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