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/*
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* Start an Application Processor. This must be placed on a 4KB boundary
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* somewhere in the 1st MB of conventional memory (APBOOTSTRAP). However,
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* due to some shortcuts below it's restricted further to within the 1st
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* 64KB. The AP starts in real-mode, with
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* CS selector set to the startup memory address/16;
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* CS base set to startup memory address;
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* CS limit set to 64KB;
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* CPL and IP set to 0.
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*/
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#include "mem.h"
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#define NOP BYTE $0x90 /* NOP */
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#define LGDT(gdtptr) BYTE $0x0F; /* LGDT */ \
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BYTE $0x01; BYTE $0x16; \
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WORD $gdtptr
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#define FARJUMP16(s, o) BYTE $0xEA; /* far jump to ptr16:16 */ \
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WORD $o; WORD $s; \
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NOP; NOP; NOP
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#define FARJUMP32(s, o) BYTE $0x66; /* far jump to ptr32:16 */ \
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BYTE $0xEA; LONG $o; WORD $s
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#define DELAY BYTE $0xEB; /* JMP .+2 */ \
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BYTE $0x00
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#define INVD BYTE $0x0F; BYTE $0x08
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#define WBINVD BYTE $0x0F; BYTE $0x09
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/*
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* Macros for calculating offsets within the page directory base
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* and page tables. Note that these are assembler-specific hence
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* the '<<2'.
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*/
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#define PDO(a) (((((a))>>22) & 0x03FF)<<2)
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#define PTO(a) (((((a))>>12) & 0x03FF)<<2)
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TEXT apbootstrap(SB), $0
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FARJUMP16(0, _apbootstrap(SB))
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TEXT _apvector(SB), $0 /* address APBOOTSTRAP+0x08 */
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LONG $0
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TEXT _appdb(SB), $0 /* address APBOOTSTRAP+0x0C */
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LONG $0
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TEXT _apapic(SB), $0 /* address APBOOTSTRAP+0x10 */
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LONG $0
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TEXT _apbootstrap(SB), $0 /* address APBOOTSTRAP+0x14 */
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MOVW CS, AX
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MOVW AX, DS /* initialise DS */
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LGDT(gdtptr(SB)) /* load a basic gdt */
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MOVL CR0, AX
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ORL $1, AX
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MOVL AX, CR0 /* turn on protected mode */
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DELAY /* JMP .+2 */
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BYTE $0xB8; WORD $SELECTOR(1, SELGDT, 0)/* MOVW $SELECTOR(1, SELGDT, 0), AX */
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MOVW AX, DS
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MOVW AX, ES
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MOVW AX, FS
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MOVW AX, GS
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MOVW AX, SS
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FARJUMP32(SELECTOR(2, SELGDT, 0), _ap32-KZERO(SB))
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/*
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* For Pentiums and higher, the code that enables paging must come from
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* pages that are identity mapped.
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* To this end double map KZERO at virtual 0 and undo the mapping once virtual
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* nirvana has been obtained.
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*/
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TEXT _ap32(SB), $0
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MOVL _appdb-KZERO(SB), CX /* physical address of PDB */
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MOVL (PDO(KZERO))(CX), DX /* double-map KZERO at 0 */
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MOVL DX, (PDO(0))(CX)
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MOVL CX, CR3 /* load and flush the mmu */
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MOVL CR0, DX
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ORL $0x80010000, DX /* PG|WP */
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ANDL $~0x6000000A, DX /* ~(CD|NW|TS|MP) */
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MOVL $_appg(SB), AX
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MOVL DX, CR0 /* turn on paging */
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JMP* AX
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TEXT _appg(SB), $0
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MOVL CX, AX /* physical address of PDB */
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ORL $KZERO, AX
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MOVL $0, (PDO(0))(AX) /* undo double-map of KZERO at 0 */
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MOVL CX, CR3 /* load and flush the mmu */
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MOVL $(MACHADDR+MACHSIZE-4), SP
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MOVL $0, AX
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PUSHL AX
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POPFL
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MOVL _apapic(SB), AX
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MOVL AX, (SP)
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MOVL _apvector(SB), AX
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CALL* AX
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_aphalt:
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HLT
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JMP _aphalt
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TEXT gdt(SB), $0
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LONG $0x0000; LONG $0
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LONG $0xFFFF; LONG $(SEGG|SEGB|(0xF<<16)|SEGP|SEGPL(0)|SEGDATA|SEGW)
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LONG $0xFFFF; LONG $(SEGG|SEGD|(0xF<<16)|SEGP|SEGPL(0)|SEGEXEC|SEGR)
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TEXT gdtptr(SB), $0
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WORD $(3*8-1)
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LONG $gdt-KZERO(SB)
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