freebsd kernel with SKQ
07cfd3813e
memory with 4MB pages was added to pmap_object_init_pt(). This code assumes that the pages of a OBJT_DEVICE object are always physically contiguous. Unfortunately, this is not always the case. For example, jhb@ informs me that the recently introduced /dev/ksyms driver creates a OBJT_DEVICE object that violates this assumption. Thus, this revision modifies pmap_object_init_pt() to abort the mapping if the OBJT_DEVICE object's pages are not physically contiguous. This revision also changes some inconsistent if not buggy behavior. For example, the i386 version aborts if the first 4MB virtual page that would be mapped is already valid. However, it incorrectly replaces any subsequent 4MB virtual page mappings that it encounters, potentially leaking a page table page. The amd64 version has a bug of my own creation. It potentially busies the wrong page and always an insufficent number of pages if it blocks allocating a page table page. To my knowledge, there have been no reports of these bugs, hence, their persistance. I suspect that the existing restrictions that pmap_object_init_pt() placed on the OBJT_DEVICE objects that it would choose to map, for example, that the first page must be aligned on a 2 or 4MB physical boundary and that the size of the mapping must be a multiple of the large page size, were enough to avoid triggering the bug for drivers like ksyms. However, one side effect of testing the OBJT_DEVICE object's pages for physical contiguity is that a dubious difference between pmap_object_init_pt() and the standard path for mapping devices pages, i.e., vm_fault(), has been eliminated. Previously, pmap_object_init_pt() would only instantiate the first PG_FICTITOUS page being mapped because it never examined the rest. Now, however, pmap_object_init_pt() uses the new function vm_object_populate() to instantiate them all (in order to support testing their physical contiguity). These pages need to be instantiated for the mechanism that I have prototyped for automatically maintaining the consistency of the PAT settings across multiple mappings, particularly, amd64's direct mapping, to work. (Translation: This change is also being made to support jhb@'s work on the Nvidia feature requests.) Discussed with: jhb@ |
||
|---|---|---|
| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| ObsoleteFiles.inc | ||
| README | ||
| UPDATING | ||
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