fix

Author: PythonPlumber

.traerules

@@ -0,0 +1,20 @@
+# OS Development Rules for Cursor
+
+## Environment Context
+- We are building a **freestanding x86 kernel**.
+- **NO Standard Library:** Do not use <stdio.h>, <stdlib.h>, <string.h>, etc.
+- **Allowed Headers:** <stdint.h>, <stddef.h>, <stdbool.h>, and <limits.h>.
+- **Target Architecture:** x86 (32-bit/i686).
+- **Bootloader:** Multiboot compliant (GRUB).
+
+## Coding Preferences
+- Use **Pointer Arithmetic** for memory-mapped I/O (e.g., VGA buffer at 0xB8000).
+- Use **Inline Assembly** (`__asm__ __volatile__`) for CPU instructions like `inb`, `outb`, `cli`, `hlt`, and `lgdt`.
+- Prefer `uint8_t`, `uint16_t`, and `uint32_t` for hardware-specific structures to ensure exact sizing.
+- All structures representing hardware tables (GDT, IDT) MUST be marked with `__attribute__((packed))`.
+
+## Project Structure
+- `/src/boot`: Assembly entry files (.s)
+- `/src/kernel`: Main C logic (.c)
+- `/src/drivers`: Hardware drivers (VGA, Keyboard, etc.)
+- `/include`: Header files (.h)

CMakeLists.txt

@@ -1,5 +1,9 @@
 cmake_minimum_required(VERSION 3.16)
 
+# For freestanding projects (kernels), we don't have a standard library yet.
+# Tell CMake to only test the compiler by creating a static library instead of an executable.
+set(CMAKE_TRY_COMPILE_TARGET_TYPE "STATIC_LIBRARY")
+
 # Force the NASM object format to 32-bit ELF
 set(CMAKE_ASM_NASM_OBJECT_FORMAT elf32)
 set(CMAKE_ASM_NASM_FLAGS "-f elf32")
@@ -32,6 +36,11 @@ include_directories(include)
 file(GLOB_RECURSE ASM_SOURCES "src/*.asm")
 file(GLOB_RECURSE C_SOURCES "src/*.c")
 
+# Ensure boot.asm is ALWAYS FIRST in the link order to keep Multiboot header at the top
+set(BOOT_ASM "${CMAKE_CURRENT_SOURCE_DIR}/src/boot.asm")
+list(REMOVE_ITEM ASM_SOURCES "${BOOT_ASM}")
+set(ASM_SOURCES "${BOOT_ASM}" ${ASM_SOURCES})
+
 # Exclude specific files if needed
 list(FILTER C_SOURCES EXCLUDE REGEX "src/drivers/vga.c")
 

linker.ld

@@ -7,8 +7,9 @@ SECTIONS
 
     .text BLOCK(4K) : ALIGN(4K)
     {
-        *(.multiboot)
-        *(.text*)
+        /* MUST be at the very top of the binary */
+        KEEP(*(.multiboot))
+        *(.text)
     }
 
     .rodata BLOCK(4K) : ALIGN(4K)

src/boot.asm

@@ -1,26 +1,24 @@
-[bits 32]
-
 section .multiboot
 align 4
-dd 0x1BADB002
-dd 0x00000000
-dd 0xE4524FFE
+    dd 0x1BADB002             ; Magic number
+    dd 0x00000003             ; Flags (align modules + mem info)
+    dd -(0x1BADB002 + 0x00000003) ; Checksum
 
 section .text
 global _start
 extern kernel_main
 
 _start:
-    cli
+    ; Setup stack and call kernel_main
     mov esp, stack_top
-    push ebx
-    push eax
+    push ebx                  ; Pointer to Multiboot info
     call kernel_main
-    add esp, 8
-    jmp $
+    cli
+.hang: hlt
+    jmp .hang
 
 section .bss
 align 16
 stack_bottom:
-    resb 16384
+    resb 16384 ; 16 KB stack
 stack_top: