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2 | pj | 1 | /* Project: OSLib |
2 | * Description: The OS Construction Kit |
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3 | * Date: 1.6.2000 |
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4 | * Idea by: Luca Abeni & Gerardo Lamastra |
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5 | * |
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6 | * OSLib is an SO project aimed at developing a common, easy-to-use |
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7 | * low-level infrastructure for developing OS kernels and Embedded |
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8 | * Applications; it partially derives from the HARTIK project but it |
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9 | * currently is independently developed. |
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10 | * |
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11 | * OSLib is distributed under GPL License, and some of its code has |
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12 | * been derived from the Linux kernel source; also some important |
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13 | * ideas come from studying the DJGPP go32 extender. |
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14 | * |
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15 | * We acknowledge the Linux Community, Free Software Foundation, |
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16 | * D.J. Delorie and all the other developers who believe in the |
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17 | * freedom of software and ideas. |
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18 | * |
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19 | * For legalese, check out the included GPL license. |
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20 | */ |
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21 | |||
22 | /* The first things to do when an OSLib application starts : */ |
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23 | /* Set up segment registers & stack; then execute startup code */ |
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24 | /* When the application returns the gate-jmp make us return to */ |
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25 | /* RM through X interface! */ |
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26 | |||
27 | /* Use X standard GDT selectors */ |
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28 | #include <ll/i386/sel.h> |
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29 | #include <ll/i386/linkage.h> |
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30 | #include <ll/i386/defs.h> |
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31 | #include <ll/i386/mb-hdr.h> |
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32 | |||
33 | /* #define __DEBUG__ */ |
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34 | |||
35 | #ifdef __LINUX__ /* ELF mode */ |
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36 | #define MULTIBOOT_FLAGS (MULTIBOOT_MEMORY_INFO) |
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37 | #else /* else it is COFF! */ |
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38 | #define MULTIBOOT_FLAGS (MULTIBOOT_MEMORY_INFO | MULTIBOOT_AOUT_KLUDGE) |
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39 | #endif |
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40 | |||
41 | .extern SYMBOL_NAME(_startup) |
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42 | .extern SYMBOL_NAME(_stkbase) |
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43 | .extern SYMBOL_NAME(_stktop) |
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44 | |||
45 | .extern SYMBOL_NAME(halt) |
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46 | |||
47 | .data |
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48 | |||
49 | ASMFILE(X0) |
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50 | |||
51 | .globl SYMBOL_NAME(IDT) |
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52 | .globl SYMBOL_NAME(GDT_base) |
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53 | .globl SYMBOL_NAME(mb_signature) |
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54 | .globl SYMBOL_NAME(mbi) |
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55 | |||
56 | /* GDT Definition */ |
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57 | GDT: |
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58 | .word 0,0,0,0 /* X_NULL_SEL */ |
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59 | .word 0,0,0,0 /* X_DATA16_SEL */ |
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60 | .word 0,0,0,0 /* X_CODE16_SEL */ |
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61 | .word 0,0,0,0 /* X_CODE32_SEL */ |
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62 | /* X_RM_BACK_GATE */ |
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63 | rmBckGateFix1: /* X_FLATCODE_SEL */ |
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64 | .word 0 |
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65 | .word X_FLATCODE_SEL |
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66 | .word 0x8C00 |
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67 | rmBckGateFix2: |
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68 | .word 0 |
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69 | |||
70 | .word 0,0,0,0 /* X_PM_BACK_GATE */ |
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71 | .word 0xFFFF /* X_FLATDATA_SEL */ |
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72 | .word 0 |
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73 | .word 0x9200 |
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74 | .word 0x00CF |
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75 | .word 0xFFFF /* X_FLATCODE_SEL */ |
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76 | .word 0 |
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77 | .word 0x9A00 |
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78 | .word 0x00CF |
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79 | .word 0,0,0,0 /* X_CALLBIOS_SEL */ |
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80 | .word 0,0,0,0 /* X_CALLBIOS_GATE */ |
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81 | .word 0,0,0,0 /* X_VM86_TSS */ |
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82 | .word 0,0,0,0 /* X_MAIN_TSS */ |
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83 | .fill 256 - 12,8,0 |
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84 | |||
85 | GDT_descr: |
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86 | .word 256*8-1 |
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87 | SYMBOL_NAME_LABEL(GDT_base) |
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88 | .long GDT |
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89 | |||
90 | IDT_descr: |
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91 | .word 256*8-1 # idt contains 256 entries |
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92 | .long SYMBOL_NAME(IDT) |
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93 | |||
94 | /* MultiBoot Data Stuff definition */ |
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95 | SYMBOL_NAME_LABEL(mb_signature) .long 0 |
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96 | SYMBOL_NAME_LABEL(mbi) .long 0 |
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97 | |||
98 | .bss /* This MUST be in the BSS !!! */ |
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99 | /* IDT definition */ |
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100 | SYMBOL_NAME_LABEL(IDT) |
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101 | .fill 256,8,0 # idt is uninitialized |
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102 | |||
103 | /* Protected mode stack */ |
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104 | base: |
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105 | .space 8192,0 |
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106 | tos: |
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107 | |||
108 | .text |
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109 | .globl SYMBOL_NAME(_start) |
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110 | .globl SYMBOL_NAME(__exit) |
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111 | /*.globl SYMBOL_NAME(start)*/ |
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112 | .globl start |
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113 | |||
114 | SYMBOL_NAME_LABEL(_start) |
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115 | /*SYMBOL_NAME_LABEL(start)*/ |
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116 | start: |
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117 | .align 8 |
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118 | /*start:*/ |
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119 | jmp boot_entry |
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120 | /* |
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121 | Here we go with the multiboot header... |
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122 | --------------------------------------- |
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123 | */ |
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124 | .align 8 |
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125 | boot_hdr: |
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126 | .align 8 |
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127 | .long MULTIBOOT_MAGIC |
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128 | .long MULTIBOOT_FLAGS |
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129 | /* Checksum */ |
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130 | .long -(MULTIBOOT_MAGIC+MULTIBOOT_FLAGS) |
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131 | #ifndef __LINUX__ /* COFF mode */ |
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132 | .long boot_hdr |
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133 | /* .long SYMBOL_NAME(start)*/ |
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134 | .long start |
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135 | .long _edata |
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136 | .long _end |
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137 | .long boot_entry |
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138 | #endif |
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139 | |||
140 | boot_entry: /* Just a brief debug check */ |
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141 | #ifdef __DEBUG__ |
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142 | /* A Brown 1 should appear... */ |
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143 | movl $0xB8000,%edi |
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144 | addl $158,%edi |
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145 | movb $'1',%gs:0(%edi) |
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146 | incl %edi |
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147 | movb $6,%gs:0(%edi) |
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148 | #endif |
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149 | |||
150 | /* |
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151 | * Hopefully if it gets here, CS & DS are |
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152 | * Correctly set for FLAT LINEAR mode |
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153 | */ |
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154 | /* Test if GDT is usable */ |
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155 | movl %gs:0(%ebx),%ecx |
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40 | pj | 156 | andl $0x0200,%ecx /* MB_INFO_BOOT_LOADER_NAME */ |
2 | pj | 157 | movl $0xB8000,%edi |
158 | addl $150,%edi |
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159 | movb $'1',%gs:0(%edi) |
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160 | incl %edi |
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161 | movb $6,%gs:0(%edi) |
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40 | pj | 162 | jz GDT_is_not_OK |
2 | pj | 163 | incl %edi |
164 | movb $'2',%gs:0(%edi) |
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165 | incl %edi |
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166 | movb $6,%gs:0(%edi) |
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167 | |||
40 | pj | 168 | movl %gs:64(%ebx), %ebp /* Name Address... */ |
169 | cmpb $'X', %gs:0(%ebp) |
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170 | je GDT_is_OK |
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171 | GDT_is_not_OK: |
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172 | /* |
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173 | * Fix the X_RM_BACK_GATE with the address of halt() |
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174 | */ |
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175 | |||
176 | /* Now I test if the check mechanism is OK... */ |
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2 | pj | 177 | movl $SYMBOL_NAME(halt),%eax |
178 | movw %ax,%gs:rmBckGateFix1 |
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179 | shrl $16,%eax |
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180 | movw %ax,%gs:rmBckGateFix2 |
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181 | |||
182 | /* Load GDT, using the predefined assignment! */ |
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183 | lgdt GDT_descr |
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184 | movl $0xB8000,%edi |
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185 | addl $146,%edi |
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186 | movb $'0',%gs:0(%edi) |
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187 | incl %edi |
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188 | movb $6,%gs:0(%edi) |
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189 | |||
190 | GDT_is_OK: movw $(X_FLATDATA_SEL),%ax |
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191 | movw %ax,%ds |
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192 | movw %ax,%es |
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193 | movw %ax,%ss |
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194 | movw %ax,%fs |
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195 | movw %ax,%gs |
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196 | movl $tos,%esp |
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197 | movl $base,SYMBOL_NAME(_stkbase) |
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198 | movl $tos,SYMBOL_NAME(_stktop) |
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199 | |||
200 | /* Store the MULTIBOOT informations */ |
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201 | movl %eax,SYMBOL_NAME(mb_signature) |
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202 | movl %ebx,SYMBOL_NAME(mbi) |
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203 | |||
204 | /* Store the X passed GDT address! |
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205 | * If GDT is not available is a dummy instruction! |
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206 | */ |
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207 | sgdt GDT_descr |
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208 | |||
209 | /* Now probably is the case to load CS... */ |
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210 | ljmp $X_FLATCODE_SEL, $load_cs |
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211 | |||
212 | load_cs: |
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213 | /* Load IDT */ |
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214 | lidt IDT_descr |
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215 | |||
216 | cld |
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217 | call SYMBOL_NAME(_startup) |
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218 | |||
219 | /* Well I hope when I reach this |
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220 | The X_RM_BACK_GATE has been setup correctly |
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221 | even if the kernel has not been loaded through X! |
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222 | */ |
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223 | .byte 0x0EA /* Direct gate jmp */ |
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224 | .long 0 |
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225 | .word X_RM_BACK_GATE |
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226 | |||
227 | /* Simple function to terminate PM application */ |
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228 | |||
229 | /* void __exit(int code) */ |
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230 | |||
231 | SYMBOL_NAME_LABEL(__exit) |
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232 | pushl %ebp |
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233 | movl %esp,%ebp |
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234 | movl 8(%ebp),%eax |
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235 | .byte 0x0ea /* Direct gate jmp */ |
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236 | .long 0 |
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237 | .word X_RM_BACK_GATE |