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Alan Cox 5730afc9b6 Handle spurious page faults that may occur in no-fault sections of the
kernel.

When access restrictions are added to a page table entry, we flush the
corresponding virtual address mapping from the TLB.  In contrast, when
access restrictions are removed from a page table entry, we do not
flush the virtual address mapping from the TLB.  This is exactly as
recommended in AMD's documentation.  In effect, when access
restrictions are removed from a page table entry, AMD's MMUs will
transparently refresh a stale TLB entry.  In short, this saves us from
having to perform potentially costly TLB flushes.  In contrast,
Intel's MMUs are allowed to generate a spurious page fault based upon
the stale TLB entry.  Usually, such spurious page faults are handled
by vm_fault() without incident.  However, when we are executing
no-fault sections of the kernel, we are not allowed to execute
vm_fault().  This change introduces special-case handling for spurious
page faults that occur in no-fault sections of the kernel.

In collaboration with:	kib
Tested by:		gibbs (an earlier version)

I would also like to acknowledge Hiroki Sato's assistance in
diagnosing this problem.

MFC after:	1 week
2012-03-22 04:52:51 +00:00
bin rm[0].rm_so must be zero (an explicit check is made for zero in the 2012-03-19 00:45:01 +00:00
cddl Analogous to r232059, add a parameter for the ZFS file system: 2012-02-26 16:30:39 +00:00
contrib Import new version of libcxxrt. Now works correctly with libobjc2 to implement 2012-03-20 17:58:15 +00:00
crypto Polish diff against upstream. 2012-02-13 11:59:59 +00:00
etc Rotate auth.log and messages at the beginning of a year. Otherwise, 2012-03-19 09:30:40 +00:00
games o Preserve argv[0] to use it later in usage(). 2012-01-28 15:29:43 +00:00
gnu Note two shortcomings of GDB on MIPS that should be addressed. 2012-03-13 04:50:41 +00:00
include Expose some C11 stuff that is also C++11 stuff in C++11 mode. 2012-03-14 14:39:07 +00:00
kerberos5 Don't support OpenLDAP during lib32 build. 2011-12-06 12:03:01 +00:00
lib Revert previous change. It is an incomplete change from old branch. :-( 2012-03-21 07:16:58 +00:00
libexec Fix several problems with our ELF filters implementation. 2012-03-20 13:20:49 +00:00
release Make sure not to tar up CVS directories if this ports tree is a CVS 2012-03-09 02:23:03 +00:00
rescue Disable jail support in ifconfig when either building a rescue 2012-02-14 07:14:42 +00:00
sbin Document GEOM_PART_LDM scheme and partition types. 2012-03-19 13:17:47 +00:00
secure X11BASE is not used any more and has been killed by the x11 team. 2012-03-19 00:41:40 +00:00
share Merge ACPICA 20120320. 2012-03-20 21:37:52 +00:00
sys Handle spurious page faults that may occur in no-fault sections of the 2012-03-22 04:52:51 +00:00
tools Use new -n option when executing kldload, to 2012-03-18 09:47:27 +00:00
usr.bin Add multibyte char support. 2012-03-21 08:03:07 +00:00
usr.sbin Fix a sentence in a paragraph that describes time and interval based 2012-03-21 07:02:17 +00:00
COPYRIGHT Happy 2012 to FreeBSD users in Samoa. 2011-12-31 04:38:04 +00:00
LOCKS
MAINTAINERS Add isci(4) driver for amd64 and i386 targets. 2012-01-31 19:38:18 +00:00
Makefile Add a kernel-toolchains target like the toolchains target, but building only 2012-03-13 00:38:49 +00:00
Makefile.inc1 Make sure libgcc_s is finished building in _startup_libs before 2012-03-17 22:12:09 +00:00
ObsoleteFiles.inc Remove TARGET_ARCH conditionals for COMPAT_FREEBSD32. 2012-03-15 17:01:25 +00:00
README
UPDATING Disable the option VFS_ALLOW_NONMPSAFE by default on all the supported 2012-03-06 20:01:25 +00:00

This is the top level of the FreeBSD source directory.  This file
was last revised on:
$FreeBSD$

For copyright information, please see the file COPYRIGHT in this
directory (additional copyright information also exists for some
sources in this tree - please see the specific source directories for
more information).

The Makefile in this directory supports a number of targets for
building components (or all) of the FreeBSD source tree, the most
commonly used one being ``world'', which rebuilds and installs
everything in the FreeBSD system from the source tree except the
kernel, the kernel-modules and the contents of /etc.  The ``world''
target should only be used in cases where the source tree has not
changed from the currently running version.  See:
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html
for more information, including setting make(1) variables.

The ``buildkernel'' and ``installkernel'' targets build and install
the kernel and the modules (see below).  Please see the top of
the Makefile in this directory for more information on the
standard build targets and compile-time flags.

Building a kernel is a somewhat more involved process, documentation
for which can be found at:
   http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html
And in the config(8) man page.
Note: If you want to build and install the kernel with the
``buildkernel'' and ``installkernel'' targets, you might need to build
world before.  More information is available in the handbook.

The sample kernel configuration files reside in the sys/<arch>/conf
sub-directory (assuming that you've installed the kernel sources), the
file named GENERIC being the one used to build your initial installation
kernel.  The file NOTES contains entries and documentation for all possible
devices, not just those commonly used.  It is the successor of the ancient
LINT file, but in contrast to LINT, it is not buildable as a kernel but a
pure reference and documentation file.


Source Roadmap:
---------------
bin		System/user commands.

cddl		Various commands and libraries under the Common Development
		and Distribution License.

contrib		Packages contributed by 3rd parties.

crypto		Cryptography stuff (see crypto/README).

etc		Template files for /etc.

games		Amusements.

gnu		Various commands and libraries under the GNU Public License.
		Please see gnu/COPYING* for more information.

include		System include files.

kerberos5	Kerberos5 (Heimdal) package.

lib		System libraries.

libexec		System daemons.

release		Release building Makefile & associated tools.

rescue		Build system for statically linked /rescue utilities.

sbin		System commands.

secure		Cryptographic libraries and commands.

share		Shared resources.

sys		Kernel sources.

tools		Utilities for regression testing and miscellaneous tasks.

usr.bin		User commands.

usr.sbin	System administration commands.


For information on synchronizing your source tree with one or more of
the FreeBSD Project's development branches, please see:

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