xref: /inferno-os/os/boot/pc/mem.h (revision 8a8c2d742b51525f66c2210e3c8a251de10022ff)

/*
 * Memory and machine-specific definitions.  Used in C and assembler.
 */

/*
 * Sizes
 */
#define	BI2BY		8			/* bits per byte */
#define	BI2WD		32			/* bits per word */
#define	BY2WD		4			/* bytes per word */
#define	BY2PG		4096			/* bytes per page */
#define	WD2PG		(BY2PG/BY2WD)		/* words per page */
#define	PGSHIFT		12			/* log(BY2PG) */
#define	PGROUND(s)	(((s)+(BY2PG-1))&~(BY2PG-1))

#define	MAXMACH		1			/* max # cpus system can run */

/*
 * Time
 */
#define	HZ		(100)				/* clock frequency */
#define	MS2HZ		(1000/HZ)			/* millisec per clock tick */
#define	TK2SEC(t)	((t)/HZ)			/* ticks to seconds */
#define	TK2MS(x)	((x)*(1000/HZ))
#define	MS2TK(t)	((((ulong)(t))*HZ)/1000)	/* milliseconds to ticks */

/*
 * Fundamental addresses
 */
#define IDTADDR		0x80000800		/* idt */
#define APBOOTSTRAP	0x80001000		/* AP bootstrap code */
#define CONFADDR	0x80001200		/* info passed from boot loader */
#define CPU0PDB		0x80002000		/* bootstrap processor PDB */
#define CPU0PTE		0x80003000		/* bootstrap processor PTE's for 0-4MB */
#define MACHADDR	0x80004000		/* as seen by current processor */
#define CPU0MACH	0x80005000		/* Mach for bootstrap processor */
#define BIOSXCHG	0x80006000		/* To exchange data with the BIOS */
#define	MACHSIZE	(BY2PG*8)		/* stack size */

/*
 *  Address spaces
 *
 *  Kernel is at 2GB-4GB
 */
#define	KZERO		0x80000000		/* base of kernel address space */
#define	KTZERO		KZERO			/* first address in kernel text */
#define ROMBIOS		(KZERO|0xF0000)

/*
 *  known 80386 segments (in GDT) and their selectors
 */
#define	NULLSEG	0	/* null segment */
#define	KDSEG	1	/* kernel data/stack */
#define	KESEG	2	/* kernel executable */
#define	UDSEG	3	/* user data/stack */
#define	UESEG	4	/* user executable */
#define	SYSGATE	5	/* system call gate */
#define TSSSEG	6	/* task segment */

#define SELGDT	(0<<3)	/* selector is in gdt */
#define	SELLDT	(1<<3)	/* selector is in ldt */

#define SELECTOR(i, t, p)	(((i)<<3) | (t) | (p))

#define NULLSEL	SELECTOR(NULLSEG, SELGDT, 0)
#define KESEL	SELECTOR(KESEG, SELGDT, 0)
#define KDSEL	SELECTOR(KDSEG, SELGDT, 0)
#define UESEL	SELECTOR(UESEG, SELGDT, 3)
#define UDSEL	SELECTOR(UDSEG, SELGDT, 3)
#define TSSSEL	SELECTOR(TSSSEG, SELGDT, 0)

/*
 *  fields in segment descriptors
 */
#define SEGDATA	(0x10<<8)	/* data/stack segment */
#define SEGEXEC	(0x18<<8)	/* executable segment */
#define	SEGTSS	(0x9<<8)	/* TSS segment */
#define SEGCG	(0x0C<<8)	/* call gate */
#define	SEGIG	(0x0E<<8)	/* interrupt gate */
#define SEGTG	(0x0F<<8)	/* task gate */
#define SEGTYPE	(0x1F<<8)

#define SEGP	(1<<15)		/* segment present */
#define SEGPL(x) ((x)<<13)	/* priority level */
#define SEGB	(1<<22)		/* granularity 1==4k (for expand-down) */
#define SEGG	(1<<23)		/* granularity 1==4k (for other) */
#define SEGE	(1<<10)		/* expand down */
#define SEGW	(1<<9)		/* writable (for data/stack) */
#define	SEGR	(1<<9)		/* readable (for code) */
#define SEGD	(1<<22)		/* default 1==32bit (for code) */

/*
 *  virtual MMU
 */
#define PTEMAPMEM	(1024*1024)	/* ??? */
#define SEGMAPSIZE	16		/* ??? */
#define	PTEPERTAB	(PTEMAPMEM/BY2PG)	/* ??? */
#define PPN(x)		((x)&~(BY2PG-1))

/*
 *  physical MMU
 */
#define	PTEVALID	(1<<0)
#define	PTEUNCACHED	0		/* everything is uncached */
#define	PTEWRITE	(1<<1)
#define	PTERONLY	(0<<1)
#define	PTEKERNEL	(0<<2)
#define	PTEUSER		(1<<2)
#define	PTESIZE		(1<<7)

/*
 *  flag register bits that we care about
 */
#define IFLAG	0x200