// Rom layout and bios assembler to C interface. // // Copyright (C) 2008 Kevin O'Connor // Copyright (C) 2002 MandrakeSoft S.A. // // This file may be distributed under the terms of the GNU GPLv3 license. #include "config.h" #define PROTECTED_MODE_CS (2 << 3) // 0x10 #define PROTECTED_MODE_DS (3 << 3) // 0x18 #define REAL_MODE_CS (4 << 3) // 0x20 #define REAL_MODE_DS (5 << 3) // 0x28 .code16gcc /**************************************************************** * Include of 16bit C code ****************************************************************/ .globl bios16c_start, bios16c_end bios16c_start: .include "out/blob.proc.16.s" .text bios16c_end: /**************************************************************** * POST handler ****************************************************************/ // Macro to reset the 16bit stack // Clobbers %ax .macro RESET_STACK xorw %ax, %ax movw %ax, %ss movl $ CONFIG_STACK_OFFSET , %esp .endm .org 0xe05b .globl post16 post16: // init the stack pointer RESET_STACK // Set entry point of rombios32 code - the actual address // is altered later in the build process. .globl set_entry32 set_entry32: pushl $0xf0000000 cld // Fall through to transition32 function below /**************************************************************** * Call trampolines ****************************************************************/ // Place CPU into 32bit mode from 16bit mode. // Clobbers: %eax, flags, stack registers, cr0, idt/gdt transition32: // Disable irqs cli // enable a20 inb $0x92, %al orb $0x02, %al outb %al, $0x92 // Set segment descriptors lidt %cs:pmode_IDT_info lgdt %cs:rombios32_gdt_48 // set PE bit in CR0 movl %cr0, %eax orb $0x01, %al movl %eax, %cr0 // start protected mode code // ljmpl $PROTECTED_MODE_CS, $(1f | 0xf0000) .word 0xea66, 1f, 0x000f, PROTECTED_MODE_CS .code32 1: // init data segments movl $PROTECTED_MODE_DS, %eax movw %ax, %ds movw %ax, %es movw %ax, %ss xorl %eax, %eax movw %ax, %fs movw %ax, %gs retl // Call a 16bit function from 32bit mode. // %eax = address of struct bregs // Clobbers: all gp registers, flags, stack registers, cr0, idt/gdt .globl __call16_from32 __call16_from32: pushl %eax // Jump to 16bit mode ljmp $REAL_MODE_CS, $1f .code16gcc 1: // restore data segment limits to 0xffff movw $REAL_MODE_DS, %ax movw %ax, %ds movw %ax, %es movw %ax, %ss movw %ax, %fs movw %ax, %gs // reset PE bit in CR0 movl %cr0, %eax andb $0xfe, %al movl %eax, %cr0 // far jump to flush CPU queue after transition to real mode ljmpw $0xf000, $2f 2: // restore IDT to normal real-mode defaults lidt %cs:rmode_IDT_info // Clear segment registers xorw %ax, %ax movw %ax, %fs movw %ax, %gs movw %ax, %es movw %ax, %ds movw %ax, %ss // Assume stack is in segment 0 popl %eax pushl $transition32 // Fall through to __call16 // Call a 16bit function from 16bit mode with a specified cpu register state // %eax = address of struct bregs // Clobbers: all gp registers, es .globl __call16 __call16: // Save eax pushl %eax // Setup for iretw call pushw $0xf000 pushw $1f // return point pushw 0x28(%eax) // flags pushl 0x24(%eax) // CS:IP // Load calling registers. movl 0x04(%eax), %edi movl 0x08(%eax), %esi movl 0x0c(%eax), %ebp movl 0x14(%eax), %ebx movl 0x18(%eax), %edx movl 0x1c(%eax), %ecx movw 0x02(%eax), %es // XXX - should load %ds too movl 0x20(%eax), %eax // Invoke call iretw // XXX - just do a lcalll 1: // Store flags, eax, ecx pushfw pushl %eax movl 0x06(%esp), %eax movl %ecx, %ss:0x1c(%eax) // Save %ecx movw %ss, %cx movw %cx, %ds // Restore %ds == %ss popl %ecx movl %ecx, 0x20(%eax) // Save %eax popw %cx movw %cx, 0x28(%eax) // Save flags // Store remaining registers movw %es, 0x02(%eax) movl %edi, 0x04(%eax) movl %esi, 0x08(%eax) movl %ebp, 0x0c(%eax) movl %ebx, 0x14(%eax) movl %edx, 0x18(%eax) // Remove %eax popl %eax cld retl /**************************************************************** * GDT and IDT tables ****************************************************************/ // Protected mode IDT descriptor // // I just make the limit 0, so the machine will shutdown // if an exception occurs during protected mode memory // transfers. // // Set base to f0000 to correspond to beginning of BIOS, // in case I actually define an IDT later // Set limit to 0 pmode_IDT_info: .word 0x0000 // limit 15:00 .long 0xf0000 // base 16:47 // Real mode IDT descriptor // // Set to typical real-mode values. // base = 000000 // limit = 03ff rmode_IDT_info: .word 0x03ff // limit 15:00 .long 0 // base 16:47 rombios32_gdt_48: .word 0x30 .word rombios32_gdt .word 0x000f .balign 8 rombios32_gdt: .word 0, 0, 0, 0 .word 0, 0, 0, 0 // 32 bit flat code segment (PROTECTED_MODE_CS) .word 0xffff, 0, 0x9b00, 0x00cf // 32 bit flat data segment (PROTECTED_MODE_DS) .word 0xffff, 0, 0x9300, 0x00cf // 16 bit code segment base=0xf0000 limit=0xffff (REAL_MODE_CS) .word 0xffff, 0, 0x9b0f, 0x0000 // 16 bit data segment base=0x0 limit=0xffff (REAL_MODE_DS) .word 0xffff, 0, 0x9300, 0x0000 /**************************************************************** * Interrupt entry points ****************************************************************/ // Call a C function - this does the minimal work necessary to // call into C. It sets up %ds, backs up %es, and backs up // those registers that are call clobbered by the C compiler. .macro ENTRY cfunc cld pushl %eax pushl %ecx pushl %edx pushw %es pushw %ds movw %ss, %ax movw %ax, %ds calll \cfunc popw %ds popw %es popl %edx popl %ecx popl %eax .endm // Call a C function with current register list as an // argument. This backs up the registers and sets %eax // to point to the backup. On return, the registers are // restored from the structur. .macro ENTRY_ARG cfunc cld pushal pushw %es pushw %ds movw %ss, %ax movw %ax, %ds movzwl %sp, %esp movl %esp, %eax calll \cfunc popw %ds popw %es popal .endm // Define an entry point for an interrupt (no args passed). .macro IRQ_ENTRY num .globl entry_\num entry_\num : cli // In case something far-calls instead of using "int" ENTRY handle_\num iretw .endm // Define an entry point for an interrupt (can read/modify args). .macro IRQ_ENTRY_ARG num .globl entry_\num entry_\num : cli // In case something far-calls instead of using "int" ENTRY_ARG handle_\num iretw .endm // APM trampolines .globl apm16protected_entry apm16protected_entry: pushfw // save flags pushl %eax // dummy ENTRY_ARG handle_1553 addw $4, %sp // pop dummy popfw // restore flags lretw .code32 .globl apm32protected_entry apm32protected_entry: pushfw // save flags pushw %cs // Setup for long jump to 16bitmode incw (%esp) pushw 1f lcallw *(%esp) addl $4, %esp // pop call address popfw lretl .code16gcc 1: // 16bit entry point for apm32 code. ENTRY_ARG handle_1553 lretw .org 0xe2c3 IRQ_ENTRY nmi IRQ_ENTRY_ARG 13 IRQ_ENTRY_ARG 12 IRQ_ENTRY_ARG 11 IRQ_ENTRY 76 IRQ_ENTRY 1c IRQ_ENTRY 70 IRQ_ENTRY 74 IRQ_ENTRY 75 .org 0xe3fe jmp entry_13 .org 0xe401 // XXX - Fixed Disk Parameter Table .org 0xe6f2 jmp entry_19 .org 0xe6f5 .include "out/cbt.proc.16.s" .text .org 0xe729 // XXX - Baud Rate Generator Table .org 0xe739 IRQ_ENTRY_ARG 14 // int 18/19 are special - they reset the stack and do not return. .globl entry_19 entry_19: RESET_STACK ENTRY handle_19 .globl entry_18 entry_18: RESET_STACK ENTRY handle_18 // IRQ trampolines .macro IRQ_TRAMPOLINE num .globl irq_trampoline_0x\num irq_trampoline_0x\num : int $0x\num lretw .endm IRQ_TRAMPOLINE 02 IRQ_TRAMPOLINE 10 IRQ_TRAMPOLINE 13 IRQ_TRAMPOLINE 15 IRQ_TRAMPOLINE 18 IRQ_TRAMPOLINE 19 IRQ_TRAMPOLINE 1c IRQ_TRAMPOLINE 4a .org 0xe82e IRQ_ENTRY_ARG 16 .org 0xe987 IRQ_ENTRY 09 .org 0xec59 IRQ_ENTRY_ARG 40 .org 0xef57 IRQ_ENTRY 0e .org 0xefc7 .include "out/floppy_dbt.proc.16.s" .text .org 0xefd2 IRQ_ENTRY_ARG 17 .org 0xf045 // XXX int 10 iretw .org 0xf065 IRQ_ENTRY_ARG 10 .org 0xf0a4 // XXX int 1D iretw .globl freespace2_start, freespace2_end freespace2_start: .org 0xf841 freespace2_end: jmp entry_12 .org 0xf84d jmp entry_11 .org 0xf859 IRQ_ENTRY_ARG 15 .org 0xfa6e .include "out/font.proc.16.s" .text .org 0xfe6e IRQ_ENTRY_ARG 1a .org 0xfea5 IRQ_ENTRY 08 .org 0xfef3 // XXX - Initial Interrupt Vector Offsets Loaded by POST .org 0xff00 // XXX - BIOS_COPYRIGHT_STRING .ascii "(c) 2002 MandrakeSoft S.A. Written by Kevin Lawton & the Bochs team." .org 0xff53 .globl dummy_iret_handler dummy_iret_handler: iretw .org 0xff54 IRQ_ENTRY_ARG 05 .org 0xfff0 // Power-up Entry Point ljmpw $0xf000, $post16 .org 0xfff5 // BIOS build date .ascii "06/23/99" .org 0xfffe .byte CONFIG_MODEL_ID .byte 0x00 .end