Update MentOs code to the latest development version.

2021-10-04 11:44:02 +02:00
parent 6fd063984a
commit b01eccca2e
484 changed files with 42358 additions and 20285 deletions
@@ -0,0 +1,103 @@
+;                MentOS, The Mentoring Operating system project
+; @file boot.asm
+; @brief Kernel start location, multiboot header
+; @copyright (c) 2014-2021 This file is distributed under the MIT License.
+; See LICENSE.md for details.
+
+bits 32             ; All instructions should be 32-bit.
+extern boot_main    ; The start point of our C code
+
+; The magic field should contain this.
+MULTIBOOT_HEADER_MAGIC     equ 0x1BADB002
+; This should be in %eax.
+MULTIBOOT_BOOTLOADER_MAGIC equ 0x2BADB002
+
+; = Specify what GRUB should PROVIDE =========================================
+; Align the kernel and kernel modules on i386 page (4KB) boundaries.
+MULTIBOOT_PAGE_ALIGN  equ 0x00000001
+; Provide the kernel with memory information.
+MULTIBOOT_MEMORY_INFO equ 0x00000002
+; Must pass video information to OS.
+MULTIBOOT_VIDEO_MODE  equ 0x00000004
+; -----------------------------------------------------------------------------
+
+; This is the flag combination that we prepare for Grub
+; to read at kernel load time.
+MULTIBOOT_HEADER_FLAGS  equ (MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO | MULTIBOOT_VIDEO_MODE)
+; Grub reads this value to make sure it loads a kernel
+; and not just garbage.
+MULTIBOOT_CHECKSUM      equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
+
+LOAD_MEMORY_ADDRESS equ 0x00000000
+; reserve (1024*1024) for the stack on a doubleword boundary
+KERNEL_STACK_SIZE   equ 0x100000
+
+; -----------------------------------------------------------------------------
+; SECTION (multiboot_header)
+; -----------------------------------------------------------------------------
+section .multiboot_header
+align 4
+; This is the GRUB Multiboot header.
+multiboot_header:
+    ; magic
+    dd MULTIBOOT_HEADER_MAGIC
+    ; flags
+    dd MULTIBOOT_HEADER_FLAGS
+    ; checksum
+    dd MULTIBOOT_CHECKSUM
+
+; -----------------------------------------------------------------------------
+; SECTION (data)
+; -----------------------------------------------------------------------------
+; section .data nobits
+; align 4096
+
+; -----------------------------------------------------------------------------
+; SECTION (text)
+; -----------------------------------------------------------------------------
+section .text
+global boot_entry
+boot_entry:
+    ; Clear interrupt flag [IF = 0]; 0xFA
+    cli
+    ; To set up a stack, we simply set the esp register to point to the top of
+    ; our stack (as it grows downwards).
+    mov esp, stack_top
+    ; pass the initial ESP
+    push esp
+    ; pass Multiboot info structure
+    push ebx
+    ; pass Multiboot magic number
+    push eax
+    ; Call the boot_main() function inside boot.c
+    call boot_main
+    ; Set interrupt flag [IF = 1]; 0xFA
+    ; Clear interrupts and hang if we return from boot_main
+    cli
+hang:
+    hlt
+    jmp hang
+
+global boot_kernel
+boot_kernel:
+    mov edx, [esp + 4] ; stack_pointer
+    mov ebx, [esp + 8] ; entry
+    mov eax, [esp + 12] ; boot info
+    mov esp, edx ; set stack pointer
+    push eax ; push the boot info
+    call ebx ; call the kernel main
+
+
+; -----------------------------------------------------------------------------
+; SECTION (bss)
+; -----------------------------------------------------------------------------
+section .bss
+align 16
+
+global stack_bottom
+stack_bottom:
+    resb KERNEL_STACK_SIZE
+
+global stack_top
+stack_top:
+    ; the top of the stack is the bottom because the stack counts down