Added a secondary stage bootloader.

CMakeLists.txt

@@ -5,6 +5,7 @@ set(CMAKE_BINARY_DIR ${CMAKE_CURRENT_LIST_DIR}/build)
 
 include(x86-baremetal-toolchain.cmake)
 
+project(ClassicOSBL VERSION 0.0.1 LANGUAGES ASM_NASM)
 project(ClassicOS VERSION 0.0.1 LANGUAGES C CXX ASM_NASM)
 
 set(IS_OS_WINDOWS FALSE)
@@ -28,12 +29,10 @@ set(BOOT_SOURCE_FILES
     src/boot/linker.ld
 )
 
-#[[
 set(GRUB_SOURCE_FILES
     src/boot/grub/grub.cfg
     src/boot/grub/menu.lst
 )
-]]
 
 set(DRIVERS_SOURCE_FILES
     src/drivers/audio/audio.c
@@ -111,18 +110,13 @@ set(UTIL_SOURCE_FILES
 )
 
 add_executable(ClassicOS
-    ${GRUB_SOURCE_FILES}
 	${KERNEL_SOURCE_FILES}
     ${DRIVERS_SOURCE_FILES}
 )
 
-if (IS_OS_LINUX)
+add_executable(ClassicOSBL
-	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -m32")
+	${BOOT_SOURCE_FILES}
-	set(CMAKE_ASM_NASM_FLAGS "${CMAKE_ASM_NASM_FLAGS} -f elf")
+	${GRUB_SOURCE_FILES}
-	set(CMAKE_EXE_LINKER_FLAGS "-g -s")
+)
-	set(CMAKE_LINK_FLAGS "${CMAKE_LINK_FLAGS} -e kernel_main")
 
-	#set_target_properties(ClassicOS PROPERTIES LINK_FLAGS "-T ${CMAKE_CURRENT_SOURCE_DIR}/linker.ld")
+message("${CMAKE_EXE_LINKER_FLAGS}")
-elseif (IS_OS_WINDOWS)
-	set(CMAKE_ASM_NASM_FLAGS "${CMAKE_ASM_NASM_FLAGS} -f win32")
-endif ()

src/boot/boot.asm

@@ -1,112 +1,87 @@
 [BITS 16]
+[ORG 0x7c00]
 
-; Set up the segment registers
+start:
-xor ax, ax
+    XOR AX, AX
-mov ds, ax
+    MOV DS, AX
-mov es, ax
+    MOV SS, AX
+    MOV SP, 0x7c00
 
-; Set up stack and jump to main
+    MOV SI, loading
-mov ss, ax
+    CALL printnl
-mov sp, 0x7c00
-jmp main
 
-; Print 'Booting ClassicOS!' to the screen
+    CALL reset_drives
-print:
+    CALL read_drive
-   mov si, message
-   mov ah, 0x0e
-.loop:
-   lodsb
-   test al, al
-   jz .done
-   int 0x10
-   jmp .loop
-.done:
-   ret
 
-; Set the video mode to a 40 column text mode
+    MOV SI, loadedSS
-set_video_mode:
+    CALL printnl
-   mov ax, 0x0003    ; Set up a 80x25 text mode
-   int 0x10
 
-   ; Set the number of columns to 40
+    JMP 0x1000:0x0000
-   mov ax, 0x1112
-   mov bx, 0x0007
-   int 0x10
 
-   ret
+    RET
 
-; Detect floppy disk drive
+printnl:
-detect_disk:
+    LODSB
-   mov ah, 0x08
+    OR AL, AL
-   int 0x13
+    JZ .stop
-   cmp ah, 0
-   jne .error
-   ret
 
-.error:
+    MOV AH, 0x0E
-   ; Handle disk detection error
+    MOV BH, 0x00
-   ; Display error message or take appropriate action
+    MOV BL, 0x07
-   ret
+    INT 0x10
 
-; Read sectors from floppy disk
+    JMP printnl
-read_sectors:
-   mov ah, 0x02
-   mov al, 1  ; Number of sectors to read
-   mov ch, 0  ; Cylinder/Track number
-   mov cl, 2  ; Sector number (starting from 1)
-   mov dh, 0  ; Head number
-   mov dl, 0  ; Drive number (0 for floppy disk)
 
-   mov bx, buffer  ; Destination buffer
+    .stop:
-   mov es, bx
+        MOV AH, 0x03  ; AH = 0x03 (Get Cursor Position and Shape)
-   xor bx, bx
+        XOR BH, BH    ; BH = 0x00 (Video Page Number)
+        INT 0x10      ; Call video interrupt
 
-   int 0x13
+        INC DH
 
-   jc .error  ; Check carry flag for error
+        MOV AH, 0x02  ; Set cursor position
-   ret
+        XOR BH, BH    ; Page number
+        XOR DL, DL    ; Column (start from 0)
+        INT 0x10      ; Call video interrupt
+        RET
 
-.error:
+reset_drives:
-   ; Handle read error
+    XOR AH, AH         ; 0 = Reset floppy disk
-   ; Display error message or take appropriate action
+    INT 0x13
-   ret
+    JC .reset_error          ; If carry flag was set, try again
+    RET
 
-; Bootloader entry point
+    .reset_error:
-main:
+        MOV SI, resetError
-   ; Call the set_video_mode function
+        CALL printnl
-   call set_video_mode
+        RET
 
-   ; Clear the screen
+read_drive:
-   mov ah, 0x06
+    MOV AH, 0x02
-   mov al, 0
+    MOV AL, 1  ; Number of sectors to read
-   xor bx, bx
+    XOR CH, CH  ; Cylinder/Track number
-   xor cx, cx
+    MOV CL, 2  ; Sector number (starting from 1)
-   mov dh, 24
+    XOR DH, DH  ; Head number
-   mov dl, 39
+    XOR DL, DL  ; Drive number (0x0 for floppy disk / 0x80 for hard disk)
-   int 0x10
 
-   ; Call the print function
+    MOV BX, 0x1000
-   call print
+    MOV ES, BX
+    XOR BX, BX
 
-   ; Wait for a key press to exit the loop
+    INT 0x13
-   mov ah, 0x00
-   int 0x16
 
-   ; Call the detect_disk function
+    JC .read_error
-   call detect_disk
+    RET
 
-   ; Call the read_sectors function
+    .read_error:
-   call read_sectors
+        MOV SI, readError
+        CALL printnl
+        RET
 
-   ; Infinite loop
+loading db "Loading Second Stage", 0
-.loop:
+resetError db "Failed to reset drives.", 0
-   jmp .loop
+readError db "Failed to read drive", 0
-
+loadedSS db "Loaded second stage...", 0
-; Message to print
-message db 'Booting ClassicOS!', 0
-
-; Buffer to store read sectors
-buffer times 512 db 0
 
 times 510-($-$$) db 0
 dw 0xaa55

src/boot/boot2.asm

@@ -0,0 +1,43 @@
+[BITS 16]
+[ORG 0x0000]
+
+start:
+    MOV AX, CS
+    MOV DS, AX
+    MOV SS, AX
+    MOV SP, 0xFFFF
+
+    MOV SI, msg
+    JMP println
+
+    JMP $
+
+    RET
+
+println:
+    .next_char:
+        LODSB
+        OR AL, AL
+        JZ .stop
+
+        MOV AH, 0x0E
+        MOV BH, 0x00
+        MOV BL, 0x07
+        INT 0x10
+
+        JMP .next_char
+
+    .stop:
+        MOV AH, 0x03  ; AH = 0x03 (Get Cursor Position and Shape)
+        XOR BH, BH    ; BH = 0x00 (Video Page Number)
+        INT 0x10      ; Call video interrupt
+
+        INC DH
+
+        MOV AH, 0x02  ; Set cursor position
+        XOR BH, BH    ; Page number
+        XOR DL, DL    ; Column (start from 0)
+        INT 0x10      ; Call video interrupt
+        RET
+
+msg db "Second stage loaded, and Gbowne1 stinks.", 0

src/kernel/linker.ld

@@ -1,21 +1,33 @@
 ENTRY(kernel_main)
 
+PHDRS {
+    headers PT_PHDR PHDRS ;
+    text_seg PT_LOAD FLAGS(5); /* Read and Execute */
+    data_seg PT_LOAD FLAGS(6); /* Read and Write */
+}
+
 SECTIONS {
-    . = 0x100000;
+    . = 0xC0000000;  /* Starting virtual address */
 
-    .text : {
+    /* Text Section */
+    .text : AT(ADDR(.text) - 0xC0000000)
+    {
         *(.text)
-    }
+    } :text_seg
 
-    .rodata : {
+    . = ALIGN(4096);  /* Align to page boundary */
-        *(.rodata)
-    }
 
-    .data : {
+    /* Data Section */
+    .data : AT(ADDR(.data) - 0xC0000000)
+    {
         *(.data)
-    }
+    } :data_seg
 
-    .bss : {
+    . = ALIGN(4096);  /* Align to page boundary */
+
+    /* BSS Section */
+    .bss : AT(ADDR(.bss) - 0xC0000000)
+    {
         *(.bss)
-    }
+    } :data_seg  /* Use the same segment as .data */
 }

x86-baremetal-toolchain.cmake

@@ -12,4 +12,4 @@ set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_ASM_NASM_FLAGS "-f elf32")
 set(CMAKE_C_FLAGS "-m32 -ffreestanding -nostdlib")
 set(CMAKE_CXX_FLAGS "-m32 -ffreestanding -nostdlib")
-set(CMAKE_EXE_LINKER_FLAGS "-T${CMAKE_CURRENT_LIST_DIR}/linker.ld -m32")
+set(CMAKE_EXE_LINKER_FLAGS "-e kernel_main -T${CMAKE_CURRENT_LIST_DIR}/linker.ld -m32 -z noexecstack")