From 8eac795166f0db6c1826fd2ab1b4f830b2b72415 Mon Sep 17 00:00:00 2001 From: pumnflqv2 Date: Sun, 26 Jun 2022 21:31:57 +0800 Subject: [PATCH] ADD file via upload --- boot/setup.s | 231 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 231 insertions(+) create mode 100644 boot/setup.s diff --git a/boot/setup.s b/boot/setup.s new file mode 100644 index 0000000..2329d00 --- /dev/null +++ b/boot/setup.s @@ -0,0 +1,231 @@ +! +! 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 way +SYSSEG = 0x1000 ! system loaded at 0x10000 (65536). +SETUPSEG = 0x9020 ! this is the current segment + +.globl begtext, begdata, begbss, endtext, enddata, endbss +.text +begtext: +.data +begdata: +.bss +begbss: +.text + +entry start +start: + +! 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_disk1 +no_disk1: + mov ax,#INITSEG + mov es,ax + mov di,#0x0090 + mov cx,#0x10 + mov ax,#0x00 + rep + stosb +is_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 forward +do_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 descriptors + +end_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 + ret + +gdt: + .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, 386 + +idt_48: + .word 0 ! idt limit=0 + .word 0,0 ! idt base=0L + +gdt_48: + .word 0x800 ! gdt limit=2048, 256 GDT entries + .word 512+gdt,0x9 ! gdt base = 0X9xxxx + +.text +endtext: +.data +enddata: +.bss +endbss: