freebsd kernel with SKQ
d87d5bbf82
side-effect of purging more than the requested translation. While this is not a problem in general, it invalidates the assumption made during constructing the trapframe on entry into the kernel in SMP configurations. The assumption is that only the first store to the stack will possibly cause a TLB miss. Since the ptc.g purges the translation caches of all CPUs in the coherency domain, a ptc.g executed on one CPU can cause a purge on another CPU that is currently running the critical code that saves the state to the trapframe. This can cause an unexpected TLB miss and with interrupt collection disabled this means an unexpected data nested TLB fault. A data nested TLB fault will not save any context, nor provide a way for software to determine what caused the TLB miss nor where it occured. Careful construction of the kernel entry and exit code allows us to handle a TLB miss in precisely orchastrated points and thereby avoiding the need to wire the kernel stack, but the unexpected TLB miss caused by the ptc.g instructution resulted in an unrecoverable condition and resulting in machine checks. The solution to this problem is to synchronize the kernel entry on all CPUs with the use of the ptc.g instruction on a single CPU by implementing a bare-bones readers-writer lock that allows N readers (= N CPUs entering the kernel) and 1 writer (= execution of the ptc.g instruction on some CPU). This solution wins over a rendez-vous approach by not interrupting CPUs with an IPI. This problem has not been observed on the Montecito. PR: ia64/147772 MFC after: 6 days |
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| 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