| 1 | <?xml version="1.0" encoding="UTF-8"?>
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| 2 | <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
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| 3 | "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
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| 4 |
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| 5 | <book id="LinuxKernelAPI">
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| 6 | <bookinfo>
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| 7 | <title>The Linux Kernel API</title>
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| 8 |
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| 9 | <legalnotice>
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| 10 | <para>
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| 11 | This documentation is free software; you can redistribute
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| 12 | it and/or modify it under the terms of the GNU General Public
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| 13 | License as published by the Free Software Foundation; either
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| 14 | version 2 of the License, or (at your option) any later
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| 15 | version.
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| 16 | </para>
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| 17 |
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| 18 | <para>
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| 19 | This program is distributed in the hope that it will be
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| 20 | useful, but WITHOUT ANY WARRANTY; without even the implied
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| 21 | warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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| 22 | See the GNU General Public License for more details.
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| 23 | </para>
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| 24 |
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| 25 | <para>
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| 26 | You should have received a copy of the GNU General Public
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| 27 | License along with this program; if not, write to the Free
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| 28 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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| 29 | MA 02111-1307 USA
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| 30 | </para>
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| 31 |
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| 32 | <para>
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| 33 | For more details see the file COPYING in the source
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| 34 | distribution of Linux.
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| 35 | </para>
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| 36 | </legalnotice>
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| 37 | </bookinfo>
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| 38 |
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| 39 | <toc></toc>
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| 40 |
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| 41 | <chapter id="adt">
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| 42 | <title>Data Types</title>
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| 43 | <sect1><title>Doubly Linked Lists</title>
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| 44 | !Iinclude/linux/list.h
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| 45 | </sect1>
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| 46 | </chapter>
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| 47 |
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| 48 | <chapter id="libc">
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| 49 | <title>Basic C Library Functions</title>
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| 50 |
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| 51 | <para>
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| 52 | When writing drivers, you cannot in general use routines which are
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| 53 | from the C Library. Some of the functions have been found generally
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| 54 | useful and they are listed below. The behaviour of these functions
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| 55 | may vary slightly from those defined by ANSI, and these deviations
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| 56 | are noted in the text.
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| 57 | </para>
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| 58 |
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| 59 | <sect1><title>String Conversions</title>
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| 60 | !Elib/vsprintf.c
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| 61 | !Finclude/linux/kernel.h kstrtol
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| 62 | !Finclude/linux/kernel.h kstrtoul
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| 63 | !Elib/kstrtox.c
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| 64 | </sect1>
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| 65 | <sect1><title>String Manipulation</title>
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| 66 | |
| 67 | X!Ilib/string.c
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| 68 |
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| 69 | !Elib/string.c
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| 70 | </sect1>
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| 71 | <sect1><title>Bit Operations</title>
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| 72 | !Iarch/x86/include/asm/bitops.h
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| 73 | </sect1>
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| 74 | </chapter>
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| 75 |
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| 76 | <chapter id="kernel-lib">
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| 77 | <title>Basic Kernel Library Functions</title>
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| 78 |
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| 79 | <para>
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| 80 | The Linux kernel provides more basic utility functions.
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| 81 | </para>
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| 82 |
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| 83 | <sect1><title>Bitmap Operations</title>
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| 84 | !Elib/bitmap.c
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| 85 | !Ilib/bitmap.c
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| 86 | </sect1>
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| 87 |
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| 88 | <sect1><title>Command-line Parsing</title>
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| 89 | !Elib/cmdline.c
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| 90 | </sect1>
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| 91 |
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| 92 | <sect1 id="crc"><title>CRC Functions</title>
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| 93 | !Elib/crc7.c
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| 94 | !Elib/crc16.c
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| 95 | !Elib/crc-itu-t.c
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| 96 | !Elib/crc32.c
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| 97 | !Elib/crc-ccitt.c
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| 98 | </sect1>
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| 99 |
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| 100 | <sect1 id="idr"><title>idr/ida Functions</title>
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| 101 | !Pinclude/linux/idr.h idr sync
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| 102 | !Plib/idr.c IDA description
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| 103 | !Elib/idr.c
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| 104 | </sect1>
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| 105 | </chapter>
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| 106 |
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| 107 | <chapter id="mm">
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| 108 | <title>Memory Management in Linux</title>
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| 109 | <sect1><title>The Slab Cache</title>
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| 110 | !Iinclude/linux/slab.h
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| 111 | !Emm/slab.c
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| 112 | </sect1>
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| 113 | <sect1><title>User Space Memory Access</title>
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| 114 | !Iarch/x86/include/asm/uaccess_32.h
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| 115 | !Earch/x86/lib/usercopy_32.c
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| 116 | </sect1>
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| 117 | <sect1><title>More Memory Management Functions</title>
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| 118 | !Emm/readahead.c
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| 119 | !Emm/filemap.c
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| 120 | !Emm/memory.c
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| 121 | !Emm/vmalloc.c
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| 122 | !Imm/page_alloc.c
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| 123 | !Emm/mempool.c
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| 124 | !Emm/dmapool.c
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| 125 | !Emm/page-writeback.c
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| 126 | !Emm/truncate.c
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| 127 | </sect1>
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| 128 | </chapter>
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| 129 |
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| 130 |
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| 131 | <chapter id="ipc">
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| 132 | <title>Kernel IPC facilities</title>
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| 133 |
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| 134 | <sect1><title>IPC utilities</title>
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| 135 | !Iipc/util.c
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| 136 | </sect1>
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| 137 | </chapter>
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| 138 |
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| 139 | <chapter id="kfifo">
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| 140 | <title>FIFO Buffer</title>
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| 141 | <sect1><title>kfifo interface</title>
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| 142 | !Iinclude/linux/kfifo.h
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| 143 | </sect1>
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| 144 | </chapter>
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| 145 |
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| 146 | <chapter id="relayfs">
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| 147 | <title>relay interface support</title>
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| 148 |
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| 149 | <para>
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| 150 | Relay interface support
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| 151 | is designed to provide an efficient mechanism for tools and
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| 152 | facilities to relay large amounts of data from kernel space to
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| 153 | user space.
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| 154 | </para>
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| 155 |
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| 156 | <sect1><title>relay interface</title>
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| 157 | !Ekernel/relay.c
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| 158 | !Ikernel/relay.c
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| 159 | </sect1>
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| 160 | </chapter>
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| 161 |
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| 162 | <chapter id="modload">
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| 163 | <title>Module Support</title>
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| 164 | <sect1><title>Module Loading</title>
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| 165 | !Ekernel/kmod.c
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| 166 | </sect1>
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| 167 | <sect1><title>Inter Module support</title>
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| 168 | <para>
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| 169 | Refer to the file kernel/module.c for more information.
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| 170 | </para>
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| 171 | |
| 172 | X!Ekernel/module.c
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| 173 |
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| 174 | </sect1>
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| 175 | </chapter>
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| 176 |
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| 177 | <chapter id="hardware">
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| 178 | <title>Hardware Interfaces</title>
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| 179 | <sect1><title>Interrupt Handling</title>
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| 180 | !Ekernel/irq/manage.c
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| 181 | </sect1>
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| 182 |
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| 183 | <sect1><title>DMA Channels</title>
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| 184 | !Ekernel/dma.c
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| 185 | </sect1>
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| 186 |
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| 187 | <sect1><title>Resources Management</title>
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| 188 | !Ikernel/resource.c
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| 189 | !Ekernel/resource.c
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| 190 | </sect1>
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| 191 |
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| 192 | <sect1><title>MTRR Handling</title>
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| 193 | !Earch/x86/kernel/cpu/mtrr/main.c
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| 194 | </sect1>
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| 195 |
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| 196 | <sect1><title>PCI Support Library</title>
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| 197 | !Edrivers/pci/pci.c
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| 198 | !Edrivers/pci/pci-driver.c
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| 199 | !Edrivers/pci/remove.c
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| 200 | !Edrivers/pci/search.c
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| 201 | !Edrivers/pci/msi.c
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| 202 | !Edrivers/pci/bus.c
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| 203 | !Edrivers/pci/access.c
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| 204 | !Edrivers/pci/irq.c
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| 205 | !Edrivers/pci/htirq.c
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| 206 | |
| 207 | X!Edrivers/pci/hotplug.c
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| 208 |
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| 209 | !Edrivers/pci/probe.c
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| 210 | !Edrivers/pci/slot.c
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| 211 | !Edrivers/pci/rom.c
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| 212 | !Edrivers/pci/iov.c
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| 213 | !Idrivers/pci/pci-sysfs.c
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| 214 | </sect1>
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| 215 | <sect1><title>PCI Hotplug Support Library</title>
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| 216 | !Edrivers/pci/hotplug/pci_hotplug_core.c
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| 217 | </sect1>
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| 218 | </chapter>
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| 219 |
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| 220 | <chapter id="firmware">
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| 221 | <title>Firmware Interfaces</title>
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| 222 | <sect1><title>DMI Interfaces</title>
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| 223 | !Edrivers/firmware/dmi_scan.c
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| 224 | </sect1>
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| 225 | <sect1><title>EDD Interfaces</title>
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| 226 | !Idrivers/firmware/edd.c
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| 227 | </sect1>
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| 228 | </chapter>
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| 229 |
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| 230 | <chapter id="security">
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| 231 | <title>Security Framework</title>
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| 232 | !Isecurity/security.c
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| 233 | !Esecurity/inode.c
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| 234 | </chapter>
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| 235 |
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| 236 | <chapter id="audit">
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| 237 | <title>Audit Interfaces</title>
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| 238 | !Ekernel/audit.c
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| 239 | !Ikernel/auditsc.c
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| 240 | !Ikernel/auditfilter.c
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| 241 | </chapter>
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| 242 |
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| 243 | <chapter id="accounting">
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| 244 | <title>Accounting Framework</title>
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| 245 | !Ikernel/acct.c
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| 246 | </chapter>
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| 247 |
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| 248 | <chapter id="blkdev">
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| 249 | <title>Block Devices</title>
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| 250 | !Eblock/blk-core.c
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| 251 | !Iblock/blk-core.c
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| 252 | !Eblock/blk-map.c
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| 253 | !Iblock/blk-sysfs.c
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| 254 | !Eblock/blk-settings.c
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| 255 | !Eblock/blk-exec.c
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| 256 | !Eblock/blk-flush.c
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| 257 | !Eblock/blk-lib.c
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| 258 | !Eblock/blk-tag.c
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| 259 | !Iblock/blk-tag.c
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| 260 | !Eblock/blk-integrity.c
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| 261 | !Ikernel/trace/blktrace.c
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| 262 | !Iblock/genhd.c
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| 263 | !Eblock/genhd.c
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| 264 | </chapter>
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| 265 |
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| 266 | <chapter id="chrdev">
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| 267 | <title>Char devices</title>
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| 268 | !Efs/char_dev.c
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| 269 | </chapter>
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| 270 |
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| 271 | <chapter id="miscdev">
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| 272 | <title>Miscellaneous Devices</title>
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| 273 | !Edrivers/char/misc.c
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| 274 | </chapter>
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| 275 |
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| 276 | <chapter id="clk">
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| 277 | <title>Clock Framework</title>
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| 278 |
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| 279 | <para>
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| 280 | The clock framework defines programming interfaces to support
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| 281 | software management of the system clock tree.
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| 282 | This framework is widely used with System-On-Chip (SOC) platforms
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| 283 | to support power management and various devices which may need
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| 284 | custom clock rates.
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| 285 | Note that these "clocks" don't relate to timekeeping or real
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| 286 | time clocks (RTCs), each of which have separate frameworks.
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| 287 | These <structname>struct clk</structname> instances may be used
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| 288 | to manage for example a 96 MHz signal that is used to shift bits
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| 289 | into and out of peripherals or busses, or otherwise trigger
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| 290 | synchronous state machine transitions in system hardware.
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| 291 | </para>
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| 292 |
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| 293 | <para>
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| 294 | Power management is supported by explicit software clock gating:
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| 295 | unused clocks are disabled, so the system doesn't waste power
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| 296 | changing the state of transistors that aren't in active use.
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| 297 | On some systems this may be backed by hardware clock gating,
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| 298 | where clocks are gated without being disabled in software.
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| 299 | Sections of chips that are powered but not clocked may be able
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| 300 | to retain their last state.
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| 301 | This low power state is often called a <emphasis>retention
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| 302 | mode</emphasis>.
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| 303 | This mode still incurs leakage currents, especially with finer
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| 304 | circuit geometries, but for CMOS circuits power is mostly used
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| 305 | by clocked state changes.
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| 306 | </para>
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| 307 |
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| 308 | <para>
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| 309 | Power-aware drivers only enable their clocks when the device
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| 310 | they manage is in active use. Also, system sleep states often
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| 311 | differ according to which clock domains are active: while a
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| 312 | "standby" state may allow wakeup from several active domains, a
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| 313 | "mem" (suspend-to-RAM) state may require a more wholesale shutdown
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| 314 | of clocks derived from higher speed PLLs and oscillators, limiting
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| 315 | the number of possible wakeup event sources. A driver's suspend
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| 316 | method may need to be aware of system-specific clock constraints
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| 317 | on the target sleep state.
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| 318 | </para>
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| 319 |
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| 320 | <para>
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| 321 | Some platforms support programmable clock generators. These
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| 322 | can be used by external chips of various kinds, such as other
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| 323 | CPUs, multimedia codecs, and devices with strict requirements
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| 324 | for interface clocking.
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| 325 | </para>
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| 326 |
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| 327 | !Iinclude/linux/clk.h
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| 328 | </chapter>
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| 329 |
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| 330 | </book>
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