diff --git a/.cargo/config.toml b/.cargo/config.toml
index 652c4cb..35049cb 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -1,5 +1,2 @@
-[build]
-target = "aarch64-unknown-uefi"
-
 [alias]
 xtask = "run --package xtask --"
diff --git a/Cargo.lock b/Cargo.lock
index deef902..98a9981 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -110,6 +110,7 @@ checksum = "7059fff8937831a9ae6f0fe4d658ffabf58f2ca96aa9dec1c889f936f705f216"
 name = "efigife"
 version = "0.1.0"
 dependencies = [
+ "byteorder",
  "embedded-graphics",
  "tinygif",
  "uefi",
diff --git a/Cargo.toml b/Cargo.toml
index acfb009..b79150b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,3 +2,12 @@
 members = ["efi-bin", "xtask"]
 resolver = "2"
 
+[profile.release]
+strip = true
+opt-level = "z"
+lto = true
+codegen-units = 1
+panic = "abort"
+
+[workspace.dependencies]
+byteorder = { version = "*", default-features = false }
diff --git a/efi-bin/Cargo.toml b/efi-bin/Cargo.toml
index 05fcc4c..fd6e1e1 100644
--- a/efi-bin/Cargo.toml
+++ b/efi-bin/Cargo.toml
@@ -6,14 +6,8 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+byteorder.workspace = true
 embedded-graphics = "0.8.1"
 tinygif = { version = "0.0.4", features = ["8k"] }
 uefi = { version = "0.28.0", features = ["global_allocator", "panic_handler", "alloc"] }
 uefi-graphics2 = "0.1.3"
-
-[profile.release]
-strip = true
-opt-level = "z"
-lto = true
-codegen-units = 1
-panic = "abort"
diff --git a/xtask/src/main.rs b/xtask/src/main.rs
index ca82811..47b803e 100644
--- a/xtask/src/main.rs
+++ b/xtask/src/main.rs
@@ -5,10 +5,10 @@ use std::{
     process::{Command, Stdio},
 };
 
-use fatfs::{FileSystem, FsOptions};
+use fatfs::{FileSystem, FormatVolumeOptions, FsOptions};
 
 fn main() {
-    let mut args: VecDeque<_> = std::env::args().collect();
+    let mut args: VecDeque<_> = std::env::args().skip(1).collect();
 
     match args.pop_front() {
         Some(cmd) => match cmd.as_str() {
@@ -16,26 +16,32 @@ fn main() {
             "run" => do_run(args),
             x => eprintln!("unknown command {:?}", x),
         },
-        None => eprintln!("usage: cargo xtask [build|run]"),
+        None => eprintln!("usage: cargo xtask [build|run] [x86_64|aarch64]"),
     }
 }
 
 fn do_build(mut args: VecDeque<String>) {
-    let mut cmd = Command::new(env!("CARGO"));
-    cmd.arg("build")
+    let build_success = Command::new(env!("CARGO"))
+        .arg("build")
         .arg("--bin")
-        .arg("efi-bin")
-        .arg("--release") // TODO: target according to arg
+        .arg("efigife")
+        .arg("--release")
+        .arg("--target")
+        .arg("aarch64-unknown-uefi") // TODO: target according to arg
         .stdin(Stdio::inherit())
         .stdout(Stdio::inherit())
         .stderr(Stdio::inherit())
         .output()
-        .unwrap();
+        .unwrap()
+        .status
+        .success();
+    assert!(build_success);
 
     let efi_bin_path = concat!(
         env!("CARGO_MANIFEST_DIR"),
-        "/target/aarch64-unknown-uefi/efi-bin.efi"
+        "/../target/aarch64-unknown-uefi/release/efigife.efi"
     );
+    eprintln!("{}", efi_bin_path);
     let mut efi_bin_buf = Vec::new();
     let mut efi_bin_file = File::open(efi_bin_path).unwrap();
     let efi_bin_size = efi_bin_file.read_to_end(&mut efi_bin_buf);
@@ -44,7 +50,12 @@ fn do_build(mut args: VecDeque<String>) {
     let fat_disk_size = 256 * 1024; // todo!("get size from efi_bin_size");
 
     let mut fat_disk = Cursor::new(vec![0; fat_disk_size]);
-    let mut fat_fs = FileSystem::new(&mut fat_disk, FsOptions::new()).unwrap();
+    fatfs::format_volume(
+        &mut fat_disk,
+        FormatVolumeOptions::new().fat_type(fatfs::FatType::Fat12),
+    )
+    .unwrap();
+    let fat_fs = FileSystem::new(&mut fat_disk, FsOptions::new()).unwrap();
     let boot_efi_name = "BOOTAA64.EFI"; // TODO: parameterize on arg
     let mut boot_efi = fat_fs
         .root_dir()
@@ -55,12 +66,12 @@ fn do_build(mut args: VecDeque<String>) {
         .create_file(boot_efi_name)
         .unwrap();
 
-    boot_efi.write_all(&efi_bin_buf);
+    boot_efi.write_all(&efi_bin_buf).unwrap();
     drop(boot_efi);
     fat_fs.unmount().unwrap();
 
     // TODO: do the gif format juggling to add the comment in this xtask
-    let src_gif_path = concat!(env!("CARGO_MANIFEST_DIR"), "/efi-bin/src/bad-apple.gif");
+    let src_gif_path = concat!(env!("CARGO_MANIFEST_DIR"), "/../efi-bin/src/bad-apple.gif");
     let mut src_gif_file = File::open(src_gif_path).unwrap();
     let mut buf = Vec::new();
     let src_gif_size = src_gif_file.read_to_end(&mut buf).unwrap();
@@ -68,9 +79,17 @@ fn do_build(mut args: VecDeque<String>) {
     let fat_start_sector = (src_gif_size + 511) / 512;
     buf.extend(std::iter::repeat(0).take(fat_start_sector * 512 - buf.len()));
     buf.extend(fat_disk.into_inner());
+
+    let out_img_path = format!(
+        "{}/../target/bad-apple.{}-efi.raw.gif",
+        env!("CARGO_MANIFEST_DIR"),
+        "aarch64"
+    );
+    let mut out_img_file = File::create(out_img_path).unwrap();
+    out_img_file.write_all(&buf).unwrap();
 }
 
-fn do_run(mut args: VecDeque<String>) {
+fn do_run(args: VecDeque<String>) {
     do_build(args.clone());
 
     let mut cmd = match args[0].as_str() {
@@ -89,12 +108,17 @@ fn do_run(mut args: VecDeque<String>) {
             cmd
         }
         "x86_64" | "x64" => {
-            let mut cmd = Command::new("qemu-system-x86_64");
+            //let mut cmd = Command::new("qemu-system-x86_64");
             todo!();
         }
         x => unimplemented!("target cpu {:?}", x),
     };
-    cmd.arg(todo!("disk image"))
+    let out_img_path = format!(
+        "{}/../target/bad-apple.{}-efi.raw.gif",
+        env!("CARGO_MANIFEST_DIR"),
+        "aarch64"
+    );
+    cmd.arg(out_img_path)
         .stdin(Stdio::inherit())
         .stdout(Stdio::inherit())
         .stderr(Stdio::inherit())