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/* Project: OSLib
* Description: The OS Construction Kit
* Date: 1.6.2000
* Idea by: Luca Abeni & Gerardo Lamastra
*
* OSLib is an SO project aimed at developing a common, easy-to-use
* low-level infrastructure for developing OS kernels and Embedded
* Applications; it partially derives from the HARTIK project but it
* currently is independently developed.
*
* OSLib is distributed under GPL License, and some of its code has
* been derived from the Linux kernel source; also some important
* ideas come from studying the DJGPP go32 extender.
*
* We acknowledge the Linux Community, Free Software Foundation,
* D.J. Delorie and all the other developers who believe in the
* freedom of software and ideas.
*
* For legalese, check out the included GPL license.
*/
/* The first things to do when an OSLib application starts : */
/* Set up segment registers & stack; then execute startup code */
/* When the application returns the gate-jmp make us return to */
/* RM through X interface! */
/* Use X standard GDT selectors */
#include <ll/i386/sel.h>
#include <ll/i386/linkage.h>
#include <ll/i386/defs.h>
#include <ll/i386/mb-hdr.h>
/* #define __DEBUG__ */
#ifdef __LINUX__ /* ELF mode */
#define MULTIBOOT_FLAGS (MULTIBOOT_MEMORY_INFO)
#else /* else it is COFF! */
#define MULTIBOOT_FLAGS (MULTIBOOT_MEMORY_INFO | MULTIBOOT_AOUT_KLUDGE)
#endif
.extern SYMBOL_NAME(_startup)
.extern SYMBOL_NAME(_stkbase)
.extern SYMBOL_NAME(_stktop)
.extern SYMBOL_NAME(halt)
.data
ASMFILE(X0)
.globl SYMBOL_NAME(IDT)
.globl SYMBOL_NAME(GDT_base)
.globl SYMBOL_NAME(mb_signature)
.globl SYMBOL_NAME(mbi)
/* GDT Definition */
GDT:
.word 0,0,0,0 /* X_NULL_SEL */
.word 0,0,0,0 /* X_DATA16_SEL */
.word 0,0,0,0 /* X_CODE16_SEL */
.word 0,0,0,0 /* X_CODE32_SEL */
/* X_RM_BACK_GATE */
rmBckGateFix1: /* X_FLATCODE_SEL */
.word 0
.word X_FLATCODE_SEL
.word 0x8C00
rmBckGateFix2:
.word 0
.word 0,0,0,0 /* X_PM_BACK_GATE */
.word 0xFFFF /* X_FLATDATA_SEL */
.word 0
.word 0x9200
.word 0x00CF
.word 0xFFFF /* X_FLATCODE_SEL */
.word 0
.word 0x9A00
.word 0x00CF
.word 0,0,0,0 /* X_CALLBIOS_SEL */
.word 0,0,0,0 /* X_CALLBIOS_GATE */
.word 0,0,0,0 /* X_VM86_TSS */
.word 0,0,0,0 /* X_MAIN_TSS */
.fill 256 - 12,8,0
GDT_descr:
.word 256*8-1
SYMBOL_NAME_LABEL(GDT_base)
.long GDT
IDT_descr:
.word 256*8-1 # idt contains 256 entries
.long SYMBOL_NAME(IDT)
/* MultiBoot Data Stuff definition */
SYMBOL_NAME_LABEL(mb_signature) .long 0
SYMBOL_NAME_LABEL(mbi) .long 0
.bss /* This MUST be in the BSS !!! */
/* IDT definition */
SYMBOL_NAME_LABEL(IDT)
.fill 256,8,0 # idt is uninitialized
/* Protected mode stack */
base:
.space 8192,0
tos:
.text
.globl SYMBOL_NAME(_start)
.globl SYMBOL_NAME(__exit)
/*.globl SYMBOL_NAME(start)*/
.globl start
SYMBOL_NAME_LABEL(_start)
/*SYMBOL_NAME_LABEL(start)*/
start:
.align 8
/*start:*/
jmp boot_entry
/*
Here we go with the multiboot header...
---------------------------------------
*/
.align 8
boot_hdr:
.align 8
.long MULTIBOOT_MAGIC
.long MULTIBOOT_FLAGS
/* Checksum */
.long -(MULTIBOOT_MAGIC+MULTIBOOT_FLAGS)
#ifndef __LINUX__ /* COFF mode */
.long boot_hdr
/* .long SYMBOL_NAME(start)*/
.long start
.long _edata
.long _end
.long boot_entry
#endif
boot_entry: /* Just a brief debug check */
#ifdef __DEBUG__
/* A Brown 1 should appear... */
movl $0xB8000,%edi
addl $158,%edi
movb $'1',%gs:0(%edi)
incl %edi
movb $6,%gs:0(%edi)
#endif
/*
* Hopefully if it gets here, CS & DS are
* Correctly set for FLAT LINEAR mode
*/
/* Test if GDT is usable */
movl %gs:0(%ebx),%ecx
andl $0x0200,%ecx /* MB_INFO_BOOT_LOADER_NAME */
movl $0xB8000,%edi
addl $150,%edi
movb $'1',%gs:0(%edi)
incl %edi
movb $6,%gs:0(%edi)
jz GDT_is_not_OK
incl %edi
movb $'2',%gs:0(%edi)
incl %edi
movb $6,%gs:0(%edi)
movl %gs:64(%ebx), %ebp /* Name Address... */
cmpb $'X', %gs:0(%ebp)
je GDT_is_OK
GDT_is_not_OK:
/*
* Fix the X_RM_BACK_GATE with the address of halt()
*/
/* Now I test if the check mechanism is OK... */
movl $SYMBOL_NAME(halt),%eax
movw %ax,%gs:rmBckGateFix1
shrl $16,%eax
movw %ax,%gs:rmBckGateFix2
/* Load GDT, using the predefined assignment! */
lgdt GDT_descr
movl $0xB8000,%edi
addl $146,%edi
movb $'0',%gs:0(%edi)
incl %edi
movb $6,%gs:0(%edi)
GDT_is_OK: movw $(X_FLATDATA_SEL),%ax
movw %ax,%ds
movw %ax,%es
movw %ax,%ss
movw %ax,%fs
movw %ax,%gs
movl $tos,%esp
movl $base,SYMBOL_NAME(_stkbase)
movl $tos,SYMBOL_NAME(_stktop)
/* Store the MULTIBOOT informations */
movl %eax,SYMBOL_NAME(mb_signature)
movl %ebx,SYMBOL_NAME(mbi)
/* Store the X passed GDT address!
* If GDT is not available is a dummy instruction!
*/
sgdt GDT_descr
/* Now probably is the case to load CS... */
ljmp $X_FLATCODE_SEL, $load_cs
load_cs:
/* Load IDT */
lidt IDT_descr
cld
call SYMBOL_NAME(_startup)
/* Well I hope when I reach this
The X_RM_BACK_GATE has been setup correctly
even if the kernel has not been loaded through X!
*/
.byte 0x0EA /* Direct gate jmp */
.long 0
.word X_RM_BACK_GATE
/* Simple function to terminate PM application */
/* void __exit(int code) */
SYMBOL_NAME_LABEL(__exit)
pushl %ebp
movl %esp,%ebp
movl 8(%ebp),%eax
.byte 0x0ea /* Direct gate jmp */
.long 0
.word X_RM_BACK_GATE