Commit Graph

402 Commits

Author SHA1 Message Date
Richard Scheffenegger
4d0770f172 Prevent premature SACK block transmission during loss recovery
Under specific conditions, a window update can be sent with
outdated SACK information. Some clients react to this by
subsequently delaying loss recovery, making TCP perform very
poorly.

Reported by:	chengc_netapp.com
Reviewed by:	rrs, jtl
MFC after:	2 weeks
Sponsored by:	NetApp, Inc.
Differential Revision:	https://reviews.freebsd.org/D24237
2020-11-08 18:47:05 +00:00
Mateusz Guzik
662c13053f net: clean up empty lines in .c and .h files 2020-09-01 21:19:14 +00:00
Pawel Biernacki
7029da5c36 Mark more nodes as CTLFLAG_MPSAFE or CTLFLAG_NEEDGIANT (17 of many)
r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly marked).
Use it in preparation for a general review of all nodes.

This is non-functional change that adds annotations to SYSCTL_NODE and
SYSCTL_PROC nodes using one of the soon-to-be-required flags.

Mark all obvious cases as MPSAFE.  All entries that haven't been marked
as MPSAFE before are by default marked as NEEDGIANT

Approved by:	kib (mentor, blanket)
Commented by:	kib, gallatin, melifaro
Differential Revision:	https://reviews.freebsd.org/D23718
2020-02-26 14:26:36 +00:00
Randall Stewart
481be5de9d White space cleanup -- remove trailing tab's or spaces
from any line.

Sponsored by:	Netflix Inc.
2020-02-12 13:31:36 +00:00
Michael Tuexen
a1f0e13475 This patch addresses an issue brought up by bz@ in D18968:
When TCP_REASS_LOGGING is defined, a NULL pointer dereference would happen,
if user data was received during the TCP handshake and BB logging is used.

A KASSERT is also added to detect tcp_reass() calls with illegal parameter
combinations.

Reported by:		bz@
Reviewed by:		rrs@
MFC after:		3 days
Sponsored by:		Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D19254
2019-02-21 09:34:47 +00:00
Michael Tuexen
f635b1c264 Don't include two header files when not needed.
This allows the part of the rewrite of TCP reassembly in this
files to be MFCed to stable/11 with manual change.

MFC after:		3 days
Sponsored by:		Netflix, Inc.
2019-01-25 17:08:28 +00:00
Michael Tuexen
09423f72fd Fix a regression in the TCP handling of received segments.
When receiving TCP segments the stack protects itself by limiting
the resources allocated for a TCP connections. This patch adds
an exception to these limitations for the TCP segement which is the next
expected in-sequence segment. Without this patch, TCP connections
may stall and finally fail in some cases of packet loss.

Reported by:		jhb@
Reviewed by:		jtl@, rrs@
MFC after:		3 days
Sponsored by:		Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D18580
2018-12-20 16:05:30 +00:00
Jonathan T. Looney
ac75e35d85 In r338102, the TCP reassembly code was substantially restructured. Prior
to this change, the code sometimes used a temporary stack variable to hold
details of a TCP segment. r338102 stopped using the variable to hold
segments, but did not actually remove the variable.

Because the variable is no longer used, we can safely remove it.

Approved by:	re (gjb)
2018-10-16 14:41:09 +00:00
Randall Stewart
c28440db29 This change represents a substantial restructure of the way we
reassembly inbound tcp segments. The old algorithm just blindly
dropped in segments without coalescing. This meant that every
segment could take up greater and greater room on the linked list
of segments. This of course is now subject to a tighter limit (100)
of segments which in a high BDP situation will cause us to be a
lot more in-efficent as we drop segments beyond 100 entries that
we receive. What this restructure does is cause the reassembly
buffer to coalesce segments putting an emphasis on the two
common cases (which avoid walking the list of segments) i.e.
where we add to the back of the queue of segments and where we
add to the front. We also have the reassembly buffer supporting
a couple of debug options (black box logging as well as counters
for code coverage). These are compiled out by default but can
be added by uncommenting the defines.

Sponsored by:	Netflix Inc.
Differential Revision:	https://reviews.freebsd.org/D16626
2018-08-20 12:43:18 +00:00
Jonathan T. Looney
95a914f631 Address concerns about CPU usage while doing TCP reassembly.
Currently, the per-queue limit is a function of the receive buffer
size and the MSS.  In certain cases (such as connections with large
receive buffers), the per-queue segment limit can be quite large.
Because we process segments as a linked list, large queues may not
perform acceptably.

The better long-term solution is to make the queue more efficient.
But, in the short-term, we can provide a way for a system
administrator to set the maximum queue size.

We set the default queue limit to 100.  This is an effort to balance
performance with a sane resource limit.  Depending on their
environment, goals, etc., an administrator may choose to modify this
limit in either direction.

Reviewed by:	jhb
Approved by:	so
Security:	FreeBSD-SA-18:08.tcp
Security:	CVE-2018-6922
2018-08-06 17:36:57 +00:00
Pedro F. Giffuni
51369649b0 sys: further adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
2017-11-20 19:43:44 +00:00
Gleb Smirnoff
7637c57ee1 There is no good reason for TCP reassembly zone to be UMA_ZONE_NOFREE.
It has strong locking model, doesn't have any timers associated with
entries.  The entries theirselves are referenced only from the tcpcb zone,
which itself is a normal zone, without the UMA_ZONE_NOFREE flag.
2017-05-10 23:32:31 +00:00
Warner Losh
fbbd9655e5 Renumber copyright clause 4
Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by:	Jan Schaumann <jschauma@stevens.edu>
Pull Request:	https://github.com/freebsd/freebsd/pull/96
2017-02-28 23:42:47 +00:00
Alexander V. Chernikov
ea8d14925c Remove sys/eventhandler.h from net/route.h
Reviewed by:	ae
2016-01-09 09:34:39 +00:00
Alexander V. Chernikov
1558cb2448 Eliminate nd6_nud_hint() and its TCP bindings.
Initially function was introduced in r53541 (KAME initial commit) to
  "provide hints from upper layer protocols that indicate a connection
  is making "forward progress"" (quote from RFC 2461 7.3.1 Reachability
  Confirmation).
However, it was converted to do nothing (e.g. just return) in r122922
  (tcp_hostcache implementation) back in 2003. Some defines were moved
  to tcp_var.h in r169541. Then, it was broken (for non-corner cases)
  by r186119 (L2<>L3 split) in 2008 (NULL ifp in nd6_lookup). So,
  right now this code is broken and has no "real" base users.

Differential Revision:	https://reviews.freebsd.org/D3699
2015-09-27 05:29:34 +00:00
Kristof Provost
30edc5385e tcp_reass_zone is not a VNET variable.
This fixes a panic during 'sysctl -a' on VIMAGE kernels.

The tcp_reass_zone variable is not VNET_DEFINE() so we can not mark it as a VNET
variable (with CTLFLAG_VNET).
2015-08-09 19:07:24 +00:00
Patrick Kelsey
4741bfcb57 Revert r265338, r271089 and r271123 as those changes do not handle
non-inline urgent data and introduce an mbuf exhaustion attack vector
similar to FreeBSD-SA-15:15.tcp, but not requiring VNETs.

Address the issue described in FreeBSD-SA-15:15.tcp.

Reviewed by:	glebius
Approved by:	so
Approved by:	jmallett (mentor)
Security:	FreeBSD-SA-15:15.tcp
Sponsored by:	Norse Corp, Inc.
2015-07-29 17:59:13 +00:00
Gleb Smirnoff
651e4e6a30 Merge from projects/sendfile: extend protocols API to support
sending not ready data:
o Add new flag to pru_send() flags - PRUS_NOTREADY.
o Add new protocol method pru_ready().

Sponsored by:	Nginx, Inc.
Sponsored by:	Netflix
2014-11-30 13:24:21 +00:00
Gleb Smirnoff
770aa6cb25 Satisfy assertion in m_demote().
Sponsored by:	Nginx, Inc.
2014-09-04 19:28:02 +00:00
Gleb Smirnoff
ba32fcfff9 Improve r265338. When inserting mbufs into TCP reassembly queue,
try to collapse adjacent pieces using m_catpkt(). In best case
scenario it copies data and frees mbufs, making mbuf exhaustion
attack harder.

Suggested by:		Jonathan Looney <jonlooney gmail.com>
Security:		Hardens against remote mbuf exhaustion attack.
Sponsored by:		Netflix
Sponsored by:		Nginx, Inc.
2014-09-04 09:15:44 +00:00
Gleb Smirnoff
c669105d17 - Remove net.inet.tcp.reass.overflows sysctl. It counts exactly
same events that tcpstat's tcps_rcvmemdrop counter counts.
- Rename tcps_rcvmemdrop to tcps_rcvreassfull and improve its
  description in netstat(1) output.

Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.
2014-05-06 00:00:07 +00:00
Gleb Smirnoff
6c42c8a93f The tcp_log_addrs() uses th pointer, which points into the mbuf, thus we
can not free the mbuf before tcp_log_addrs().

Sponsored by:	Nginx, Inc.
Sponsored by:	Netflix
2014-05-05 21:33:20 +00:00
Gleb Smirnoff
e407b67be4 The FreeBSD-SA-14:08.tcp was a lesson on not doing acrobatics with
mixing on stack memory and UMA memory in one linked list.

Thus, rewrite TCP reassembly code in terms of memory usage. The
algorithm remains unchanged.

We actually do not need extra memory to build a reassembly queue.
Arriving mbufs are always packet header mbufs. So we got the length
of data as pkthdr.len. We got m_nextpkt for linkage. And we need
only one pointer to point at the tcphdr, use PH_loc for that.

In tcpcb the t_segq fields becomes mbuf pointer. The t_segqlen
field now counts not packets, but bytes in the queue. This gives
us more precision when comparing to socket buffer limits.

Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.
2014-05-04 23:25:32 +00:00
Xin LI
c6f70658c3 Fix TCP reassembly vulnerability.
Patch done by:	glebius
Security:	FreeBSD-SA-14:08.tcp
Security:	CVE-2014-3000
2014-04-30 04:02:57 +00:00
Gleb Smirnoff
92f8975ff4 Utilize SYSCTL_UMA_CUR() to export usage of syncache and
tcp reassembly zones.

Sponsored by:	Nginx, Inc.
2014-02-07 14:31:51 +00:00
Gleb Smirnoff
76039bc84f The r48589 promised to remove implicit inclusion of if_var.h soon. Prepare
to this event, adding if_var.h to files that do need it. Also, include
all includes that now are included due to implicit pollution via if_var.h

Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.
2013-10-26 17:58:36 +00:00
Andre Oppermann
cda3447bb0 uma_zone_set_max() directly returns the rounded effective zone
limit.  Use the return value directly instead of doing a second
uma_zone_set_max() step.

MFC after:	1 week
2013-02-01 14:21:09 +00:00
Gleb Smirnoff
e8db9937f3 Fix sysctl_handle_int() usage. Either arg1 or arg2 should be supplied,
and arg2 doesn't pass size of arg1.
2012-12-25 13:55:21 +00:00
Andre Oppermann
aafa0b4164 Simplify implementation of net.inet.tcp.reass.maxsegments and
net.inet.tcp.reass.cursegments.

MFC after:	2 weeks
2012-10-28 17:59:46 +00:00
Lawrence Stewart
a26fef3a21 Plug a TCP reassembly UMA zone leak introduced in r226113 by only using the
backup stack queue entry when the zone is exhausted, otherwise we leak a zone
allocation each time we plug a hole in the reassembly queue.

Reported by:	many on freebsd-stable@ (thread: "TCP Reassembly Issues")
Tested by:	many on freebsd-stable@ (thread: "TCP Reassembly Issues")
Reviewed by:	bz (very brief sanity check)
MFC after:	3 days
2011-11-27 02:32:08 +00:00
Ed Schouten
6472ac3d8a Mark all SYSCTL_NODEs static that have no corresponding SYSCTL_DECLs.
The SYSCTL_NODE macro defines a list that stores all child-elements of
that node. If there's no SYSCTL_DECL macro anywhere else, there's no
reason why it shouldn't be static.
2011-11-07 15:43:11 +00:00
Andre Oppermann
1593dcd025 Prevent TCP sessions from stalling indefinitely in reassembly
when reaching the zone limit of reassembly queue entries.

When the zone limit was reached not even the missing segment
that would complete the sequence space could be processed
preventing the TCP session forever from making any further
progress.

Solve this deadlock by using a temporary on-stack queue entry
for the missing segment followed by an immediate dequeue again
by delivering the contiguous sequence space to the socket.

Add logging under net.inet.tcp.log_debug for reassembly queue
issues.

Reviewed by:	lsteward (previous version)
Tested by: 	Steven Hartland <killing-at-multiplay.co.uk>
MFC after:	3 days
2011-10-07 16:39:03 +00:00
Matthew D Fleming
79c3d51b86 Specify a CTLTYPE_FOO so that a future sysctl(8) change does not need
to rely on the format string.  For SYSCTL_PROC instances that I
noticed a discrepancy between the CTLTYPE and the format specifier,
fix the CTLTYPE.
2011-01-18 21:14:13 +00:00
John Baldwin
79e955ed63 Trim extra spaces before tabs. 2011-01-07 21:40:34 +00:00
Dimitry Andric
3e288e6238 After some off-list discussion, revert a number of changes to the
DPCPU_DEFINE and VNET_DEFINE macros, as these cause problems for various
people working on the affected files.  A better long-term solution is
still being considered.  This reversal may give some modules empty
set_pcpu or set_vnet sections, but these are harmless.

Changes reverted:

------------------------------------------------------------------------
r215318 | dim | 2010-11-14 21:40:55 +0100 (Sun, 14 Nov 2010) | 4 lines

Instead of unconditionally emitting .globl's for the __start_set_xxx and
__stop_set_xxx symbols, only emit them when the set_vnet or set_pcpu
sections are actually defined.

------------------------------------------------------------------------
r215317 | dim | 2010-11-14 21:38:11 +0100 (Sun, 14 Nov 2010) | 3 lines

Apply the STATIC_VNET_DEFINE and STATIC_DPCPU_DEFINE macros throughout
the tree.

------------------------------------------------------------------------
r215316 | dim | 2010-11-14 21:23:02 +0100 (Sun, 14 Nov 2010) | 2 lines

Add macros to define static instances of VNET_DEFINE and DPCPU_DEFINE.
2010-11-22 19:32:54 +00:00
George V. Neville-Neil
f5d34df525 Add new, per connection, statistics for TCP, including:
Retransmitted Packets
Zero Window Advertisements
Out of Order Receives

These statistics are available via the -T argument to
netstat(1).
MFC after:	2 weeks
2010-11-17 18:55:12 +00:00
Dimitry Andric
31c6a0037e Apply the STATIC_VNET_DEFINE and STATIC_DPCPU_DEFINE macros throughout
the tree.
2010-11-14 20:38:11 +00:00
Lawrence Stewart
ca09d7728b Retire the system-wide, per-reassembly queue segment limit. The mechanism is far
too coarse grained to be useful and the default value significantly degrades TCP
performance on moderate to high bandwidth-delay product paths with non-zero loss
(e.g. 5+Mbps connections across the public Internet often suffer).

Replace the outgoing mechanism with an individual per-queue limit based on the
number of MSS segments that fit into the socket's receive buffer. This should
strike a good balance between performance and the potential for resource
exhaustion when FreeBSD is acting as a TCP receiver. With socket buffer
autotuning (which is enabled by default), the reassembly queue tracks the
socket buffer and benefits too.

As the XXX comment suggests, my testing uncovered some unexpected behaviour
which requires further investigation. By using so->so_rcv.sb_hiwat
instead of sbspace(&so->so_rcv), we allow more segments to be held across both
the socket receive buffer and reassembly queue than we probably should. The
tradeoff is better performance in at least one common scenario, versus a devious
sender's ability to consume more resources on a FreeBSD receiver.

Sponsored by:	FreeBSD Foundation
Reviewed by:	andre, gnn, rpaulo
MFC after:	2 weeks
2010-10-16 07:12:39 +00:00
Lawrence Stewart
c8dc0ab886 - Switch the "net.inet.tcp.reass.cursegments" and
"net.inet.tcp.reass.maxsegments" sysctl variables to be based on UMA zone
  stats. The value returned by the cursegments sysctl is approximate owing to
  the way in which uma_zone_get_cur is implemented.

- Discontinue use of V_tcp_reass_qsize as a global reassembly segment count
  variable in the reassembly implementation. The variable was used without
  proper synchronisation and was duplicating accounting done by UMA already. The
  lack of synchronisation was particularly problematic on SMP systems
  terminating many TCP sessions, resulting in poor TCP performance for
  connections with non-zero packet loss.

Sponsored by:	FreeBSD Foundation
Reviewed by:	andre, gnn, rpaulo (as part of a larger patch)
MFC after:	2 weeks
2010-10-16 05:37:45 +00:00
Lawrence Stewart
0c236c4ebd Internalise reassembly queue related functionality and variables which should
not be used outside of the reassembly queue implementation. Provide a new
function to flush all segments from a reassembly queue and call it from the
appropriate places instead of manipulating the queue directly.

Sponsored by:	FreeBSD Foundation
Reviewed by:	andre, gnn, rpaulo
MFC after:	2 weeks
2010-09-25 04:58:46 +00:00
Bjoern A. Zeeb
82cea7e6f3 MFP4: @176978-176982, 176984, 176990-176994, 177441
"Whitspace" churn after the VIMAGE/VNET whirls.

Remove the need for some "init" functions within the network
stack, like pim6_init(), icmp_init() or significantly shorten
others like ip6_init() and nd6_init(), using static initialization
again where possible and formerly missed.

Move (most) variables back to the place they used to be before the
container structs and VIMAGE_GLOABLS (before r185088) and try to
reduce the diff to stable/7 and earlier as good as possible,
to help out-of-tree consumers to update from 6.x or 7.x to 8 or 9.

This also removes some header file pollution for putatively
static global variables.

Revert VIMAGE specific changes in ipfilter::ip_auth.c, that are
no longer needed.

Reviewed by:	jhb
Discussed with:	rwatson
Sponsored by:	The FreeBSD Foundation
Sponsored by:	CK Software GmbH
MFC after:	6 days
2010-04-29 11:52:42 +00:00
Bjoern A. Zeeb
376aadf896 Destroy TCP UMA zones (empty or not) upon network stack teardown
to not leak them, otherwise making UMA/vmstat unhappy with every stoped vnet.
We will still leak pages (especially for zones marked NOFREE).

Reshuffle cleanup order in tcp_destroy() to get rid of what we can
easily free first.

Sponsored by:	ISPsystem
Reviewed by:	rwatson
MFC after:	5 days
2010-03-07 15:58:44 +00:00
Robert Watson
530c006014 Merge the remainder of kern_vimage.c and vimage.h into vnet.c and
vnet.h, we now use jails (rather than vimages) as the abstraction
for virtualization management, and what remained was specific to
virtual network stacks.  Minor cleanups are done in the process,
and comments updated to reflect these changes.

Reviewed by:	bz
Approved by:	re (vimage blanket)
2009-08-01 19:26:27 +00:00
Robert Watson
1e77c1056a Remove unused VNET_SET() and related macros; only VNET_GET() is
ever actually used.  Rename VNET_GET() to VNET() to shorten
variable references.

Discussed with:	bz, julian
Reviewed by:	bz
Approved by:	re (kensmith, kib)
2009-07-16 21:13:04 +00:00
Robert Watson
eddfbb763d Build on Jeff Roberson's linker-set based dynamic per-CPU allocator
(DPCPU), as suggested by Peter Wemm, and implement a new per-virtual
network stack memory allocator.  Modify vnet to use the allocator
instead of monolithic global container structures (vinet, ...).  This
change solves many binary compatibility problems associated with
VIMAGE, and restores ELF symbols for virtualized global variables.

Each virtualized global variable exists as a "reference copy", and also
once per virtual network stack.  Virtualized global variables are
tagged at compile-time, placing the in a special linker set, which is
loaded into a contiguous region of kernel memory.  Virtualized global
variables in the base kernel are linked as normal, but those in modules
are copied and relocated to a reserved portion of the kernel's vnet
region with the help of a the kernel linker.

Virtualized global variables exist in per-vnet memory set up when the
network stack instance is created, and are initialized statically from
the reference copy.  Run-time access occurs via an accessor macro, which
converts from the current vnet and requested symbol to a per-vnet
address.  When "options VIMAGE" is not compiled into the kernel, normal
global ELF symbols will be used instead and indirection is avoided.

This change restores static initialization for network stack global
variables, restores support for non-global symbols and types, eliminates
the need for many subsystem constructors, eliminates large per-subsystem
structures that caused many binary compatibility issues both for
monitoring applications (netstat) and kernel modules, removes the
per-function INIT_VNET_*() macros throughout the stack, eliminates the
need for vnet_symmap ksym(2) munging, and eliminates duplicate
definitions of virtualized globals under VIMAGE_GLOBALS.

Bump __FreeBSD_version and update UPDATING.

Portions submitted by:  bz
Reviewed by:            bz, zec
Discussed with:         gnn, jamie, jeff, jhb, julian, sam
Suggested by:           peter
Approved by:            re (kensmith)
2009-07-14 22:48:30 +00:00
Robert Watson
cce6e15556 Remove comment about moving tcp_reass() to its own file named tcp_reass.c,
that happened a while ago.

MFC after:	3 days
2009-05-25 14:51:47 +00:00
Robert Watson
78b5071407 Update stats in struct tcpstat using two new macros, TCPSTAT_ADD() and
TCPSTAT_INC(), rather than directly manipulating the fields across the
kernel.  This will make it easier to change the implementation of
these statistics, such as using per-CPU versions of the data structures.

MFC after:	3 days
2009-04-11 22:07:19 +00:00
Marko Zec
1ed81b739e First pass at separating per-vnet initializer functions
from existing functions for initializing global state.

        At this stage, the new per-vnet initializer functions are
	directly called from the existing global initialization code,
	which should in most cases result in compiler inlining those
	new functions, hence yielding a near-zero functional change.

        Modify the existing initializer functions which are invoked via
        protosw, like ip_init() et. al., to allow them to be invoked
	multiple times, i.e. per each vnet.  Global state, if any,
	is initialized only if such functions are called within the
	context of vnet0, which will be determined via the
	IS_DEFAULT_VNET(curvnet) check (currently always true).

        While here, V_irtualize a few remaining global UMA zones
        used by net/netinet/netipsec networking code.  While it is
        not yet clear to me or anybody else whether this is the right
        thing to do, at this stage this makes the code more readable,
        and makes it easier to track uncollected UMA-zone-backed
        objects on vnet removal.  In the long run, it's quite possible
        that some form of shared use of UMA zone pools among multiple
        vnets should be considered.

	Bump __FreeBSD_version due to changes in layout of structs
	vnet_ipfw, vnet_inet and vnet_net.

Approved by:	julian (mentor)
2009-04-06 22:29:41 +00:00
Bjoern A. Zeeb
4b79449e2f Rather than using hidden includes (with cicular dependencies),
directly include only the header files needed. This reduces the
unneeded spamming of various headers into lots of files.

For now, this leaves us with very few modules including vnet.h
and thus needing to depend on opt_route.h.

Reviewed by:	brooks, gnn, des, zec, imp
Sponsored by:	The FreeBSD Foundation
2008-12-02 21:37:28 +00:00
Marko Zec
44e33a0758 Change the initialization methodology for global variables scheduled
for virtualization.

Instead of initializing the affected global variables at instatiation,
assign initial values to them in initializer functions.  As a rule,
initialization at instatiation for such variables should never be
introduced again from now on.  Furthermore, enclose all instantiations
of such global variables in #ifdef VIMAGE_GLOBALS blocks.

Essentialy, this change should have zero functional impact.  In the next
phase of merging network stack virtualization infrastructure from
p4/vimage branch, the new initialization methology will allow us to
switch between using global variables and their counterparts residing in
virtualization containers with minimum code churn, and in the long run
allow us to intialize multiple instances of such container structures.

Discussed at:	devsummit Strassburg
Reviewed by:	bz, julian
Approved by:	julian (mentor)
Obtained from:	//depot/projects/vimage-commit2/...
X-MFC after:	never
Sponsored by:	NLnet Foundation, The FreeBSD Foundation
2008-11-19 09:39:34 +00:00