From 9242c645f81d22058934688725f1fff0bc88cb64 Mon Sep 17 00:00:00 2001 From: uqs Date: Sat, 4 Dec 2010 10:11:20 +0000 Subject: Move most of the remaining USD/PSD/SMM papers into share/doc --- share/doc/smm/02.config/b.t | 137 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 137 insertions(+) create mode 100644 share/doc/smm/02.config/b.t (limited to 'share/doc/smm/02.config/b.t') diff --git a/share/doc/smm/02.config/b.t b/share/doc/smm/02.config/b.t new file mode 100644 index 0000000..901a009 --- /dev/null +++ b/share/doc/smm/02.config/b.t @@ -0,0 +1,137 @@ +.\" Copyright (c) 1983, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)b.t 8.1 (Berkeley) 6/8/93 +.\" +.\".ds RH "Device Defaulting Rules +.bp +.LG +.B +.ce +APPENDIX B. RULES FOR DEFAULTING SYSTEM DEVICES +.sp +.R +.NL +.PP +When \fIconfig\fP processes a ``config'' rule which does +not fully specify the location of the root file system, +paging area(s), device for system dumps, and device for +argument list processing it applies a set of rules to +define those values left unspecified. The following list +of rules are used in defaulting system devices. +.IP 1) 3 +If a root device is not specified, the swap +specification must indicate a ``generic'' system is to be built. +.IP 2) 3 +If the root device does not specify a unit number, it +defaults to unit 0. +.IP 3) 3 +If the root device does not include a partition specification, +it defaults to the ``a'' partition. +.IP 4) 3 +If no swap area is specified, it defaults to the ``b'' +partition of the root device. +.IP 5) 3 +If no device is specified for processing argument lists, the +first swap partition is selected. +.IP 6) 3 +If no device is chosen for system dumps, the first swap +partition is selected (see below to find out where dumps are +placed within the partition). +.PP +The following table summarizes the default partitions selected +when a device specification is incomplete, e.g. ``hp0''. +.DS +.TS +l l. +Type Partition +_ +root ``a'' +swap ``b'' +args ``b'' +dumps ``b'' +.TE +.DE +.SH +Multiple swap/paging areas +.PP +When multiple swap partitions are specified, the system treats the +first specified as a ``primary'' swap area which is always used. +The remaining partitions are then interleaved into the paging +system at the time a +.IR swapon (2) +system call is made. This is normally done at boot time with +a call to +.IR swapon (8) +from the /etc/rc file. +.SH +System dumps +.PP +System dumps are automatically taken after a system crash, +provided the device driver for the ``dumps'' device supports +this. The dump contains the contents of memory, but not +the swap areas. Normally the dump device is a disk in +which case the information is copied to a location at the +back of the partition. The dump is placed in the back of the +partition because the primary swap and dump device are commonly +the same device and this allows the system to be rebooted without +immediately overwriting the saved information. When a dump has +occurred, the system variable \fIdumpsize\fP +is set to a non-zero value indicating the size (in bytes) of +the dump. The \fIsavecore\fP\|(8) +program then copies the information from the dump partition to +a file in a ``crash'' directory and also makes a copy of the +system which was running at the time of the crash (usually +``/kernel''). The offset to the system dump is defined in the +system variable \fIdumplo\fP (a sector offset from +the front of the dump partition). The +.I savecore +program operates by reading the contents of \fIdumplo\fP, \fIdumpdev\fP, +and \fIdumpmagic\fP from /dev/kmem, then comparing the value +of \fIdumpmagic\fP read from /dev/kmem to that located in +corresponding location in the dump area of the dump partition. +If a match is found, +.I savecore +assumes a crash occurred and reads \fIdumpsize\fP from the dump area +of the dump partition. This value is then used in copying the +system dump. Refer to +\fIsavecore\fP\|(8) +for more information about its operation. +.PP +The value \fIdumplo\fP is calculated to be +.DS +\fIdumpdev-size\fP \- \fImemsize\fP +.DE +where \fIdumpdev-size\fP is the size of the disk partition +where system dumps are to be placed, and +\fImemsize\fP is the size of physical memory. +If the disk partition is not large enough to hold a full +dump, \fIdumplo\fP is set to 0 (the start of the partition). -- cgit v1.1