feat(loader, kernel): impl part of loader and initialize kernel structure

arch/x86_64/boot/build_tool/generate_image.zig

@@ -0,0 +1,50 @@
+const std = @import("std");
+const Dir = std.Io.Dir;
+const ALIGN_SIZE: usize = 4096;
+pub fn main(init: std.process.Init) !void {
+    const args = try init.minimal.args.toSlice(init.arena.allocator());
+    if (args.len != 4) {
+        std.debug.print("Usage: {s} <header_file> <kcapsule_file> <output_file>\n", .{args[0]});
+        std.process.exit(1);
+    }
+    const header_path = args[1];
+    const kcapsule_path = args[2];
+    const output_path = args[3];
+    var image = try Dir.cwd().createFile(init.io, output_path, .{ .truncate = true });
+    defer image.close(init.io);
+
+    var image_buffer: [4096]u8 = undefined;
+    var w = image.writer(init.io, &image_buffer);
+    var read_buffer: [4096]u8 = undefined;
+
+    const header_file = try Dir.cwd().openFile(init.io, header_path, .{});
+    var r = header_file.reader(init.io, &[0]u8{});
+    var written: usize = 0;
+    while (true) {
+        const read_bytes = try r.interface.readSliceShort(&read_buffer);
+        if (read_bytes == 0) break;
+        try w.interface.writeAll(read_buffer[0..read_bytes]);
+        written += read_bytes;
+    }
+    header_file.close(init.io);
+
+    if (written % ALIGN_SIZE != 0) {
+        var padding_size = ALIGN_SIZE - (written % ALIGN_SIZE);
+        @memset(read_buffer[0..@min(padding_size, read_buffer.len)], 0);
+        while (padding_size > 0) {
+            const to_write = @min(padding_size, read_buffer.len);
+            try w.interface.writeAll(read_buffer[0..to_write]);
+            padding_size -= to_write;
+        }
+    }
+    const kcapsule_file = try Dir.cwd().openFile(init.io, kcapsule_path, .{});
+    r = kcapsule_file.reader(init.io, &[0]u8{});
+    while (true) {
+        const read_bytes = try r.interface.readSliceShort(&read_buffer);
+        if (read_bytes == 0) break;
+        try w.interface.writeAll(read_buffer[0..read_bytes]);
+        written += read_bytes;
+    }
+    kcapsule_file.close(init.io);
+    try w.interface.flush();
+}