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1 | .\" Copyright (c) 1983 The Regents of the University of California. |
2 | .\" All rights reserved. | |
3 | .\" | |
4 | .\" Redistribution and use in source and binary forms, with or without | |
5 | .\" modification, are permitted provided that the following conditions | |
6 | .\" are met: | |
7 | .\" 1. Redistributions of source code must retain the above copyright | |
8 | .\" notice, this list of conditions and the following disclaimer. | |
9 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
10 | .\" notice, this list of conditions and the following disclaimer in the | |
11 | .\" documentation and/or other materials provided with the distribution. | |
12 | .\" 3. All advertising materials mentioning features or use of this software | |
13 | .\" must display the following acknowledgement: | |
14 | .\" This product includes software developed by the University of | |
15 | .\" California, Berkeley and its contributors. | |
16 | .\" 4. Neither the name of the University nor the names of its contributors | |
17 | .\" may be used to endorse or promote products derived from this software | |
18 | .\" without specific prior written permission. | |
19 | .\" | |
20 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
21 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
22 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
23 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
24 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
25 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
26 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
27 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
28 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
29 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
30 | .\" SUCH DAMAGE. | |
31 | .\" | |
32 | .\" @(#)1.0.t 6.3 (Berkeley) 4/17/91 | |
33 | .\" | |
34 | .ds ss 1 | |
35 | .sh "Kernel primitives | |
36 | .PP | |
37 | The facilities available to a UNIX user process are logically | |
38 | divided into two parts: kernel facilities directly implemented by | |
39 | UNIX code running in the operating system, and system facilities | |
40 | implemented either by the system, or in cooperation with a | |
41 | \fIserver process\fP. These kernel facilities are described in | |
42 | this section 1. | |
43 | .PP | |
44 | The facilities implemented in the kernel are those which define the | |
45 | \fIUNIX virtual machine\fP in which each process runs. | |
46 | Like many real machines, this virtual machine has memory management hardware, | |
47 | an interrupt facility, timers and counters. The UNIX | |
48 | virtual machine also allows access to files and other objects through a set of | |
49 | \fIdescriptors\fP. Each descriptor resembles a device controller, | |
50 | and supports a set of operations. Like devices on real machines, some | |
51 | of which are internal to the machine and some of which are external, | |
52 | parts of the descriptor machinery are built-in to the operating system, while | |
53 | other parts are often implemented in server processes on other machines. | |
54 | The facilities provided through the descriptor machinery are described in | |
55 | section 2. | |
56 | .ds ss 2 |