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pascal@15368
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1 /*
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2 Copyright (C) 2000, Entity Cyber, Inc.
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3
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4 Authors: Gary Byers (gb@thinguin.org)
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5 Marty Connor (mdc@thinguin.org)
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6
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7 This software may be used and distributed according to the terms
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8 of the GNU Public License (GPL), incorporated herein by reference.
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9
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10 Description:
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11
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12 This is just a little bit of code and data that can get prepended
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13 to a ROM image in order to allow bootloaders to load the result
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14 as if it were a Linux kernel image.
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15
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16 A real Linux kernel image consists of a one-sector boot loader
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17 (to load the image from a floppy disk), followed a few sectors
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18 of setup code, followed by the kernel code itself. There's
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19 a table in the first sector (starting at offset 497) that indicates
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20 how many sectors of setup code follow the first sector and which
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21 contains some other parameters that aren't interesting in this
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22 case.
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23
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24 We don't require much in the way of setup code. Historically, the
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25 Linux kernel required at least 4 sectors of setup code.
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26 Therefore, at least 4 sectors must be present even though we don't
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27 use them.
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28
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29 */
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30
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31 FILE_LICENCE ( GPL_ANY )
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32
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33 #define SETUPSECS 4 /* Minimal nr of setup-sectors */
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34 #define PREFIXSIZE ((SETUPSECS+1)*512)
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35 #define PREFIXPGH (PREFIXSIZE / 16 )
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36 #define BOOTSEG 0x07C0 /* original address of boot-sector */
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37 #define INITSEG 0x9000 /* we move boot here - out of the way */
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38 #define SETUPSEG 0x9020 /* setup starts here */
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39 #define SYSSEG 0x1000 /* system loaded at 0x10000 (65536). */
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40
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41 .text
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42 .code16
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43 .arch i386
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44 .org 0
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45 .section ".prefix", "ax", @progbits
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46 .globl _lkrn_start
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47 _lkrn_start:
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48
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49 bootsector:
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50 _start:
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51
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52 /* some extra features */
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53 #define EXE_SUPPORT real mode dos .exe file support
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54
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55 #define EXEADRS(x) (x+0xE0)
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56
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57 /* some contraints to reduce the size */
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58 //#define FLOPPY_1440K_ONLY 1.44M floppies support only
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59
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60 #ifdef EXE_SUPPORT
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61 /* Initial temporary stack size */
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62 #define EXE_STACK_SIZE 0x400
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63
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64 /* Temporary decompression area (avoid DOS high memory area) */
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65 #define EXE_DECOMPRESS_ADDRESS 0x110000
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66
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67 /* Fields within the Program Segment Prefix */
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68 #define PSP_CMDLINE_LEN 0x80
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69 #define PSP_CMDLINE_START 0x81
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70
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71 #define HEADER_SIZE 0x20
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72
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73 signature:
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74 decw %bp // Magic number: MZ
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75 popw %dx
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76 jmp start // Bytes on last page of file
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77 blocks:
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78 .word 0 // Pages in file
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79 .section ".zinfo.fixup", "a", @progbits /* Compressor fixups */
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80 .ascii "ADDW"
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81 .long blocks
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82 .long 512
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83 .long 0
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84 .previous
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85 .word 0 // Relocations
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86 .word ( HEADER_SIZE / 16 ) // Size of header in paragraphs
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87 .word ( EXE_STACK_SIZE / 16 ) // Minimum extra paragraphs needed
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88 .word ( EXE_STACK_SIZE / 16 ) // Maximum extra paragraphs needed
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89 init_ss:
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90 .word -( ( _exe_start - signature ) / 16 ) // Initial (relative) SS value
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91 .section ".zinfo.fixup", "a", @progbits /* Compressor fixups */
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92 .ascii "ADDW"
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93 .long init_ss
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94 .long 16
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95 .long 0
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96 .previous
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97 .word EXE_STACK_SIZE // Initial SP value
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98 .word 0 // Checksum
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99 .word _exe_start // Initial IP value
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100 /* Initial code segment (relative to start of executable) */
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101 .word -( HEADER_SIZE / 16 ) // Initial (relative) CS value
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102 // .word 0x001C // File address of relocation table
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103 // .word 0,0,0 // Overlay number
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104
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105 start:
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106 pushw %dx
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107 xorw %dx, %dx
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108 #endif
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109 cld # assume nothing
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110 stacktop = 0x9E00 # in 0x8000 .. 0xA000
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111 zeroed = 12 # zeroed registers
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112 movw $stacktop-12-zeroed, %di # stacktop is an arbitrary value >=
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113 # length of bootsect + length of
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114 # setup + room for stack;
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115 # 12 is disk parm size.
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116 pushw $INITSEG
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117 popw %ss # %ss contain INITSEG
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118 movw %di, %sp # put stack at INITSEG:stacktop-...
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119
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120 # Many BIOS's default disk parameter tables will not recognize
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121 # multi-sector reads beyond the maximum sector number specified
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122 # in the default diskette parameter tables - this may mean 7
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123 # sectors in some cases.
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124 #
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125 # Since single sector reads are slow and out of the question,
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126 # we must take care of this by creating new parameter tables
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127 # (for the first disk) in RAM. We can set the maximum sector
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128 # count to 36 - the most we will encounter on an ED 2.88.
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129 #
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130 # High doesn't hurt. Low does. Let's use the max: 63
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131
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132 pushw %ss
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133 popw %es # %es = %ss = INITSEG
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134 xorw %ax, %ax # %ax = 0
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135 movw $zeroed/2, %cx # clear gdt + offset, %ds, limits
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136 rep # don't worry about cld
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137 stosw # already done above
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138 popw %bx # offset = 0
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139 popw %ds # %ds = 0
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140 popw %fs # %fs = 0
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141
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142 movb setup_sects+0x7C00, %al # read bootsector + setup (%ds = 0)
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143 incw %ax
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144
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145 ldsw 0x78(%bx), %si # %ds:%bx+0x78 is parameter table address
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146 pushw %es
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147 pushw %di
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148 movb $6, %cl # copy 12 bytes
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149 rep # don't worry about cld
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150 movsw # already done above
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151 pushw %ss
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152 popw %ds # now %ds = %es = %ss = INITSEG
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153 popl %fs:0x78(%bx) # update parameter table address
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154 movb $63, 0x4-12(%di) # patch sector count, %di = stacktop
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155 cli
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156
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157 xchg %ax, %di # sector count
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158 popw %ax # limits = 0
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159 incw %cx # cylinder 0, sector 1, clear Z
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160 call read_first_sectors # read setup
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161
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162 # This routine loads the system at address LOADSEG, making sure
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163 # no 64kB boundaries are crossed. We try to load it as fast as
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164 # possible, loading whole tracks whenever we can.
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165
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166 popw %bx # clear %bx
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167 movw syssize, %di
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168 addw $(512/16)-1, %di
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169 shrw $9-4, %di
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170 movw $SYSSEG, %cx
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171 call read_sectorsCX
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172
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pascal@15368
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173 # This procedure turns off the floppy drive motor, so
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174 # that we enter the kernel in a known state, and
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175 # don't have to worry about it later.
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176
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177 kill_motor:
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178 xchgw %ax, %di # reset FDC (%di < 128)
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179 int $0x13
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180
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181 # After that (everything loaded), we jump to the setup-routine
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182 # loaded directly after the bootblock:
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183 # Segments are as follows: %ds = %ss = INITSEG
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184
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185 ljmp $SETUPSEG, $0
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186
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187 #ifdef EXE_SUPPORT
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188 dosexit:
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189 movw $0x4c00, %ax
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190 int $0x21
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191
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192 _exe_start:
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193 pushw $dosexit
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194 movw $EXEADRS(need386), %si
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195 pushfw // save flags
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196 // bits 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
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197 // flags 0 NT IOPL OF DF IF TF SF ZF 0 AF 0 PF 1 CF
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198 movb $0x10, %ah // DF = IF = TF = 0
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199 pushw %ax
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200 popfw // < 286 : flags[12..15] are forced 1
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201 pushfw // = 286 : flags[12..15] are forced 0
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202 popw %cx // > 286 : only flags[15] is forced 0
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203 popfw // restore flags
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204 addb %ah, %ch // test F0 and 00 cases
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205 cmpb %ah, %ch
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206 jbe puts // C=8086/80186, Z=80286
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207 // smsww %ax
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208 // andb $1, %al
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209 // jne puts
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210
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pascal@15368
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211 /* Terminate command line with a NUL */
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pascal@15368
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212 movzbw PSP_CMDLINE_LEN, %si
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213 movb $0, PSP_CMDLINE_START(%si)
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214 cmpb $'?', PSP_CMDLINE_START-1(%si)
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215 je help
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pascal@15368
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216 pushw %si
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217
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pascal@15368
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218 /* Install iPXE. Use a fixed temporary decompression area to
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219 * avoid trashing the DOS high memory area.
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220 */
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221 call alloc_basemem
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222 movl $EXE_DECOMPRESS_ADDRESS, %edi
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223 stc
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224 sbbl %ebp, %ebp /* Allow arbitrary relocation */
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225 xorl %esi, %esi
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pascal@15368
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226 call install_prealloc
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227
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228 xorl %ebp, %ebp
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229 xorl %ecx, %ecx
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230
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pascal@15368
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231 /* Calculate command line physical address */
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pascal@15368
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232 xorl %edx, %edx
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233 movw %ds, %dx
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234 shll $4, %edx
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235 popw %si
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236 orw %si, %si
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237 jne gotarg
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238 movw $EXEADRS(default_config), %bp
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239 addl %edx, %ebp
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240 movw $0xA00-default_config, %cx
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241 gotarg:
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242 addl $PSP_CMDLINE_START, %edx
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243
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pascal@15368
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244 jmp start_ipxe
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245
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246 help:
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247 movw $EXEADRS(helpmsg), %si
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248 puts:
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249 lodsb
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pascal@15368
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250 orb %al, %al
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pascal@15368
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251 je exit
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pascal@15368
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252 call putc
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253 jmp puts
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pascal@15368
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254 #endif
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pascal@15368
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255
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pascal@15368
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256 putcdot:
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257 movb $0x2E, %al
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258 putc:
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259 movb $0xE, %ah
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260 movw $7, %bx
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pascal@15368
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261 int $0x10
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262 exit:
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263 ret
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pascal@15368
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264
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pascal@15368
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265
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pascal@15368
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266 # read_sectors reads %di sectors into %es:0 buffer.
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267 # %es:0 is updated to the next memory location.
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pascal@15368
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268 # First, sectors are read sector by sector until
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269 # sector per track count is known. Then they are
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270 # read track by track.
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pascal@15368
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271 # Assume no error on first track.
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pascal@15368
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272
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pascal@15368
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273 #ifdef FLOPPY_1440K_ONLY
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pascal@15368
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274 #define FLOPPY_HEADS 2 /* 2 heads */
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pascal@15368
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275 #define FLOPPY_SECTORS 18 /* 18 sectors */
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pascal@15368
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276 #else
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pascal@15368
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277 #define FLOPPY_HEADS 2 /* 2 heads minimum */
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pascal@15368
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278 #define FLOPPY_SECTORS 9 /* 9 sectors minimum */
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pascal@15368
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279 #endif
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pascal@15368
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280
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pascal@15368
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281 check_limits:
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pascal@15368
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282 #ifndef FLOPPY_1440K_ONLY
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pascal@15368
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283 popw %dx
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pascal@15368
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284 #ifdef FLOPPY_SECTORS
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pascal@15368
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285 cmpb $FLOPPY_SECTORS+1, %cl # minimum sector count
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pascal@15368
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286 jb check_head
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pascal@15368
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287 #endif
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pascal@15368
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288 cmpb %al, %cl # max sector known ?
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pascal@15368
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289 ja next_head # no -> store it
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pascal@15368
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290 check_head:
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pascal@15368
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291 #ifdef FLOPPY_HEADS
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pascal@15368
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292 cmpb $FLOPPY_HEADS, %dh # 2 heads minimum
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pascal@15368
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293 jb check_cylinder
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pascal@15368
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294 #endif
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pascal@15368
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295 cmpb %ah, %dh # max head known ?
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pascal@15368
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296 ja next_cylinder # no -> store it
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pascal@15368
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297 check_cylinder:
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pascal@15368
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298 #endif
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pascal@15368
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299 pushaw
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pascal@15368
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300 #ifndef FLOPPY_1440K_ONLY
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pascal@15368
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301 cbw # %ah = 0
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pascal@15368
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302 #endif
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pascal@15368
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303 int $0x13 # reset controler
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pascal@15368
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304 popaw
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pascal@15368
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305 movb $1, %al # sector by sector...
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pascal@15368
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306 read_sectorslp:
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pascal@15368
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307 pushw %dx # some bios break dx...
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pascal@15368
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308 #ifndef FLOPPY_1440K_ONLY
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pascal@15368
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309 pushw %ax # limits
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pascal@15368
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310 subb %cl, %al # sectors remaining in track
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pascal@15368
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311 ja tolastsect
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pascal@15368
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312 movb $1, %al # 1 sector mini
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313 tolastsect:
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pascal@15368
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314 #else
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pascal@15368
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315 mov $FLOPPY_SECTORS+1, %al
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pascal@15368
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316 subb %cl, %al # sectors remaining in track
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pascal@15368
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317 #endif
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pascal@15368
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318 cbw
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pascal@15368
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319 cmpw %di, %ax
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pascal@15368
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320 jb more1trk
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pascal@15368
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321 movw %di, %ax # sectors to read
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pascal@15368
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322 more1trk:
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pascal@15368
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323 pushw %ax # save context
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pascal@15368
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324 movb $2, %ah # cmd: read chs
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pascal@15368
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325 int $0x13
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pascal@15368
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326 #ifndef FLOPPY_1440K_ONLY
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pascal@15368
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327 popw %dx # save %ax
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pascal@15368
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328 popw %ax # limits
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pascal@15368
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329 #else
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pascal@15368
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330 popw %ax # restore context
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pascal@15368
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331 popw %dx
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pascal@15368
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332 #endif
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pascal@15368
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333 jc check_limits
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pascal@15368
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334 #ifndef FLOPPY_1440K_ONLY
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pascal@15368
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335 xchgw %ax, %bp
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pascal@15368
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336 addw %dx,%cx # next sector
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pascal@15368
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337 movw %cx, %gs
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pascal@15368
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338 movw %es, %cx
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pascal@15368
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339 pushw %dx
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pascal@15368
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340 shlw $5, %dx
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pascal@15368
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341 addw %dx, %cx
|
pascal@15368
|
342 popw %dx
|
pascal@15368
|
343 subw %dx,%di # update sector counter
|
pascal@15368
|
344 popw %dx
|
pascal@15368
|
345 read_sectorsCX:
|
pascal@15368
|
346 movw %cx, %es # next location
|
pascal@15368
|
347 jz putcdot
|
pascal@15368
|
348 #else
|
pascal@15368
|
349 addw %ax,%cx # next sector
|
pascal@15368
|
350 movw %cx, %gs
|
pascal@15368
|
351 movw %es, %cx
|
pascal@15368
|
352 pushw %ax
|
pascal@15368
|
353 shlw $5, %ax
|
pascal@15368
|
354 addw %ax, %cx
|
pascal@15368
|
355 popw %ax
|
pascal@15368
|
356 subw %ax,%di # update sector counter
|
pascal@15368
|
357 read_sectorsCX:
|
pascal@15368
|
358 movw %cx, %es # next location
|
pascal@15368
|
359 jz putcdot
|
pascal@15368
|
360 #endif
|
pascal@15368
|
361 read_sectors:
|
pascal@15368
|
362 movw %gs, %cx
|
pascal@15368
|
363 #ifndef FLOPPY_1440K_ONLY
|
pascal@15368
|
364 # al is last sector+1
|
pascal@15368
|
365 # ah is last cylinder+1
|
pascal@15368
|
366 xchgw %ax, %bp
|
pascal@15368
|
367 #endif
|
pascal@15368
|
368 #ifndef FLOPPY_1440K_ONLY
|
pascal@15368
|
369 cmpb %al,%cl # reach sector limit ?
|
pascal@15368
|
370 jne bdendlp
|
pascal@15368
|
371 next_head:
|
pascal@15368
|
372 movb %cl,%al
|
pascal@15368
|
373 #else
|
pascal@15368
|
374 cmpb $FLOPPY_SECTORS+1,%cl # reach sector limit ?
|
pascal@15368
|
375 jne bdendlp
|
pascal@15368
|
376 #endif
|
pascal@15368
|
377 incb %dh # next head
|
pascal@15368
|
378 movb $1,%cl # first sector
|
pascal@15368
|
379 #ifndef FLOPPY_1440K_ONLY
|
pascal@15368
|
380 cmpb %ah, %dh # reach head limit ?
|
pascal@15368
|
381 jne bdendlp
|
pascal@15368
|
382 next_cylinder:
|
pascal@15368
|
383 movb %dh,%ah
|
pascal@15368
|
384 #else
|
pascal@15368
|
385 cmpb %cl,%dh # reach head limit ?
|
pascal@15368
|
386 je bdendlp
|
pascal@15368
|
387 #endif
|
pascal@15368
|
388 # NOTE : support 256 cylinders max
|
pascal@15368
|
389 incb %ch # next cylinder
|
pascal@15368
|
390 read_first_sectors:
|
pascal@15368
|
391 movb $0,%dh # first head
|
pascal@15368
|
392 bdendlp:
|
pascal@15368
|
393 jmp read_sectorslp
|
pascal@15368
|
394
|
pascal@15368
|
395 #ifdef EXE_SUPPORT
|
pascal@15368
|
396 need386:
|
pascal@15368
|
397 .ascii "No 386+."
|
pascal@15368
|
398 .byte 13,10
|
pascal@15368
|
399 .byte 0
|
pascal@15368
|
400 helpmsg:
|
pascal@15368
|
401 .ascii "No help available."
|
pascal@15368
|
402 .byte 13,10
|
pascal@15368
|
403 .byte 0
|
pascal@15368
|
404 #endif
|
pascal@15368
|
405
|
pascal@15368
|
406 /*
|
pascal@15368
|
407 The following header is documented in the Linux source code at
|
pascal@15368
|
408 Documentation/x86/boot.txt
|
pascal@15368
|
409 */
|
pascal@15368
|
410 .org 497
|
pascal@15368
|
411 setup_sects:
|
pascal@15368
|
412 .byte SETUPSECS
|
pascal@15368
|
413 root_flags:
|
pascal@15368
|
414 .word 0
|
pascal@15368
|
415 syssize:
|
pascal@15368
|
416 .long -PREFIXPGH
|
pascal@15368
|
417
|
pascal@15368
|
418 .section ".zinfo.fixup", "a", @progbits /* Compressor fixups */
|
pascal@15368
|
419 .ascii "ADDL"
|
pascal@15368
|
420 .long syssize
|
pascal@15368
|
421 .long 16
|
pascal@15368
|
422 .long 0
|
pascal@15368
|
423 .previous
|
pascal@15368
|
424
|
pascal@15368
|
425 ram_size:
|
pascal@15368
|
426 .word 0
|
pascal@15368
|
427 vid_mode:
|
pascal@15368
|
428 .word 0
|
pascal@15368
|
429 root_dev:
|
pascal@15368
|
430 .word 0
|
pascal@15368
|
431 boot_flag:
|
pascal@15368
|
432 .word 0xAA55
|
pascal@15368
|
433 jump:
|
pascal@15368
|
434 /* Manually specify a two-byte jmp instruction here rather
|
pascal@15368
|
435 * than leaving it up to the assembler. */
|
pascal@15368
|
436 .byte 0xeb
|
pascal@15368
|
437 .byte setup_code - header
|
pascal@15368
|
438 header:
|
pascal@15368
|
439 .byte 'H', 'd', 'r', 'S'
|
pascal@15368
|
440 version:
|
pascal@15368
|
441 .word 0x0207 /* 2.07 */
|
pascal@15368
|
442 realmode_swtch:
|
pascal@15368
|
443 .long 0
|
pascal@15368
|
444 start_sys:
|
pascal@15368
|
445 .word 0
|
pascal@15368
|
446 kernel_version:
|
pascal@15368
|
447 .word 0
|
pascal@15368
|
448 type_of_loader:
|
pascal@15368
|
449 .byte 0
|
pascal@15368
|
450 loadflags:
|
pascal@15368
|
451 .byte 0
|
pascal@15368
|
452 setup_move_size:
|
pascal@15368
|
453 .word 0
|
pascal@15368
|
454 code32_start:
|
pascal@15368
|
455 .long SYSSEG*16
|
pascal@15368
|
456 ramdisk_image:
|
pascal@15368
|
457 .long 0
|
pascal@15368
|
458 ramdisk_size:
|
pascal@15368
|
459 .long 0
|
pascal@15368
|
460 bootsect_kludge:
|
pascal@15368
|
461 .long 0
|
pascal@15368
|
462 heap_end_ptr:
|
pascal@15368
|
463 .word 0
|
pascal@15368
|
464 pad1:
|
pascal@15368
|
465 .word 0
|
pascal@15368
|
466 cmd_line_ptr:
|
pascal@15368
|
467 .long 0
|
pascal@15368
|
468 initrd_addr_max:
|
pascal@15368
|
469 /* We don't use an initrd but some bootloaders (e.g. SYSLINUX) have
|
pascal@15368
|
470 * been known to require this field. Set the value to 2 GB. This
|
pascal@15368
|
471 * value is also used by the Linux kernel. */
|
pascal@15368
|
472 .long 0x7fffffff
|
pascal@15368
|
473 kernel_alignment:
|
pascal@15368
|
474 .long 0
|
pascal@15368
|
475 relocatable_kernel:
|
pascal@15368
|
476 .byte 0
|
pascal@15368
|
477 pad2:
|
pascal@15368
|
478 .byte 0, 0, 0
|
pascal@15368
|
479 cmdline_size:
|
pascal@15368
|
480 .long 0x7ff
|
pascal@15368
|
481 hardware_subarch:
|
pascal@15368
|
482 .long 0
|
pascal@15368
|
483 hardware_subarch_data:
|
pascal@15368
|
484 .byte 0, 0, 0, 0, 0, 0, 0, 0
|
pascal@15368
|
485
|
pascal@15368
|
486 /*
|
pascal@15368
|
487 We don't need to do too much setup.
|
pascal@15368
|
488
|
pascal@15368
|
489 This code gets loaded at SETUPSEG:0. It wants to start
|
pascal@15368
|
490 executing the image that's loaded at SYSSEG:0 and
|
pascal@15368
|
491 whose entry point is SYSSEG:0.
|
pascal@15368
|
492 */
|
pascal@15368
|
493 setup_code:
|
pascal@15368
|
494 movl ramdisk_image, %eax
|
pascal@15368
|
495 orl %eax, %eax
|
pascal@15368
|
496 jnz setup_done
|
pascal@15368
|
497
|
pascal@15368
|
498 movw $default_config, %di
|
pascal@15368
|
499 movw $-1, %bx
|
pascal@15368
|
500
|
pascal@15368
|
501 movw $9, %cx
|
pascal@15368
|
502 1:
|
pascal@15368
|
503 pushw %ax
|
pascal@15368
|
504 loop 1b
|
pascal@15368
|
505 pushw $0x9310
|
pascal@15368
|
506 pushw %ax
|
pascal@15368
|
507 pushw %bx
|
pascal@15368
|
508 pushw %ax
|
pascal@15368
|
509 pushw $0x9300+(INITSEG>>12)
|
pascal@15368
|
510 pushw %di
|
pascal@15368
|
511 pushw %bx
|
pascal@15368
|
512 movb $8, %cl
|
pascal@15368
|
513 1:
|
pascal@15368
|
514 pushw %ax
|
pascal@15368
|
515 loop 1b
|
pascal@15368
|
516 1:
|
pascal@15368
|
517 incw %bx
|
pascal@15368
|
518 cmpb %al, (%bx,%di)
|
pascal@15368
|
519 jne 1b
|
pascal@15368
|
520 movw %bx, ramdisk_size
|
pascal@15368
|
521 movb $0x10, ramdisk_image+2
|
pascal@15368
|
522
|
pascal@15368
|
523 pushw %ss
|
pascal@15368
|
524 popw %es
|
pascal@15368
|
525 movw %sp, %si
|
pascal@15368
|
526 movb $0x87, %ah
|
pascal@15368
|
527 movw $(run_ipxe-default_config)/2+1, %cx
|
pascal@15368
|
528 int $0x15
|
pascal@15368
|
529
|
pascal@15368
|
530 setup_done:
|
pascal@15368
|
531 /* We expect to be contiguous in memory once loaded. The Linux image
|
pascal@15368
|
532 * boot process requires that setup code is loaded separately from
|
pascal@15368
|
533 * "non-real code". Since we don't need any information that's left
|
pascal@15368
|
534 * in the prefix, it doesn't matter: we just have to ensure that
|
pascal@15368
|
535 * %cs:0000 is where the start of the image *would* be.
|
pascal@15368
|
536 */
|
pascal@15368
|
537 ljmp $(SYSSEG-(PREFIXSIZE/16)), $run_ipxe
|
pascal@15368
|
538
|
pascal@15368
|
539 default_config:
|
pascal@15368
|
540
|
pascal@15368
|
541 .org PREFIXSIZE
|
pascal@15368
|
542 /*
|
pascal@15368
|
543 We're now at the beginning of the kernel proper.
|
pascal@15368
|
544 */
|
pascal@15368
|
545 run_ipxe:
|
pascal@15368
|
546 /* Set up stack just below 0x7c00 and clear direction flag */
|
pascal@15368
|
547 xorw %ax, %ax
|
pascal@15368
|
548 movw %ax, %ss
|
pascal@15368
|
549 movw $0x7c00, %sp
|
pascal@15368
|
550 cld
|
pascal@15368
|
551
|
pascal@15368
|
552 /* Retrieve command-line pointer */
|
pascal@15368
|
553 movl %ds:cmd_line_ptr, %edx
|
pascal@15368
|
554 testl %edx, %edx
|
pascal@15368
|
555 jz no_cmd_line
|
pascal@15368
|
556
|
pascal@15368
|
557 /* Set up %es:%di to point to command line */
|
pascal@15368
|
558 movl %edx, %edi
|
pascal@15368
|
559 andl $0xf, %edi
|
pascal@15368
|
560 rorl $4, %edx
|
pascal@15368
|
561 movw %dx, %es
|
pascal@15368
|
562
|
pascal@15368
|
563 /* Find length of command line */
|
pascal@15368
|
564 pushw %di
|
pascal@15368
|
565 movw $0xffff, %cx
|
pascal@15368
|
566 repnz scasb
|
pascal@15368
|
567 notw %cx
|
pascal@15368
|
568 popw %si
|
pascal@15368
|
569
|
pascal@15368
|
570 /* Make space for command line on stack */
|
pascal@15368
|
571 movw %sp, %di
|
pascal@15368
|
572 subw %cx, %di
|
pascal@15368
|
573 andw $~0xf, %di
|
pascal@15368
|
574 movw %di, %sp
|
pascal@15368
|
575
|
pascal@15368
|
576 /* Copy command line to stack */
|
pascal@15368
|
577 pushw %ds
|
pascal@15368
|
578 pushw %es
|
pascal@15368
|
579 popw %ds
|
pascal@15368
|
580 pushw %ss
|
pascal@15368
|
581 popw %es
|
pascal@15368
|
582 rep movsb
|
pascal@15368
|
583 popw %ds
|
pascal@15368
|
584
|
pascal@15368
|
585 /* Store new command-line pointer */
|
pascal@15368
|
586 movzwl %sp, %edx
|
pascal@15368
|
587 no_cmd_line:
|
pascal@15368
|
588
|
pascal@15368
|
589 /* Calculate maximum relocation address */
|
pascal@15368
|
590 movl ramdisk_image, %ebp
|
pascal@15368
|
591 testl %ebp, %ebp
|
pascal@15368
|
592 jnz 1f
|
pascal@15368
|
593 decl %ebp /* Allow arbitrary relocation if no initrd */
|
pascal@15368
|
594 1:
|
pascal@15368
|
595
|
pascal@15368
|
596 /* Install iPXE */
|
pascal@15368
|
597 call alloc_basemem
|
pascal@15368
|
598 xorl %esi, %esi
|
pascal@15368
|
599 xorl %edi, %edi
|
pascal@15368
|
600 call install_prealloc
|
pascal@15368
|
601
|
pascal@15368
|
602 /* Retrieve initrd pointer and size */
|
pascal@15368
|
603 movl ramdisk_image, %ebp
|
pascal@15368
|
604 movl ramdisk_size, %ecx
|
pascal@15368
|
605
|
pascal@15368
|
606 start_ipxe:
|
pascal@15368
|
607 /* Set up real-mode stack */
|
pascal@15368
|
608 movw %bx, %ss
|
pascal@15368
|
609 movw $_estack16, %sp
|
pascal@15368
|
610
|
pascal@15368
|
611 /* Jump to .text16 segment */
|
pascal@15368
|
612 pushw %ax
|
pascal@15368
|
613 pushw $1f
|
pascal@15368
|
614 lret
|
pascal@15368
|
615 .section ".text16", "awx", @progbits
|
pascal@15368
|
616 1:
|
pascal@15368
|
617 /* Set up %ds for access to .data16 */
|
pascal@15368
|
618 movw %bx, %ds
|
pascal@15368
|
619
|
pascal@15368
|
620 /* Store command-line pointer */
|
pascal@15368
|
621 movl %edx, cmdline_phys
|
pascal@15368
|
622
|
pascal@15368
|
623 /* Store initrd pointer and size */
|
pascal@15368
|
624 movl %ebp, initrd_phys
|
pascal@15368
|
625 movl %ecx, initrd_len
|
pascal@15368
|
626
|
pascal@15368
|
627 /* Run iPXE */
|
pascal@15368
|
628 pushl $main
|
pascal@15368
|
629 pushw %cs
|
pascal@15368
|
630 call prot_call
|
pascal@15368
|
631 popl %ecx /* discard */
|
pascal@15368
|
632
|
pascal@15368
|
633 /* Uninstall iPXE */
|
pascal@15368
|
634 call uninstall
|
pascal@15368
|
635
|
pascal@15368
|
636 /* Boot next device */
|
pascal@15368
|
637 int $0x18
|