!!	setup.s		(C) 1991 Linus Torvalds!! setup.s is responsible for getting the system data from the BIOS,! and putting them into the appropriate places in system memory.! both setup.s and system has been loaded by the bootblock.!! This code asks the bios for memory/disk/other parameters, and! puts them in a "safe" place: 0x90000-0x901FF, ie where the! boot-block used to be. It is then up to the protected mode! system to read them from there before the area is overwritten! for buffer-blocks.!! NOTE! These had better be the same as in bootsect.s!INITSEG  = 0x9000	! we move boot here - out of the waySYSSEG   = 0x1000	! system loaded at 0x10000 (65536).SETUPSEG = 0x9020	! this is the current segment.globl begtext, begdata, begbss, endtext, enddata, endbss.textbegtext:.databegdata:.bssbegbss:.textentry startstart:! ok, the read went well so we get current cursor position and save it for! posterity.	mov	ax,#INITSEG	! this is done in bootsect already, but...	mov	ds,ax	mov	ah,#0x03	! read cursor pos	xor	bh,bh	int	0x10		! save it in known place, con_init fetches	mov	[0],dx		! it from 0x90000.! Get memory size (extended mem, kB)	mov	ah,#0x88	int	0x15	mov	[2],ax! Get video-card data:	mov	ah,#0x0f	int	0x10	mov	[4],bx		! bh = display page	mov	[6],ax		! al = video mode, ah = window width! check for EGA/VGA and some config parameters	mov	ah,#0x12	mov	bl,#0x10	int	0x10	mov	[8],ax	mov	[10],bx	mov	[12],cx! Get hd0 data	mov	ax,#0x0000	mov	ds,ax	lds	si,[4*0x41]	mov	ax,#INITSEG	mov	es,ax	mov	di,#0x0080	mov	cx,#0x10	rep	movsb! Get hd1 data	mov	ax,#0x0000	mov	ds,ax	lds	si,[4*0x46]	mov	ax,#INITSEG	mov	es,ax	mov	di,#0x0090	mov	cx,#0x10	rep	movsb! Check that there IS a hd1 :-)	mov	ax,#0x01500	mov	dl,#0x81	int	0x13	jc	no_disk1	cmp	ah,#3	je	is_disk1no_disk1:	mov	ax,#INITSEG	mov	es,ax	mov	di,#0x0090	mov	cx,#0x10	mov	ax,#0x00	rep	stosbis_disk1:! now we want to move to protected mode ...	cli			! no interrupts allowed !! first we move the system to it's rightful place	mov	ax,#0x0000	cld			! 'direction'=0, movs moves forwarddo_move:	mov	es,ax		! destination segment	add	ax,#0x1000	cmp	ax,#0x9000	jz	end_move	mov	ds,ax		! source segment	sub	di,di	sub	si,si	mov 	cx,#0x8000	rep	movsw	jmp	do_move! then we load the segment descriptorsend_move:	mov	ax,#SETUPSEG	! right, forgot this at first. didn't work :-)	mov	ds,ax	lidt	idt_48		! load idt with 0,0	lgdt	gdt_48		! load gdt with whatever appropriate! that was painless, now we enable A20	call	empty_8042	mov	al,#0xD1		! command write	out	#0x64,al	call	empty_8042	mov	al,#0xDF		! A20 on	out	#0x60,al	call	empty_8042! well, that went ok, I hope. Now we have to reprogram the interrupts :-(! we put them right after the intel-reserved hardware interrupts, at! int 0x20-0x2F. There they won't mess up anything. Sadly IBM really! messed this up with the original PC, and they haven't been able to! rectify it afterwards. Thus the bios puts interrupts at 0x08-0x0f,! which is used for the internal hardware interrupts as well. We just! have to reprogram the 8259's, and it isn't fun.	mov	al,#0x11		! initialization sequence	out	#0x20,al		! send it to 8259A-1	.word	0x00eb,0x00eb		! jmp $+2, jmp $+2	out	#0xA0,al		! and to 8259A-2	.word	0x00eb,0x00eb	mov	al,#0x20		! start of hardware int's (0x20)	out	#0x21,al	.word	0x00eb,0x00eb	mov	al,#0x28		! start of hardware int's 2 (0x28)	out	#0xA1,al	.word	0x00eb,0x00eb	mov	al,#0x04		! 8259-1 is master	out	#0x21,al	.word	0x00eb,0x00eb	mov	al,#0x02		! 8259-2 is slave	out	#0xA1,al	.word	0x00eb,0x00eb	mov	al,#0x01		! 8086 mode for both	out	#0x21,al	.word	0x00eb,0x00eb	out	#0xA1,al	.word	0x00eb,0x00eb	mov	al,#0xFF		! mask off all interrupts for now	out	#0x21,al	.word	0x00eb,0x00eb	out	#0xA1,al! well, that certainly wasn't fun :-(. Hopefully it works, and we don't! need no steenking BIOS anyway (except for the initial loading :-).! The BIOS-routine wants lots of unnecessary data, and it's less! "interesting" anyway. This is how REAL programmers do it.!! Well, now's the time to actually move into protected mode. To make! things as simple as possible, we do no register set-up or anything,! we let the gnu-compiled 32-bit programs do that. We just jump to! absolute address 0x00000, in 32-bit protected mode.	mov	ax,#0x0001	! protected mode (PE) bit	lmsw	ax		! This is it!	jmpi	0,8		! jmp offset 0 of segment 8 (cs)! This routine checks that the keyboard command queue is empty! No timeout is used - if this hangs there is something wrong with! the machine, and we probably couldn't proceed anyway.empty_8042:	.word	0x00eb,0x00eb	in	al,#0x64	! 8042 status port	test	al,#2		! is input buffer full?	jnz	empty_8042	! yes - loop	retgdt:	.word	0,0,0,0		! dummy	.word	0x07FF		! 8Mb - limit=2047 (2048*4096=8Mb)	.word	0x0000		! base address=0	.word	0x9A00		! code read/exec	.word	0x00C0		! granularity=4096, 386	.word	0x07FF		! 8Mb - limit=2047 (2048*4096=8Mb)	.word	0x0000		! base address=0	.word	0x9200		! data read/write	.word	0x00C0		! granularity=4096, 386idt_48:	.word	0			! idt limit=0	.word	0,0			! idt base=0Lgdt_48:	.word	0x800		! gdt limit=2048, 256 GDT entries	.word	512+gdt,0x9	! gdt base = 0X9xxxx	.textendtext:.dataenddata:.bssendbss: