c19547f379
The remaining, unmerged portions of r175404 Retire PMAP_DIAGNOSTIC. Any useful diagnostics that were conditionally compiled under PMAP_DIAGNOSTIC are now KASSERT()s. (Note: The kernel option DIAGNOSTIC still disables inlining of certain pmap functions.) Eliminate dead code from pmap_enter(). This code implemented an assertion. On i386, an equivalent check is already implemented. However, on amd64, a small change is required to implement an equivalent check. Eliminate \n from a nearby panic string. Use KASSERT() to reimplement pmap_copy()'s two assertions. Merge portions of r177659 To date, we have assumed that the TLB will only set the PG_M bit in a PTE if that PTE has the PG_RW bit set. However, this assumption does not hold on recent processors from Intel. For example, consider a PTE that has the PG_RW bit set but the PG_M bit clear. Suppose this PTE is cached in the TLB and later the PG_RW bit is cleared in the PTE, but the corresponding TLB entry is not (yet) invalidated. Historically, upon a write access using this (stale) TLB entry, the TLB would observe that the PG_RW bit had been cleared and initiate a page fault, aborting the setting of the PG_M bit in the PTE. Now, however, P4- and Core2-family processors will set the PG_M bit before observing that the PG_RW bit is clear and initiating a page fault. In other words, the write does not occur but the PG_M bit is still set. The real impact of this difference is not that great. Specifically, we should no longer assert that any PTE with the PG_M bit set must also have the PG_RW bit set, and we should ignore the state of the PG_M bit unless the PG_RW bit is set. r208609 Defer freeing any page table pages in pmap_remove_all() until after the page queues lock is released. This may reduce the amount of time that the page queues lock is held by pmap_remove_all(). r208645 When I pushed down the page queues lock into pmap_is_modified(), I created an ordering dependence: A pmap operation that clears PG_WRITEABLE and calls vm_page_dirty() must perform the call first. Otherwise, pmap_is_modified() could return FALSE without acquiring the page queues lock because the page is not (currently) writeable, and the caller to pmap_is_modified() might believe that the page's dirty field is clear because it has not seen the effect of the vm_page_dirty() call. When I pushed down the page queues lock into pmap_is_modified(), I overlooked one place where this ordering dependence is violated: pmap_enter(). In a rare situation pmap_enter() can be called to replace a dirty mapping to one page with a mapping to another page. (I say rare because replacements generally occur as a result of a copy-on-write fault, and so the old page is not dirty.) This change delays clearing PG_WRITEABLE until after vm_page_dirty() has been called. Fixing the ordering dependency also makes it easy to introduce a small optimization: When pmap_enter() used to replace a mapping to one page with a mapping to another page, it freed the pv entry for the first mapping and later called the pv entry allocator for the new mapping. Now, pmap_enter() attempts to recycle the old pv entry, saving two calls to the pv entry allocator. There is no point in setting PG_WRITEABLE on unmanaged pages, so don't. Update a comment to reflect this. Tidy up the variable declarations at the start of pmap_enter().
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. 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