.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

@@ -1,6 +1,9 @@
-.zig-cache/
+# Zig
-zig-out/
+zig-*
+.zig-*
 
-.envrc
+# Nix
-.direnv/
+result*
 
+# Misc
+.direnv

build.zig

@@ -1,31 +1,32 @@
 const std = @import("std");
 
-pub fn build(b: *std.Build) void {
+pub fn build(b: *std.Build) !void {
+    var disabled_features = std.Target.Cpu.Feature.Set.empty;
+    var enabled_features = std.Target.Cpu.Feature.Set.empty;
+
+    disabled_features.addFeature(@intFromEnum(std.Target.x86.Feature.mmx));
+    disabled_features.addFeature(@intFromEnum(std.Target.x86.Feature.sse));
+    disabled_features.addFeature(@intFromEnum(std.Target.x86.Feature.sse2));
+    disabled_features.addFeature(@intFromEnum(std.Target.x86.Feature.avx));
+    disabled_features.addFeature(@intFromEnum(std.Target.x86.Feature.avx2));
+
+    enabled_features.addFeature(@intFromEnum(std.Target.x86.Feature.soft_float));
+
     const target = b.resolveTargetQuery(.{
         .cpu_arch = std.Target.Cpu.Arch.x86,
-        .ofmt = std.Target.ObjectFormat.elf,
         .abi = std.Target.Abi.none,
         .os_tag = std.Target.Os.Tag.freestanding,
-        .cpu_features_sub = std.Target.x86.featureSet(&.{
+        .cpu_features_sub = disabled_features,
-            .mmx,
+        .cpu_features_add = enabled_features,
-            .sse,
-            .sse2,
-            .avx,
-            .avx2,
-        }),
-        .cpu_features_add = std.Target.x86.featureSet(&.{
-            .soft_float,
-        }),
     });
 
-    const optimize = b.standardOptimizeOption(.{});
-
     const kernel = b.addExecutable(.{
-        .name = "kernel",
+        .name = "kernel.elf",
         .root_module = b.createModule(.{
-            .target = target,
-            .optimize = optimize,
             .root_source_file = b.path("src/main.zig"),
+            .target = target,
+            .optimize = .ReleaseFast,
+            .code_model = .kernel,
         }),
     });
     kernel.setLinkerScript(b.path("kernel.ld"));
@@ -41,4 +42,3 @@ pub fn build(b: *std.Build) void {
     const run = b.step("run", "Run QEMU");
     run.dependOn(&qemu.step);
 }
-

flake.lock

@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1757745802,
+        "lastModified": 1762363567,
-        "narHash": "sha256-hLEO2TPj55KcUFUU1vgtHE9UEIOjRcH/4QbmfHNF820=",
+        "narHash": "sha256-YRqMDEtSMbitIMj+JLpheSz0pwEr0Rmy5mC7myl17xs=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "c23193b943c6c689d70ee98ce3128239ed9e32d1",
+        "rev": "ae814fd3904b621d8ab97418f1d0f2eb0d3716f4",
         "type": "github"
       },
       "original": {

src/Console.zig

@@ -119,22 +119,29 @@ const Writer = struct {
     console: *Self,
     interface: std.Io.Writer,
 
-    fn drain(w: *std.Io.Writer, data: []const []const u8, splat: usize) std.Io.Writer.Error!usize {
+    fn drain(io_w: *std.Io.Writer, data: []const []const u8, splat: usize) std.Io.Writer.Error!usize {
-        _ = splat;
+        const self: *@This() = @fieldParentPtr("interface", io_w);
 
-        const self: *@This() = @alignCast(@fieldParentPtr("interface", w));
+        try self.puts(io_w.buffered());
+        io_w.end = 0;
 
-        const buffered = w.buffered();
+        for (data[0..data.len - 1]) |bytes| {
-        if (buffered.len != 0) {
+            try self.puts(bytes);
-            self.console.puts(buffered);
-            return w.consume(buffered.len);
         }
-        self.console.puts(data[0]);
+        const pattern = data[data.len - 1];
-        return data[0].len;
+        for (0..splat) |_| {
+            try self.puts(pattern);
+        }
+
+        return std.Io.Writer.countSplat(data, splat);
+    }
+
+    fn puts(self: *@This(), data: []const u8) std.Io.Writer.Error!void {
+        self.console.puts(data);
     }
 };
 
-fn writer(self: *Self, buffer: []u8) Writer {
+pub fn writer(self: *Self, buffer: []u8) Writer {
     return .{
         .console = self,
         .interface = .{
@@ -147,7 +154,10 @@ fn writer(self: *Self, buffer: []u8) Writer {
 }
 
 pub fn printf(self: *Self, comptime format: []const u8, args: anytype) void {
-    var w = self.writer(&.{});
+    var buffer: [1024]u8 = undefined;
-    w.interface.print(format, args) catch unreachable;
+    var w = self.writer(&buffer);
+    const io_w = &w.interface;
+    io_w.print(format, args) catch unreachable;
+    io_w.flush() catch unreachable;
 }
 

src/main.zig

@@ -1,21 +1,23 @@
 const lazy = @import("utils/Lazy.zig").lazy;
 const Console = @import("Console.zig");
+const MultibootInfo = @import("multiboot.zig").Info;
+
+const MultibootHeader = packed struct {
+    magic: i32,
+    flags: i32,
+    checksum: i32,
+    padding: u32,
+};
 
 const ALIGN = 1 << 0;
 const MEMINFO = 1 << 1;
 const MAGIC = 0x1BADB002;
 const FLAGS = ALIGN | MEMINFO;
-
-const MultibootHeader = packed struct {
-    magic: i32 = MAGIC,
-    flags: i32,
-    checksum: i32,
-    padding: u32 = 0,
-};
-
 export var mutliboot: MultibootHeader align(4) linksection(".multiboot") = .{
+    .magic = MAGIC,
     .flags = FLAGS,
     .checksum = -(MAGIC + FLAGS),
+    .padding = 0,
 };
 
 var stack_bytes: [16 * 1024]u8 align(16) linksection(".bss") = undefined;
@@ -24,6 +26,8 @@ export fn _start() callconv(.naked) noreturn {
     asm volatile (
         \\ movl %[stack_top], %%esp
         \\ movl %%esp, %%ebp
+        \\ push %%ebx
+        \\ push %%eax
         \\ call %[kmain:P]
         :
         : [stack_top] "i" (@as([*]align(16) u8, @ptrCast(&stack_bytes)) + @sizeOf(@TypeOf(stack_bytes))),
@@ -33,13 +37,23 @@ export fn _start() callconv(.naked) noreturn {
 
 var console = lazy(Console, .init);
 
-fn kmain() callconv(.c) void {
+fn kmain(magic: u32, info: *const MultibootInfo) callconv(.c) void {
-    std.log.info("This is an info message", .{});
+    std.debug.assert(magic == MAGIC);
-    std.log.debug("This is a debug message!", .{});
-    std.log.warn("This is a warning message!", .{});
-    std.log.err("This is an error message!", .{});
 
-    @panic("Uh oh");
+    std.log.info("{any}", .{info});
+
+    if (info.isValid(.boot_loader_name)) {
+        std.log.info("Booted by {s}", .{info.boot_loader_name});
+    }
+    if (info.isValid(.cmdline)) {
+        std.log.info("Booted with cmdline \"{s}\"", .{info.cmdline});
+    }
+
+    hang();
+}
+
+fn hang() noreturn {
+    while (true) asm volatile ("hlt");
 }
 
 const std = @import("std");
@@ -51,7 +65,7 @@ fn kpanic(msg: []const u8, first_trace_addr: ?usize) noreturn {
 
     std.log.err("PANIC: {s}", .{msg});
 
-    while (true) {}
+    hang();
 }
 
 pub const std_options = std.Options{
@@ -73,13 +87,11 @@ fn klog(
         .info => Console.ConsoleColor.light_blue,
         .debug => Console.ConsoleColor.light_green,
     };
-    c.putChar('[');
-    {
-        c.setColor(color, Console.ConsoleColor.black);
-        defer c.resetColor();
 
-        c.puts(level.asText());
+    c.putChar('[');
-    }
+    c.setColor(color, Console.ConsoleColor.black);
+    c.puts(level.asText());
+    c.resetColor();
     c.putChar(']');
 
     c.putChar(' ');
@@ -90,4 +102,3 @@ fn klog(
 
     c.printf(format ++ "\n", args);
 }
-

src/multiboot.zig

@@ -1,56 +1,96 @@
-pub const Info = extern struct {
+const std = @import("std");
-    flags: c_uint,
+
-    mem_lower: c_uint,
+const BootModule = packed struct {
-    mem_upper: c_uint,
+    start: u32,
-    boot_device: c_uint,
+    end: u32,
-    cmdline: c_uint,
+    string: ?[*:0]u8,
-    mods_count: c_uint,
+    reserved: u32,
-    mods_addr: c_uint,
-    u: extern union {
-        aout_sym: extern struct {
-            tabsize: c_uint,
-            strsize: c_uint,
-            addr: c_uint,
-            reserved: c_uint,
-        },
-        elf_sec: extern struct {
-            num: c_uint,
-            size: c_uint,
-            addr: c_uint,
-            shndx: c_uint,
-        },
-    },
-    mmap_length: c_uint,
-    mmap_addr: c_uint,
-    drives_length: c_uint,
-    drives_addr: c_uint,
-    config_table: c_uint,
-    boot_loader_name: c_uint,
-    apm_table: c_uint,
-    vbe_control_info: c_uint,
-    vbe_move_info: c_uint,
-    vbe_mode: c_ushort,
-    vbe_interface_seg: c_ushort,
-    vbe_interface_off: c_ushort,
-    vbe_interface_len: c_ushort,
-    framebuffer_addr: c_ulonglong,
-    framebuffer_pitch: c_uint,
-    framebuffer_width: c_uint,
-    framebuffer_height: c_uint,
-    framebuffer_bpp: u8,
-    framebuffer_type: u8,
-    unnamed_0: extern union {
-        unnamed_0: extern struct {
-            framebuffer_palette_addr: c_uint,
-            framebuffer_palette_num_colors: c_ushort,
-        },
-        unnamed_1: extern struct {
-            framebuffer_red_field_position: u8,
-            framebuffer_red_mask_size: u8,
-            framebuffer_green_field_position: u8,
-            framebuffer_green_mask_size: u8,
-            framebuffer_blue_field_position: u8,
-            framebuffer_blue_mask_size: u8,
-        },
-    },
 };
+
+pub const Info = packed struct {
+    flags: std.bit_set.IntegerBitSet(32),
+    mem_lower: u32,
+    mem_upper: u32,
+    boot_device: packed struct {
+        part3: u8,
+        part2: u8,
+        part1: u8,
+        drive: u8,
+    },
+    cmdline: [*:0]u8,
+    mods_count: u32,
+    mods_addr: [*]BootModule,
+    u: packed union {
+        aout_sym: packed struct {
+            tabsize: u32,
+            strsize: u32,
+            addr: u32,
+            reserved: u32,
+        },
+        elf_sec: packed struct {
+            num: u32,
+            size: u32,
+            addr: u32,
+            shndx: u32,
+        },
+    },
+    mmap_length: u32,
+    mmap_addr: u32,
+    drives_length: u32,
+    drives_addr: u32,
+    config_table: u32,
+    boot_loader_name: [*:0]u8,
+    apm_table: u32,
+    vbe: packed struct {
+        control_info: u32,
+        move_info: u32,
+        mode: u16,
+        interface_seg: u16,
+        interface_off: u16,
+        interface_len: u16,
+    },
+    framebuffer: packed struct {
+        addr: u64,
+        pitch: u32,
+        width: u32,
+        height: u32,
+        bpp: u8,
+        type: u8,
+        color_info: packed union {
+            indexed_color: packed struct {
+                framebuffer_palette_addr: u32,
+                framebuffer_palette_num_colors: u16,
+            },
+            rgb_color: packed struct {
+                framebuffer_red_field_position: u8,
+                framebuffer_red_mask_size: u8,
+                framebuffer_green_field_position: u8,
+                framebuffer_green_mask_size: u8,
+                framebuffer_blue_field_position: u8,
+                framebuffer_blue_mask_size: u8,
+            },
+        },
+    },
+
+    const Self = @This();
+
+    pub fn isValid(self: *const Self, comptime field: std.meta.FieldEnum(Self)) bool {
+        return switch (field) {
+            .flags => true,
+            .mem_lower, .mem_upper => self.flags.isSet(0),
+            .boot_device => self.flags.isSet(1),
+            .cmdline => self.flags.isSet(2),
+            .mods_count, .mods_addr => self.flags.isSet(3),
+            // TODO: .u => either 4 or 5
+            .mmap_length, .mmap_addr => self.flags.isSet(6),
+            .drives_length, .drives_addr => self.flags.isSet(7),
+            .config_table => self.flags.isSet(8),
+            .boot_loader_name => self.flags.isSet(9),
+            .apm_table => self.flags.isSet(10),
+            .vbe => self.flags.isSet(11),
+            .framebuffer => self.flags.isSet(12),
+            else => false,
+        };
+    }
+};
+