BSD FreeBSD Architecture Handbook (2003).pdf

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FreeBSD Architecture Handbook
The FreeBSD Documentation Project
FreeBSD Architecture Handbook
by The FreeBSD Documentation Project
Published August 2000
Copyright © 2000, 2001, 2002, 2003 The FreeBSD Documentation Project
Welcome to the FreeBSD Architecture Handbook. This manual is a work in progress and is the work of many
individuals. Many sections do not yet exist and some of those that do exist need to be updated. If you are interested
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Table of Contents
I. Kernel ..................................................................................................................................................................... viii
1 Bootstrapping and kernel initialization ..............................................................................................................1
1.1 Synopsis .................................................................................................................................................1
1.2 Overview................................................................................................................................................1
1.3 BIOS POST ...........................................................................................................................................2
1.4 boot0 stage ...........................................................................................................................................2
1.5 boot2 stage ...........................................................................................................................................3
1.6 loader stage ...........................................................................................................................................6
1.7 Kernel initialization ...............................................................................................................................6
2 Locking Notes ..................................................................................................................................................15
2.1 Mutexes................................................................................................................................................15
2.2 Shared Exclusive Locks.......................................................................................................................18
2.3 Atomically Protected Variables ...........................................................................................................18
3 Kernel Objects ..................................................................................................................................................19
3.1 Terminology.........................................................................................................................................19
3.2 Kobj Operation ....................................................................................................................................19
3.3 Using Kobj ...........................................................................................................................................19
4 The Jail Subsystem...........................................................................................................................................23
4.1 Architecture .........................................................................................................................................23
4.2 Restrictions ..........................................................................................................................................26
5 The Sysinit Framework ....................................................................................................................................31
5.1 Terminology.........................................................................................................................................31
5.2 Sysinit Operation .................................................................................................................................31
5.3 Using Sysinit........................................................................................................................................31
6 The TrustedBSD MAC Framework..................................................................................................................33
6.1 MAC Documentation Copyright..........................................................................................................33
6.2 Synopsis ...............................................................................................................................................33
6.3 Introduction..........................................................................................................................................33
6.4 Policy Background...............................................................................................................................34
6.5 MAC Framework Kernel Architecture ................................................................................................34
6.6 MAC Policy Architecture ....................................................................................................................37
6.7 MAC Policy Entry Point Reference.....................................................................................................39
6.8 Userland Architecture ..........................................................................................................................93
6.9 Conclusion ...........................................................................................................................................94
7 Virtual Memory System ...................................................................................................................................95
7.1 Management of physical memory— vm_page_t ................................................................................95
7.2 The unified buffer cache— vm_object_t ...........................................................................................95
7.3 Filesystem I/O— struct buf ............................................................................................................96
7.4 Mapping Page Tables— vm_map_t, vm_entry_t ............................................................................96
7.5 KVM Memory Mapping......................................................................................................................96
7.6 Tuning the FreeBSD VM system.........................................................................................................97
8 SMPng Design Document ................................................................................................................................99
8.1 Introduction..........................................................................................................................................99
8.2 Basic Tools and Locking Fundamentals ..............................................................................................99
8.3 General Architecture and Design.......................................................................................................100
iv
8.4 Specific Locking Strategies ...............................................................................................................103
8.5 Implementation Notes........................................................................................................................107
8.6 Miscellaneous Topics.........................................................................................................................107
Glossary ...................................................................................................................................................108
9 * UFS..............................................................................................................................................................110
10 * AFS............................................................................................................................................................111
11 * Syscons......................................................................................................................................................112
12 * Compatibility Layers.................................................................................................................................113
12.1 * Linux.............................................................................................................................................113
II. Device Drivers ......................................................................................................................................................114
13 Writing FreeBSD Device Drivers.................................................................................................................115
13.1 Introduction......................................................................................................................................115
13.2 Dynamic Kernel Linker Facility - KLD...........................................................................................115
13.3 Accessing a device driver ................................................................................................................116
13.4 Character Devices ............................................................................................................................117
13.5 Network Drivers...............................................................................................................................120
14 ISA device drivers ........................................................................................................................................122
14.1 Synopsis ...........................................................................................................................................122
14.2 Basic information.............................................................................................................................122
14.3 Device_t pointer...............................................................................................................................124
14.4 Configuration file and the order of identifying and probing during auto-configuration..................124
14.5 Resources .........................................................................................................................................126
14.6 Bus memory mapping......................................................................................................................129
14.7 DMA ................................................................................................................................................136
14.8 xxx_isa_probe..................................................................................................................................138
14.9 xxx_isa_attach .................................................................................................................................143
14.10 xxx_isa_detach ..............................................................................................................................146
14.11 xxx_isa_shutdown .........................................................................................................................147
14.12 xxx_intr..........................................................................................................................................147
15 PCI Devices ..................................................................................................................................................149
15.1 Probe and Attach..............................................................................................................................149
15.2 Bus Resources..................................................................................................................................152
16 Common Access Method SCSI Controllers.................................................................................................156
16.1 Synopsis ...........................................................................................................................................156
16.2 General architecture.........................................................................................................................156
16.3 Polling..............................................................................................................................................174
16.4 Asynchronous Events ......................................................................................................................174
16.5 Interrupts..........................................................................................................................................175
16.6 Errors Summary...............................................................................................................................181
16.7 Timeout Handling ............................................................................................................................182
17 USB Devices ................................................................................................................................................184
17.1 Introduction......................................................................................................................................184
17.2 Host Controllers...............................................................................................................................185
17.3 USB Device Information .................................................................................................................187
17.4 Device probe and attach...................................................................................................................188
17.5 USB Drivers Protocol Information ..................................................................................................189
18 Newbus .........................................................................................................................................................192
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