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https://communities.intel.com/servlet/JiveServlet/downloadBody/5061-102-1-8118/Pentium_SW_Developers_Manual_Vol3_SystemProgramming.pdf
Guckst du Seite 8-23.
8-23
PROCESSOR MANAGEMENT AND INITIALIZATION
153 ; here with a near JMP generated by the builder. This
154 ; label must be in the top 64K of linear memory.
155
156 PUBLIC STARTUP
157 STARTUP:
158
159 ; DS,ES address the bottom 64K of flat linear memory
160 ASSUME DS:STARTUP_DATA, ES:STARTUP_DATA
161 ; See Figure 8-4
162 ; load GDTR with temporary GDT
163 LEA EBX,TEMP_GDT ; build the TEMP_GDT in low ram,
164 MOV DWORD PTR [EBX],0 ; where we can address
165 MOV DWORD PTR [EBX]+4,0
166 MOV DWORD PTR [EBX]+8, LINEAR_PROTO_LO
167 MOV DWORD PTR [EBX]+12, LINEAR_PROTO_HI
168 MOV TEMP_GDT_scratch.table_linear,EBX
169 MOV TEMP_GDT_scratch.table_lim,15
170
171 DB 66H ; execute a 32 bit LGDT
172 LGDT TEMP_GDT_scratch
173
174 ; enter protected mode
175 MOV EBX,CR0
176 OR EBX,PE_BIT
177 MOV CR0,EBX
178
179 ; clear prefetch queue
180 JMP CLEAR_LABEL
181 CLEAR_LABEL:
182
183 ; make DS and ES address 4G of linear memory
184 MOV CX,LINEAR_SEL
185 MOV DS,CX
186 MOV ES,CX
187
188 ; do board specific initialization
189 ;
190 ;
191 ; ......
192 ;
193
194
195 ; See Figure 8-5
196 ; copy EPROM GDT to ram at:
197 ; RAM_START + size (STARTUP_DATA)
198 MOV EAX,RAM_START
