First working version

build.zig

@@ -20,17 +20,79 @@ pub fn build(b: *std.Build) void {
     };
     const optimize = b.standardOptimizeOption(.{});
 
-    const kernel = b.addExecutable(.{
+    const kernel_elf = b.addExecutable(.{
         .name = "kernel.elf",
         .root_source_file = b.path("src/main.zig"),
         .target = b.resolveTargetQuery(target_query),
         .optimize = optimize,
         .code_model = .kernel,
     });
+    kernel_elf.setLinkerScript(b.path("src/linker.ld"));
 
-    kernel.setLinkerScript(b.path("src/linker.ld"));
-    b.installArtifact(kernel);
+    const kernel_elf_artifact = b.addInstallArtifact(kernel_elf, .{});
 
-    const kernel_step = b.step("kernel", "Build the kernel");
-    kernel_step.dependOn(&kernel.step);
+    const kernel_bin = b.addObjCopy(kernel_elf.getEmittedBin(), .{
+        .format = .bin,
+        .only_section = ".blob",
+    });
+    kernel_bin.step.dependOn(&kernel_elf_artifact.step);
+
+    const kernel_bin_copy = b.addInstallBinFile(
+        kernel_bin.getOutput(),
+        "kernel.bin",
+    );
+    kernel_bin_copy.step.dependOn(&kernel_bin.step);
+
+    const kernel_step_elf = b.step("elf", "Build the kernel ELF");
+    kernel_step_elf.dependOn(&kernel_elf.step);
+
+    const kernel_step_bin = b.step("bin", "Build the kernel BIN (with objcopy)");
+    kernel_step_bin.dependOn(&kernel_bin_copy.step);
+
+    const iso_dir_path = b.fmt("{s}/iso_dir", .{b.cache_root.path.?});
+    const iso_dir_boot_path = b.fmt("{s}/boot", .{iso_dir_path});
+    const grub_dir_path = b.fmt("{s}/{s}", .{ iso_dir_boot_path, "grub" });
+
+    const iso_make_dir = b.addSystemCommand(&[_][]const u8{
+        "mkdir",
+        "-p",
+        grub_dir_path,
+    });
+
+    const iso_copy_kernel = b.addSystemCommand(&[_][]const u8{
+        "cp",
+        b.fmt("{s}/bin/{s}", .{ b.install_path, "kernel.elf" }),
+        iso_dir_boot_path,
+    });
+    iso_copy_kernel.step.dependOn(&iso_make_dir.step);
+    iso_copy_kernel.step.dependOn(kernel_step_elf);
+
+    const iso_copy_grubcfg = b.addSystemCommand(&[_][]const u8{
+        "cp",
+        "src/grub.cfg",
+        grub_dir_path,
+    });
+    iso_copy_grubcfg.step.dependOn(&iso_make_dir.step);
+
+    const iso_make_iso = b.addSystemCommand(&[_][]const u8{
+        "grub2-mkrescue",
+        "-o",
+        b.fmt("{s}/{s}", .{ b.install_path, "kernel.iso" }),
+        iso_dir_path,
+    });
+    iso_make_iso.step.dependOn(&iso_copy_grubcfg.step);
+    iso_make_iso.step.dependOn(&iso_copy_kernel.step);
+
+    const iso_step = b.step("iso", "Create bootable iso using GRUB2");
+    iso_step.dependOn(&iso_make_iso.step);
+
+    const run_qemu = b.addSystemCommand(&[_][]const u8{
+        "qemu-system-i386",
+        "-cdrom",
+        b.fmt("{s}/{s}", .{ b.install_path, "kernel.iso" }),
+    });
+    run_qemu.step.dependOn(&iso_make_iso.step);
+
+    const run_qemu_step = b.step("run", "Run in qemu");
+    run_qemu_step.dependOn(&run_qemu.step);
 }

src/grub.cfg

@@ -1,3 +1,3 @@
 menuentry "Zig Bare Bones" {
 	multiboot /boot/kernel.elf
-}
+}

src/linker.ld

@@ -1,13 +1,10 @@
 ENTRY(_start)
  
 SECTIONS {
-    . = 1M;
- 
-    .multiboot {
-        KEEP(*(.multiboot))
-    }
+    . = 2M;
 
     .text : ALIGN(4K) {
+        *(.multiboot)
         *(.text)
     }
  
@@ -23,4 +20,8 @@ SECTIONS {
         *(COMMON)
         *(.bss)
     }
-}
+
+    /DISCARD/ : {
+        *(.note .note.*)
+    }
+}

src/main.zig

@@ -9,6 +9,7 @@ const MultibootHeader = packed struct {
     magic: i32 = MAGIC,
     flags: i32,
     checksum: i32,
+    padding: u32 = 0,
 };
 
 export var multiboot align(4) linksection(".multiboot") = MultibootHeader{
@@ -20,13 +21,17 @@ export var stack_bytes: [16 * 1024]u8 align(16) linksection(".bss") = undefined;
 const stack_bytes_slice = stack_bytes[0..];
 
 export fn _start() callconv(.Naked) noreturn {
-    @call(.auto, kmain, .{});
-    //kmain();
-
+    asm volatile (
+        \\ movl %[stk], %esp
+        \\ movl %esp, %ebp
+        \\ call kmain
+        :
+        : [stk] "{ecx}" (@intFromPtr(&stack_bytes_slice) + @sizeOf(@TypeOf(stack_bytes_slice))),
+    );
     while (true) {}
 }
 
-fn kmain() void {
+export fn kmain() void {
     console.initialize();
     console.puts("Hello world!");
 }