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source: vbox/trunk/src/VBox/ValidationKit/bootsectors/bs3kit/bs3kit-docs.c@ 84794

Last change on this file since 84794 was 82968, checked in by vboxsync, 5 years ago

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1/* $Id: bs3kit-docs.c 82968 2020-02-04 10:35:17Z vboxsync $ */
2/** @file
3 * BS3Kit - Documentation.
4 */
5
6/*
7 * Copyright (C) 2007-2020 Oracle Corporation
8 *
9 * This file is part of VirtualBox Open Source Edition (OSE), as
10 * available from http://www.virtualbox.org. This file is free software;
11 * you can redistribute it and/or modify it under the terms of the GNU
12 * General Public License (GPL) as published by the Free Software
13 * Foundation, in version 2 as it comes in the "COPYING" file of the
14 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16 *
17 * The contents of this file may alternatively be used under the terms
18 * of the Common Development and Distribution License Version 1.0
19 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
20 * VirtualBox OSE distribution, in which case the provisions of the
21 * CDDL are applicable instead of those of the GPL.
22 *
23 * You may elect to license modified versions of this file under the
24 * terms and conditions of either the GPL or the CDDL or both.
25 */
26
27
28
29/** @page pg_bs3kit BS3Kit - Boot Sector Kit \#3
30 *
31 * The BS3Kit is a framework for bare metal floppy/usb image tests.
32 *
33 * The 3rd iteration of the framework includes support for 16-bit and 32-bit
34 * C/C++ code, with provisions for 64-bit C code to possibly be added later.
35 * The C code have to do without a runtime library, otherwhat what we can share
36 * possibly with IPRT.
37 *
38 * This iteration also adds a real linker into the picture, which is an
39 * improvment over early when all had to done in a single assembler run with
40 * lots of includes and macros controlling what we needed. The functions are no
41 * in separate files and compiled/assembled into libraries, so the linker will
42 * only include exactly what is needed. The current linker is the OpenWatcom
43 * one, wlink, that we're already using when building the BIOSes. If it wasn't
44 * for the segment/selector fixups in 16-bit code (mostly), maybe we could
45 * convince the ELF linker from GNU binutils to do the job too (with help from
46 * the ).
47 *
48 *
49 * @sa grp_bs3kit, grp_bs3kit_tmpl, grp_bs3kit_cmn, grp_bs3kit_mode,
50 * grp_bs3kit_system
51 *
52 * @section sec_calling_convention Calling convention
53 *
54 * Because we're not mixing with C code, we will use __cdecl for 16-bit and
55 * 32-bit code, where as 64-bit code will use the microsoft calling AMD64
56 * convention. To avoid unnecessary %ifdef'ing in assembly code, we will use a
57 * macro to load the RCX, RDX, R8 and R9 registers off the stack in 64-bit
58 * assembly code.
59 *
60 * Register treatment in 16-bit __cdecl, 32-bit __cdecl and 64-bit msabi:
61 *
62 * | Register | 16-bit | 32-bit | 64-bit | ASM template |
63 * | ------------ | ----------- | ---------- | --------------- | ------------ |
64 * | EAX, RAX | volatile | volatile | volatile | volatile |
65 * | EBX, RBX | volatile | preserved | preserved | both |
66 * | ECX, RCX | volatile | volatile | volatile, arg 0 | volatile |
67 * | EDX, RDX | volatile | volatile | volatile, arg 1 | volatile |
68 * | ESP, RSP | preserved | preserved | preserved | preserved |
69 * | EBP, RBP | preserved | preserved | preserved | preserved |
70 * | EDI, RDI | preserved | preserved | preserved | preserved |
71 * | ESI, RSI | preserved | preserved | preserved | preserved |
72 * | R8 | volatile | volatile | volatile, arg 2 | volatile |
73 * | R9 | volatile | volatile | volatile, arg 3 | volatile |
74 * | R10 | volatile | volatile | volatile | volatile |
75 * | R11 | volatile | volatile | volatile | volatile |
76 * | R12 | volatile | volatile | preserved | preserved(*) |
77 * | R13 | volatile | volatile | preserved | preserved(*) |
78 * | R14 | volatile | volatile | preserved | preserved(*) |
79 * | R15 | volatile | volatile | preserved | preserved(*) |
80 * | RFLAGS.DF | =0 | =0 | =0 | =0 |
81 * | CS | preserved | preserved | preserved | preserved |
82 * | DS | preserved! | preserved? | preserved | both |
83 * | ES | volatile | volatile | preserved | volatile |
84 * | FS | preserved | preserved | preserved | preserved |
85 * | GS | preserved | volatile | preserved | both |
86 * | SS | preserved | preserved | preserved | preserved |
87 *
88 * The 'both' here means that we preserve it wrt to our caller, while at the
89 * same time assuming anything we call will clobber it.
90 *
91 * The 'preserved(*)' marking of R12-R15 indicates that they'll be preserved in
92 * 64-bit mode, but may be changed in certain cases when running 32-bit or
93 * 16-bit code. This is especially true if switching CPU mode, e.g. from 32-bit
94 * protected mode to 32-bit long mode.
95 *
96 * Return values are returned in the xAX register, but with the following
97 * caveats for values larger than ARCH_BITS:
98 * - 16-bit code:
99 * - 32-bit values are returned in AX:DX, where AX holds bits 15:0 and
100 * DX bits 31:16.
101 * - 64-bit values are returned in DX:CX:BX:AX, where DX holds bits
102 * 15:0, CX bits 31:16, BX bits 47:32, and AX bits 63:48.
103 * - 32-bit code:
104 * - 64-bit values are returned in EAX:EDX, where eax holds the least
105 * significant bits.
106 *
107 * The DS segment register is pegged to BS3DATA16_GROUP in 16-bit code so that
108 * we don't need to reload it all the time. This allows us to modify it in
109 * ring-0 and mode switching code without ending up in any serious RPL or DPL
110 * trouble. In 32-bit and 64-bit mode the DS register is a flat, unlimited,
111 * writable selector.
112 *
113 * In 16-bit and 32-bit code we do not assume anything about ES, FS, and GS.
114 *
115 *
116 * For an in depth coverage of x86 and AMD64 calling convensions, see
117 * http://homepage.ntlworld.com/jonathan.deboynepollard/FGA/function-calling-conventions.html
118 *
119 *
120 *
121 * @section sec_modes Execution Modes
122 *
123 * BS3Kit defines a number of execution modes in order to be able to test the
124 * full CPU capabilities (that VirtualBox care about anyways). It currently
125 * omits system management mode, hardware virtualization modes, and security
126 * modes as those aren't supported by VirtualBox or are difficult to handle.
127 *
128 * The modes are categorized into normal and weird ones.
129 *
130 * The normal ones are:
131 * + RM - Real mode.
132 * + PE16 - Protected mode running 16-bit code, 16-bit TSS and 16-bit handlers.
133 * + PE32 - Protected mode running 32-bit code, 32-bit TSS and 32-bit handlers.
134 * + PEV86 - Protected mode running v8086 code, 32-bit TSS and 32-bit handlers.
135 * + PP16 - 386 paged mode running 16-bit code, 16-bit TSS and 16-bit handlers.
136 * + PP32 - 386 paged mode running 32-bit code, 32-bit TSS and 32-bit handlers.
137 * + PPV86 - 386 paged mode running v8086 code, 32-bit TSS and 32-bit handlers.
138 * + PAE16 - PAE paged mode running 16-bit code, 16-bit TSS and 16-bit handlers.
139 * + PAE32 - PAE paged mode running 32-bit code, 32-bit TSS and 32-bit handlers.
140 * + PAEV86 - PAE paged mode running v8086 code, 32-bit TSS and 32-bit handlers.
141 * + LM16 - AMD64 long mode running 16-bit code, 64-bit TSS and 64-bit handlers.
142 * + LM32 - AMD64 long mode running 32-bit code, 64-bit TSS and 64-bit handlers.
143 * + LM64 - AMD64 long mode running 64-bit code, 64-bit TSS and 64-bit handlers.
144 *
145 * The weird ones:
146 * + PE16_32 - Protected mode running 16-bit code, 16-bit TSS and 16-bit handlers.
147 * + PE16_V86 - Protected mode running 16-bit code, 16-bit TSS and 16-bit handlers.
148 * + PE32_16 - Protected mode running 32-bit code, 32-bit TSS and 32-bit handlers.
149 * + PP16_32 - 386 paged mode running 16-bit code, 16-bit TSS and 16-bit handlers.
150 * + PP16_V86 - 386 paged mode running 16-bit code, 16-bit TSS and 16-bit handlers.
151 * + PP32_16 - 386 paged mode running 32-bit code, 32-bit TSS and 32-bit handlers.
152 * + PAE16_32 - PAE paged mode running 16-bit code, 16-bit TSS and 16-bit handlers.
153 * + PAE16_V86 - PAE paged mode running 16-bit code, 16-bit TSS and 16-bit handlers.
154 * + PAE32_16 - PAE paged mode running 32-bit code, 32-bit TSS and 32-bit handlers.
155 *
156 * Actually, the PE32_16, PP32_16 and PAE32_16 modes aren't all that weird and fits in
157 * right next to LM16 and LM32, but this is the way it ended up. :-)
158 *
159 */
160
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