Vol. 3A 9-21
PROCESSOR MANAGEMENT AND INITIALIZATION
207 INC ECX
208 MOV EDX,EAX
209 MOV APP_GDT_ram[EBX].table_linear,EAX
210 ADD EAX,ECX
211 REP MOVS BYTE PTR ES:[EDI],BYTE PTR DS:[ESI]
212
213 ; fixup GDT base in descriptor
214 MOV ECX,EDX
215 MOV [EDX].bas_0_15+GDT_DESC_OFF,CX
216 ROR ECX,16
217 MOV [EDX].bas_16_23+GDT_DESC_OFF,CL
218 MOV [EDX].bas_24_31+GDT_DESC_OFF,CH
219
220 ; copy EPROM IDT to ram at:
221 ; RAM_START+size(STARTUP_DATA)+SIZE (EPROM GDT)
222 MOV ECX, CS_BASE
223 ADD ECX, OFFSET (IDT_EPROM)
224 MOV ESI, [ECX].table_linear
225 MOV EDI,EAX
226 MOVZX ECX, [ECX].table_lim
227 MOV APP_IDT_ram[EBX].table_lim,CX
228 INC ECX
229 MOV APP_IDT_ram[EBX].table_linear,EAX
230 MOV EBX,EAX
231 ADD EAX,ECX
232 REP MOVS BYTE PTR ES:[EDI],BYTE PTR DS:[ESI]
233
234 ; fixup IDT pointer in GDT
235 MOV [EDX].bas_0_15+IDT_DESC_OFF,BX
236 ROR EBX,16
237 MOV [EDX].bas_16_23+IDT_DESC_OFF,BL
238 MOV [EDX].bas_24_31+IDT_DESC_OFF,BH
239
240 ; load GDTR and IDTR
241 MOV EBX,RAM_START
242 DB 66H ; execute a 32 bit LGDT
243 LGDT APP_GDT_ram[EBX]
244 DB 66H ; execute a 32 bit LIDT
245 LIDT APP_IDT_ram[EBX]
246
247 ; move the TSS
248 MOV EDI,EAX
249 MOV EBX,TSS_INDEX*SIZE(DESC)
250 MOV ECX,GDT_DESC_OFF ;build linear address for TSS
251 MOV GS,CX
252 MOV DH,GS:[EBX].bas_24_31
253 MOV DL,GS:[EBX].bas_16_23
254 ROL EDX,16
255 MOV DX,GS:[EBX].bas_0_15
256 MOV ESI,EDX
257 LSL ECX,EBX
258 INC ECX
259 MOV EDX,EAX
260 ADD EAX,ECX