	default, which means "zfs list" does not show snapshots,
	and is the same as Solaris behavior.

20081028:
	dummynet(4) ABI has changed. ipfw(8) needs to be recompiled.

20081009:
	The uhci, ohci, ehci and slhci USB Host controller drivers have
	been put into separate modules. If you load the usb module
	separately through loader.conf you will need to load the
	appropriate *hci module as well. E.g. for a UHCI-based USB 2.0
	controller add the following to loader.conf:

		uhci_load="YES"
		ehci_load="YES"

20081009:
	The ABI used by the PMC toolset has changed.  Please keep
	userland (libpmc(3)) and the kernel module (hwpmc(4)) in
	sync.

20080820:
	The TTY subsystem of the kernel has been replaced by a new
	implementation, which provides better scalability and an
	improved driver model. Most common drivers have been migrated to
	the new TTY subsystem, while others have not. The following
	drivers have not yet been ported to the new TTY layer:

	PCI/ISA:
		cy, digi, rc, rp, sio

	USB:
		ubser, ucycom

	Line disciplines:
		ng_h4, ng_tty, ppp, sl, snp

	Adding these drivers to your kernel configuration file shall
	cause compilation to fail.

20080818:
	ntpd has been upgraded to 4.2.4p5.

20080801:
	OpenSSH has been upgraded to 5.1p1.

	For many years, FreeBSD's version of OpenSSH preferred DSA
	over RSA for host and user authentication keys.  With this
	upgrade, we've switched to the vendor's default of RSA over
	DSA.  This may cause upgraded clients to warn about unknown
	host keys even for previously known hosts.  Users should
	follow the usual procedure for verifying host keys before
	accepting the RSA key.

	This can be circumvented by setting the "HostKeyAlgorithms"
	option to "ssh-dss,ssh-rsa" in ~/.ssh/config or on the ssh
	command line.

	Please note that the sequence of keys offered for
	authentication has been changed as well.  You may want to
	specify IdentityFile in a different order to revert this
	behavior.

20080713:
	The sio(4) driver has been removed from the i386 and amd64
	kernel configuration files. This means uart(4) is now the
	default serial port driver on those platforms as well.

	To prevent collisions with the sio(4) driver, the uart(4) driver
	uses different names for its device nodes. This means the
	onboard serial port will now most likely be called "ttyu0"
	instead of "ttyd0". You may need to reconfigure applications to
	use the new device names.

	When using the serial port as a boot console, be sure to update
	/boot/device.hints and /etc/ttys before booting the new kernel.
	If you forget to do so, you can still manually specify the hints
	at the loader prompt:

		set hint.uart.0.at="isa"
		set hint.uart.0.port="0x3F8"
		set hint.uart.0.flags="0x10"
		set hint.uart.0.irq="4"
		boot -s

20080609:
	The gpt(8) utility has been removed. Use gpart(8) to partition
	disks instead.

20080603:
	The version that Linuxulator emulates was changed from 2.4.2
	to 2.6.16. If you experience any problems with Linux binaries
	please try to set sysctl compat.linux.osrelease to 2.4.2 and
	if it fixes the problem contact emulation mailing list.

20080525:
	ISDN4BSD (I4B) was removed from the src tree. You may need to
	update a your kernel configuration and remove relevant entries.

20080509:
	I have checked in code to support multiple routing tables.
	See the man pages setfib(1) and setfib(2).
	This is a hopefully backwards compatible version,
	but to make use of it you need to compile your kernel
	with options ROUTETABLES=2 (or more up to 16).

20080420:
	The 802.11 wireless support was redone to enable multi-bss
	operation on devices that are capable.  The underlying device
	is no longer used directly but instead wlanX devices are
	cloned with ifconfig.  This requires changes to rc.conf files.
	For example, change:
		ifconfig_ath0="WPA DHCP"
	to
		wlans_ath0=wlan0
		ifconfig_wlan0="WPA DHCP"
	see rc.conf(5) for more details.  In addition, mergemaster of
	/etc/rc.d is highly recommended.  Simultaneous update of userland
	and kernel wouldn't hurt either.

	As part of the multi-bss changes the wlan_scan_ap and wlan_scan_sta
	modules were merged into the base wlan module.  All references
	to these modules (e.g. in kernel config files) must be removed.

20080408:
	psm(4) has gained write(2) support in native operation level.
	Arbitrary commands can be written to /dev/psm%d and status can
	be read back from it.  Therefore, an application is responsible
	for status validation and error recovery.  It is a no-op in
	other operation levels.

20080312:
	Support for KSE threading has been removed from the kernel.  To
	run legacy applications linked against KSE libmap.conf may
	be used.  The following libmap.conf may be used to ensure
	compatibility with any prior release:

	libpthread.so.1 libthr.so.1
	libpthread.so.2 libthr.so.2
	libkse.so.3 libthr.so.3

20080301:
	The layout of struct vmspace has changed. This affects libkvm
	and any executables that link against libkvm and use the
	kvm_getprocs() function. In particular, but not exclusively,
	it affects ps(1), fstat(1), pkill(1), systat(1), top(1) and w(1).
	The effects are minimal, but it's advisable to upgrade world
	nonetheless.

20080229:
	The latest em driver no longer has support in it for the
	82575 adapter, this is now moved to the igb driver. The
	split was done to make new features that are incompatible
	with older hardware easier to do.

20080220:
	The new geom_lvm(4) geom class has been renamed to geom_linux_lvm(4),
	likewise the kernel option is now GEOM_LINUX_LVM.

20080211:
	The default NFS mount mode has changed from UDP to TCP for
	increased reliability.  If you rely on (insecurely) NFS
	mounting across a firewall you may need to update your
	firewall rules.

20080208:
	Belatedly note the addition of m_collapse for compacting
	mbuf chains.

20080126:
	The fts(3) structures have been changed to use adequate
	integer types for their members and so to be able to cope
	with huge file trees.  The old fts(3) ABI is preserved
	through symbol versioning in libc, so third-party binaries
	using fts(3) should still work, although they will not take
	advantage of the extended types.  At the same time, some
	third-party software might fail to build after this change
	due to unportable assumptions made in its source code about
	fts(3) structure members.  Such software should be fixed
	by its vendor or, in the worst case, in the ports tree.
	FreeBSD_version 800015 marks this change for the unlikely
	case that a portable fix is impossible.

20080123:
	To upgrade to -current after this date, you must be running
	FreeBSD not older than 6.0-RELEASE.  Upgrading to -current
	from 5.x now requires a stop over at RELENG_6 or RELENG_7 systems.

20071128:
	The ADAPTIVE_GIANT kernel option has been retired because its
	functionality is the default now.

20071118:
	The AT keyboard emulation of sunkbd(4) has been turned on
	by default. In order to make the special symbols of the Sun
	keyboards driven by sunkbd(4) work under X these now have
	to be configured the same way as Sun USB keyboards driven
	by ukbd(4) (which also does AT keyboard emulation), f.e.:

	Option	"XkbLayout" "us"
	Option	"XkbRules" "xorg"
	Option	"XkbSymbols" "pc(pc105)+sun_vndr/usb(sun_usb)+us"

20071024:
	It has been decided that it is desirable to provide ABI
	backwards compatibility to the FreeBSD 4/5/6 versions of the
	PCIOCGETCONF, PCIOCREAD and PCIOCWRITE IOCTLs, which was
	broken with the introduction of PCI domain support (see the
	20070930 entry). Unfortunately, this required the ABI of
	PCIOCGETCONF to be broken again in order to be able to
	provide backwards compatibility to the old version of that
	IOCTL. Thus consumers of PCIOCGETCONF have to be recompiled
	again. As for prominent ports this affects neither pciutils
	nor xorg-server this time, the hal port needs to be rebuilt
	however.

20071020:
	The misnamed kthread_create() and friends have been renamed
	to kproc_create() etc. Many of the callers already
	used kproc_start()..
	I will return kthread_create() and friends in a while
	with implementations that actually create threads, not procs.
	Renaming corresponds with version 800002.

20071010:
	RELENG_7 branched.

20071009:
	Setting WITHOUT_LIBPTHREAD now means WITHOUT_LIBKSE and
	WITHOUT_LIBTHR are set.

20070930:
	The PCI code has been made aware of PCI domains. This means that
	the location strings as used by pciconf(8) etc are now in the
	following format: pci<domain>:<bus>:<device>[:<function>]. It
	also means that consumers of <sys/pciio.h> potentially need to
	be recompiled; this includes the hal and xorg-server ports.

20070928:
	The caching daemon (cached) was renamed to nscd. nscd.conf
	configuration file should be used instead of cached.conf and
	nscd_enable, nscd_pidfile and nscd_flags options should be used
	instead of cached_enable, cached_pidfile and cached_flags in
	rc.conf.

20070921:
	The getfacl(1) utility now prints owning user and group name
	instead of owning uid and gid in the three line comment header.
	This is the same behavior as getfacl(1) on Solaris and Linux.

20070704:
	The new IPsec code is now compiled in using the IPSEC option.  The
	IPSEC option now requires "device crypto" be defined in your kernel
	configuration.  The FAST_IPSEC kernel option is now deprecated.

20070702:
	The packet filter (pf) code has been updated to OpenBSD 4.1 Please
	note the changed syntax - keep state is now on by default.  Also
	note the fact that ftp-proxy(8) has been changed from bottom up and
	has been moved from libexec to usr/sbin.  Changes in the ALTQ
	handling also affect users of IPFW's ALTQ capabilities.

20070701:
	Remove KAME IPsec in favor of FAST_IPSEC, which is now the
	only IPsec supported by FreeBSD.  The new IPsec stack
	supports both IPv4 and IPv6. The kernel option will change
	after the code changes have settled in.  For now the kernel
	option IPSEC is deprecated and FAST_IPSEC is the only option, that
	will change after some settling time.

20070701:
	The wicontrol(8) utility has been removed from the base system. wi(4)
	cards should be configured using ifconfig(8), see the man page for more
	information.

20070612:
	The i386/amd64 GENERIC kernel now defaults to the nfe(4) driver
	instead of the nve(4) driver. Please update your configuration
	accordingly.

20070612:
	By default, /etc/rc.d/sendmail no longer rebuilds the aliases
	database if it is missing or older than the aliases file.  If
	desired, set the new rc.conf option sendmail_rebuild_aliases
	to "YES" to restore that functionality.

20070612:
	The IPv4 multicast socket code has been considerably modified, and
	moved to the file sys/netinet/in_mcast.c. Initial support for the
	RFC 3678 Source-Specific Multicast Socket API has been added to
	the IPv4 network stack.

	Strict multicast and broadcast reception is now the default for
	UDP/IPv4 sockets; the net.inet.udp.strict_mcast_mship sysctl variable
	has now been removed.

	The RFC 1724 hack for interface selection has been removed; the use
	of the Linux-derived ip_mreqn structure with IP_MULTICAST_IF has
	been added to replace it. Consumers such as routed will soon be
	updated to reflect this.

	These changes affect users who are running routed(8) or rdisc(8)
	from the FreeBSD base system on point-to-point or unnumbered
	interfaces.

20070610:
	The net80211 layer has changed significantly and all wireless
	drivers that depend on it need to be recompiled.  Further these
	changes require that any program that interacts with the wireless
	support in the kernel be recompiled; this includes: ifconfig,
	wpa_supplicant, hostapd, and wlanstats.  Users must also, for
	the moment, kldload the wlan_scan_sta and/or wlan_scan_ap modules
	if they use modules for wireless support.  These modules implement
	scanning support for station and ap modes, respectively.  Failure
	to load the appropriate module before marking a wireless interface
	up will result in a message to the console and the device not
	operating properly.

20070610:
	The pam_nologin(8) module ceases to provide an authentication
	function and starts providing an account management function.
	Consequent changes to /etc/pam.d should be brought in using
	mergemaster(8).  Third-party files in /usr/local/etc/pam.d may
	need manual editing as follows.  Locate this line (or similar):

		auth	required	pam_nologin.so	no_warn

	and change it according to this example:

		account	required	pam_nologin.so	no_warn

	That is, the first word needs to be changed from "auth" to
	"account".  The new line can be moved to the account section
	within the file for clarity.  Not updating pam.conf(5) files
	will result in nologin(5) ignored by the respective services.

20070529:
	The ether_ioctl() function has been synchronized with ioctl(2)
	and ifnet.if_ioctl.  Due to that, the size of one of its arguments
	has changed on 64-bit architectures.  All kernel modules using
	ether_ioctl() need to be rebuilt on such architectures.

20070516:
	Improved INCLUDE_CONFIG_FILE support has been introduced to the
	config(8) utility. In order to take advantage of this new
	functionality, you are expected to recompile and install
	src/usr.sbin/config. If you don't rebuild config(8), and your
	kernel configuration depends on INCLUDE_CONFIG_FILE, the kernel
	build will be broken because of a missing "kernconfstring"
	symbol.

20070513:
	Symbol versioning is enabled by default.  To disable it, use
	option WITHOUT_SYMVER.  It is not advisable to attempt to
	disable symbol versioning once it is enabled; your installworld
	will break because a symbol version-less libc will get installed
	before the install tools.  As a result, the old install tools,
	which previously had symbol dependencies to FBSD_1.0, will fail
	because the freshly installed libc will not have them.

	The default threading library (providing "libpthread") has been
	changed to libthr.  If you wish to have libkse as your default,
	use option DEFAULT_THREAD_LIB=libkse for the buildworld.

20070423:
	The ABI breakage in sendmail(8)'s libmilter has been repaired
	so it is no longer necessary to recompile mail filters (aka,
	milters).  If you recompiled mail filters after the 20070408
	note, it is not necessary to recompile them again.

20070417:
	The new trunk(4) driver has been renamed to lagg(4) as it better
	reflects its purpose. ifconfig will need to be recompiled.

20070408:
	sendmail(8) has been updated to version 8.14.1.  Mail filters
	(aka, milters) compiled against the libmilter included in the
	base operating system should be recompiled.

20070302:
	Firmwares for ipw(4) and iwi(4) are now included in the base tree.
	In order to use them one must agree to the respective LICENSE in
	share/doc/legal and define legal.intel_<name>.license_ack=1 via
	loader.conf(5) or kenv(1).  Make sure to deinstall the now
	deprecated modules from the respective firmware ports.

20070228:
	The name resolution/mapping functions addr2ascii(3) and ascii2addr(3)
	were removed from FreeBSD's libc. These originally came from INRIA
	IPv6. Nothing in FreeBSD ever used them. They may be regarded as
	deprecated in previous releases.
	The AF_LINK support for getnameinfo(3) was merged from NetBSD to
	replace it as a more portable (and re-entrant) API.

20070224:
	To support interrupt filtering a modification to the newbus API
	has occurred, ABI was broken and __FreeBSD_version was bumped
	to 700031. Please make sure that your kernel and modules are in
	sync. For more info:
	http://docs.freebsd.org/cgi/mid.cgi?20070221233124.GA13941

20070224:
	The IPv6 multicast forwarding code may now be loaded into GENERIC
	kernels by loading the ip_mroute.ko module. This is built into the
	module unless WITHOUT_INET6 or WITHOUT_INET6_SUPPORT options are
	set; see src.conf(5) for more information.

20070214:
	The output of netstat -r has changed. Without -n, we now only
	print a "network name" without the prefix length if the network
	address and mask exactly match a Class A/B/C network, and an entry
	exists in the nsswitch "networks" map.
	With -n, we print the full unabbreviated CIDR network prefix in
	the form "a.b.c.d/p". 0.0.0.0/0 is always printed as "default".
	This change is in preparation for changes such as equal-cost
	multipath, and to more generally assist operational deployment
	of FreeBSD as a modern IPv4 router.

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

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

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

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

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

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

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

20061122:
	geom(4)'s gmirror(8) class metadata structure has been
	rev'd from v3 to v4. If you update across this point and
	your metadata is converted for you, you will not be easily
	able to downgrade since the /boot/kernel.old/geom_mirror.ko
	kernel module will be unable to read the v4 metadata.  You
	can resolve this by doing from the loader(8) prompt:

		set vfs.root.mountfrom="ufs:/dev/XXX"

	where XXX is the root slice of one of the disks that composed
	the mirror (i.e.: /dev/ad0s1a). You can then rebuild
	the array the same way you built it originally.

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

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

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

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

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

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

20060924:
	tcpslice has been removed from the base system.

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

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

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

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

20060709:
	The interface version of the i4b kernel part has changed. So
	after updating the kernel sources and compiling a new kernel,
	the i4b user space tools in "/usr/src/usr.sbin/i4b" must also
	be rebuilt, and vice versa.

20060627:
	The XBOX kernel now defaults to the nfe(4) driver instead of
	the nve(4) driver. Please update your configuration
	accordingly.

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

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

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

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

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

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

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

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

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

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

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

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

20060201:
	The kernel ABI to file system modules was changed on i386.
	Please make sure that your kernel and modules are in sync.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

20050711:
	RELENG_6 branched here.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

20041104:
	FreeBSD 5.3 shipped here.

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

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

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

COMMON ITEMS:

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

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

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

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

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

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

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

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

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

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

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


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

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


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

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

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

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

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

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

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

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

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

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

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

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

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

Copyright information:

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

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

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