diff options
Diffstat (limited to 'boot/mbr.asm')
| -rw-r--r-- | boot/mbr.asm | 171 |
1 files changed, 20 insertions, 151 deletions
diff --git a/boot/mbr.asm b/boot/mbr.asm index a04b759..a6dc876 100644 --- a/boot/mbr.asm +++ b/boot/mbr.asm @@ -5,13 +5,13 @@ ; Copyright 2014 M.Idziorek <m.i@gmx.at> ; ; we have just been loaded by the BIOS and are in 16-bits real mode! +; ; THIS IS THE CENTRAL FILE OF THE BOOTLOADER, after we finished we ; are inside the C kernel! ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;we want 16-bit instructions, before we switch to 32-bit protected mode. -[bits 16] ;define origin of boot record in memory: 0x7c00 ;this is where the BIOS per definition will put the first @@ -22,13 +22,12 @@ ;define where we will load our kernel into memory KERNEL_OFFSET equ 0x1000 +[bits 16] jmp boot_16 ;start boot process -;Global Data -INT_COUNT: - db 0 +;SOME Global Data, mainly strings STR_VERSION: - db "_<-Fool-Loader~0.0.8~",0 + db "_<-Fool-Loader~0.0.13~",0 STR_PROT: db "Entered 32-bit Protected Mode.",0 STR_LOADED: @@ -36,45 +35,6 @@ STR_LOADED: BOOT_DRIVE: db 0 -[bits 32] -; default interrupt handler -interrupt: - - mov al, 0xA0 ; set bit 4 of OCW 1 - out 0xA0, al ; write to primary PIC command register - - mov al, 0x20 ; set bit 4 of OCW 2 - out 0x20, al ; write to primary PIC command register - - iret - - -;handle keyboard interrupt -interrupt2: - - -; mov eax,[INT_COUNT] -; inc eax -; mov [INT_COUNT],eax - - in al,0x60 - mov [INT_COUNT],al - -; call KERNEL_OFFSET+(idt_end-idt_start)+1 ;jump into our Kernel it - - ; will follow our - ; interrupt table - - ; out 0x60,al - - - mov al, 0x20 ; set bit 4 of OCW 2 - out 0x20, al ; write to primary PIC command register - - iret - -;;;;; - ;lets put our temporary GDT (Global Descriptor Table) here %include "boot/GDT.asm" @@ -87,6 +47,9 @@ interrupt2: ;include our routines for switching to 32-bit protected mode %include "boot/pm.asm" +;pic mapping +%include "boot/pic.asm" + ;;;;;;;; BOOT 16-bit real ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;lets start @@ -110,16 +73,18 @@ boot_16: mov dl, [BOOT_DRIVE] call disk_load + ;print info message that kernel was loaded mov bx, STR_LOADED call print_string - ;lets enter Protected mode! + ;finally lets enter Protected mode!!! call switch_to_pm ;;;;;;;; BOOT 32-bit protected mode;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; [bits 32] boot_32_pm: + ;print info message that we are in protected mode! mov ecx,160 mov ebx,STR_PROT call print_string_pm @@ -130,118 +95,22 @@ boot_32_pm: mov al, 0xdd ; command 0xdd: enable a20 out 0x64, al ; send command to controller - ; lidt [idt_descriptor] ;load descriptor table! + ;pic setup + call pic_setup + + + call KERNEL_OFFSET ;jump into our Kernel it - ;pollkb example -; pollkb: -; mov cx,320 -; mov ax,0 -; in al,0x60 -; mov dx,ax -; call print_hex_pm -; jmp pollkb -; - ;mov al,11111101b - ;out 0x61, al - - - ; sti ;enable interrupts - -;************************************************************************ -; Map the 8259A PIC to use interrupts 32-47 within our interrupt table -;************************************************************************ - -%define ICW_1 0x11 ; 00010001 binary. Enables initialization mode and we are sending ICW 4 - -%define PIC_1_CTRL 0x20 ; Primary PIC control register -%define PIC_2_CTRL 0xA0 ; Secondary PIC control register - -%define PIC_1_DATA 0x21 ; Primary PIC data register -%define PIC_2_DATA 0xA1 ; Secondary PIC data register - -%define IRQ_0 0x20 ; IRQs 0-7 mapped to use interrupts 0x20-0x27 -%define IRQ_8 0x28 ; IRQs 8-15 mapped to use interrupts 0x28-0x36 - -MapPIC: - -; Send ICW 1 - Begin initialization ------------------------- - - ; Setup to initialize the primary PIC. Send ICW 1 - - mov al, ICW_1 - out PIC_1_CTRL, al - -; Send ICW 2 - Map IRQ base interrupt numbers --------------- - - ; Remember that we have 2 PICs. Because we are cascading with this second PIC, send ICW 1 to second PIC command register - - out PIC_2_CTRL, al - - ; send ICW 2 to primary PIC - - mov al, IRQ_0 - out PIC_1_DATA, al - - ; send ICW 2 to secondary controller - - mov al, IRQ_8 - out PIC_2_DATA, al - -; Send ICW 3 - Set the IR line to connect both PICs --------- - - ; Send ICW 3 to primary PIC - - mov al, 0x4 ; 0x04 => 0100, second bit (IR line 2) - out PIC_1_DATA, al ; write to data register of primary PIC - - ; Send ICW 3 to secondary PIC - - mov al, 0x2 ; 010=> IR line 2 - out PIC_2_DATA, al ; write to data register of secondary PIC - -; Send ICW 4 - Set x86 mode -------------------------------- - - mov al, 1 ; bit 0 enables 80x86 mode - - ; send ICW 4 to both primary and secondary PICs - - out PIC_1_DATA, al - out PIC_2_DATA, al - -; All done. Null out the data registers - - mov al, 0 - out PIC_1_DATA, al - out PIC_2_DATA, al - - ;mask -in al, 0x21 ; read in the primary PIC Interrupt Mask Register (IMR) -and al, 0x00 ; 0xEF => 11101111b. This sets the IRQ4 bit (Bit 5) in AL -out 0x21, al ; write the value back into IMR - - -in al, 0xA1 ; read in the primary PIC Interrupt Mask Register (IMR) -and al, 0x00 ; 0xEF => 11101111b. This sets the IRQ4 bit (Bit 5) in AL -out 0xA1, al ; write the value back into IMR - - - - call KERNEL_OFFSET;+(idt_end-idt_start) ;jump into our Kernel it - ; will follow our - ; interrupt table ;idt_descriptor: ; dw idt_end-idt_start-1 ; dd KERNEL_OFFSET - - ;;;; DEBUGGING STUFF -times 8 db '@' -dw interrupt -times 8 db '@' -dw interrupt2 -times 8 db '@' - +;times 8 db '@' +;dw interrupt +;times 8 db '@' +;dw interrupt2 +;times 8 db '@' ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |