Change to limine bootloader

.clangd.template

@@ -1,9 +1,9 @@
 CompileFlags:
-  Compiler: i686-elf-gcc
+  Compiler: x86_64-elf-gcc
   Add:
     - "-target"
-    - "i686-elf"
+    - "x86_64-elf"
     - "-ffreestanding"
     - "-nostdlibinc"
     - "-isystem"
-    - "${env:I686_ELF_GCC_INCLUDE}"
+    - "${env:X86_64_ELF_GCC_INCLUDE}"

nob.c

@@ -11,14 +11,14 @@ bool render_clangd_config(void) {
         return false;
     nob_sb_append_null(&tmpl);
 
-    const char *include_path = getenv("I686_ELF_GCC_INCLUDE");
+    const char *include_path = getenv("x86_64_ELF_GCC_INCLUDE");
     if (include_path == NULL) {
-        nob_log(NOB_ERROR, "I686_ELF_GCC_INCLUDE not set");
+        nob_log(NOB_ERROR, "x86_64_ELF_GCC_INCLUDE not set");
         nob_sb_free(tmpl);
         return false;
     }
 
-    const char *needle = "${env:I686_ELF_GCC_INCLUDE}";
+    const char *needle = "${env:X86_64_ELF_GCC_INCLUDE}";
     Nob_String_Builder out = {0};
 
     const char *cursor = tmpl.items;
@@ -45,7 +45,7 @@ bool build_assembly(Nob_Cmd *cmd) {
     if (!rebuild)
         return true;
 
-    nob_cmd_append(cmd, "i686-elf-as", "-o", BUILD_FOLDER "boot.o", SRC_FOLDER "boot.s");
+    nob_cmd_append(cmd, "x86_64-elf-as", "-o", BUILD_FOLDER "boot.o", SRC_FOLDER "boot.s");
     if (!nob_cmd_run(cmd))
         return false;
 
@@ -61,9 +61,14 @@ bool build_c(Nob_Cmd *cmd) {
         return true;
 
     nob_cmd_append(cmd,
-                   "i686-elf-gcc",
+                   "x86_64-elf-gcc",
                    "-std=gnu99",
                    "-ffreestanding",
+                   "-mcmodel=large",
+                   "-mno-red-zone",
+                   "-mno-mmx",
+                   "-mno-sse",
+                   "-mno-sse2",
                    "-Wall",
                    "-Wextra",
                    "-O2",
@@ -86,7 +91,7 @@ bool link_everything(Nob_Cmd *cmd) {
 
     const char *objectFiles[] = {BUILD_FOLDER "kernel.o", BUILD_FOLDER "boot.o"};
     nob_cmd_append(cmd,
-                   "i686-elf-gcc",
+                   "x86_64-elf-gcc",
                    "-T", SRC_FOLDER "linker.ld",
                    "-o", BUILD_FOLDER "kernel",
                    "-ffreestanding",
@@ -137,10 +142,10 @@ bool clean_dir(const char *dir_path) {
 }
 
 bool build_bootable_image(Nob_Cmd *cmd) {
+    // NOTE: this does not rebuild on change of limine bins
     const char *output = BUILD_FOLDER "kernel.iso";
-    const char *input[] = {BUILD_FOLDER "kernel", SRC_FOLDER "grub.cfg"};
+    const char *input[] = {BUILD_FOLDER "kernel", SRC_FOLDER "limine.conf"};
     int rebuild = nob_needs_rebuild(output, input, NOB_ARRAY_LEN(input));
-
     if (!rebuild)
         return true;
 
@@ -148,18 +153,58 @@ bool build_bootable_image(Nob_Cmd *cmd) {
         return false;
     if (!nob_mkdir_if_not_exists(BUILD_FOLDER "isodir/boot"))
         return false;
-    if (!nob_mkdir_if_not_exists(BUILD_FOLDER "isodir/boot/grub"))
+    if (!nob_mkdir_if_not_exists(BUILD_FOLDER "isodir/boot/limine"))
+        return false;
+    if (!nob_mkdir_if_not_exists(BUILD_FOLDER "isodir/EFI"))
+        return false;
+    if (!nob_mkdir_if_not_exists(BUILD_FOLDER "isodir/EFI/BOOT"))
+        return false;
+    if (!nob_mkdir_if_not_exists(BUILD_FOLDER "limine"))
         return false;
 
-    nob_cmd_append(cmd, "cp", BUILD_FOLDER "kernel", BUILD_FOLDER "isodir/boot/kernel");
+    if (!nob_file_exists(BUILD_FOLDER "limine")) {
+        nob_cmd_append(cmd, "git", "clone", "https://github.com/limine-bootloader/limine.git", "--branch=v11.x-binary", "--depth=1", BUILD_FOLDER "limine");
+        if (!nob_cmd_run(cmd))
+            return false;
+    }
+
+    nob_cmd_append(cmd, "make", "-C", BUILD_FOLDER "limine");
     if (!nob_cmd_run(cmd))
         return false;
 
-    nob_cmd_append(cmd, "cp", SRC_FOLDER "grub.cfg", BUILD_FOLDER "isodir/boot/grub/grub.cfg");
+    nob_cmd_append(cmd, "cp",
+                   BUILD_FOLDER "limine/limine-bios.sys",
+                   BUILD_FOLDER "limine/limine-bios-cd.bin",
+                   BUILD_FOLDER "limine/limine-uefi-cd.bin",
+                   BUILD_FOLDER "isodir/boot/limine/");
     if (!nob_cmd_run(cmd))
         return false;
 
-    nob_cmd_append(cmd, "grub-mkrescue", "-o", BUILD_FOLDER "kernel.iso", BUILD_FOLDER "isodir");
+    nob_cmd_append(cmd, "cp",
+                   BUILD_FOLDER "limine/BOOTIA32.EFI",
+                   BUILD_FOLDER "limine/BOOTX64.EFI",
+                   BUILD_FOLDER "isodir/EFI/BOOT/");
+    if (!nob_cmd_run(cmd))
+        return false;
+
+    nob_cmd_append(cmd, "cp", SRC_FOLDER "limine.conf", BUILD_FOLDER "isodir/boot/limine/limine.conf");
+    if (!nob_cmd_run(cmd))
+        return false;
+
+    nob_cmd_append(cmd, "cp", BUILD_FOLDER "kernel", BUILD_FOLDER "isodir/boot/");
+    if (!nob_cmd_run(cmd))
+        return false;
+
+    nob_cmd_append(cmd, "xorriso", "-as", "mkisofs",
+                   "-b", "boot/limine/limine-bios-cd.bin",
+                   "-no-emul-boot", "-boot-load-size", "4", "-boot-info-table",
+                   "--efi-boot", "boot/limine/limine-uefi-cd.bin",
+                   "-efi-boot-part", "--efi-boot-image", "--protective-msdos-label",
+                   BUILD_FOLDER "isodir", "-o", BUILD_FOLDER "kernel.iso");
+    if (!nob_cmd_run(cmd))
+        return false;
+
+    nob_cmd_append(cmd, BUILD_FOLDER "limine/limine", "bios-install", BUILD_FOLDER "kernel.iso");
     if (!nob_cmd_run(cmd))
         return false;
 
@@ -167,7 +212,7 @@ bool build_bootable_image(Nob_Cmd *cmd) {
 }
 
 bool runQemu(Nob_Cmd *cmd) {
-    nob_cmd_append(cmd, "qemu-system-i386", "-cdrom", BUILD_FOLDER "kernel.iso", "-serial", "stdio");
+    nob_cmd_append(cmd, "qemu-system-x86_64", "-cdrom", BUILD_FOLDER "kernel.iso", "-serial", "stdio");
     if (!nob_cmd_run(cmd))
         return false;
     return true;

shell.nix

@@ -3,15 +3,16 @@
 pkgs.mkShell {
   nativeBuildInputs =
     with pkgs; [
-      pkgsCross.i686-embedded.buildPackages.gcc
+      pkgsCross.x86_64-embedded.buildPackages.gcc
-      pkgsCross.i686-embedded.buildPackages.binutils
+      pkgsCross.x86_64-embedded.buildPackages.binutils      
       gdb
       grub2
       xorriso
       qemu
+      limine
     ];
 
   shellHook = ''
-    export I686_ELF_GCC_INCLUDE="${pkgs.pkgsCross.i686-embedded.buildPackages.gcc.cc}/lib/gcc/i686-elf/${pkgs.pkgsCross.i686-embedded.buildPackages.gcc.version}/include"
+    export x86_64_ELF_GCC_INCLUDE="${pkgs.pkgsCross.x86_64-embedded.buildPackages.gcc.cc}/lib/gcc/x86_64-elf/${pkgs.pkgsCross.x86_64-embedded.buildPackages.gcc.version}/include"
   '';
 }

src/boot.s

@@ -20,8 +20,9 @@ stack_top:
 	.section .text
 	.global _start
 	.type _start, @function
+
 _start:
-	mov $stack_top, %esp
+	mov $stack_top, %rsp
 
 	/* Initialize processor state here */
 

src/kernel.c

@@ -6,10 +6,24 @@
 #if defined(__linux__)
 #error "Not using cross compiler"
 #endif
-#if !defined(__i386__)
+#if !defined(__x86_64__)
-#error "Not using a ix86-elf compiler"
+#error "Not using a x86_64-elf compiler"
 #endif
 
+static inline uint64_t read_msr(uint32_t msr) {
+    uint32_t lo, hi;
+    __asm__ volatile("rdmsr" : "=a"(lo), "=d"(hi) : "c"(msr));
+    return ((uint64_t)hi << 32) | lo;
+}
+
+#define IA32_EFER 0xC0000080
+#define EFER_LMA (1 << 10)
+
+int is_long_mode_active(void) {
+    uint64_t efer = read_msr(IA32_EFER);
+    return (efer & EFER_LMA) != 0;
+}
+
 void kernel_main(void) {
     init_serial();
     if (!test_serial()) {
@@ -17,4 +31,10 @@ void kernel_main(void) {
         return;
     }
     serial_log(S_LOG, "Init serial succesfully.");
+
+    if (!is_long_mode_active()) {
+        serial_log(S_ERR, "Kernel is not in long mode!");
+        return;
+    }
+    serial_log(S_LOG, "Kernel is in long mode.");
 }

src/limine.conf

@@ -0,0 +1,3 @@
+/SimpleKernel
+    protocol: multiboot1
+    kernel_path: boot():/boot/kernel