Make --install-from-img take no file; derive it from the ISO path

--install-from-img now works like --install-from-iso: the installation
media is the ISO path (WIN11_VM_INSTALL_ISO or the downloader's) with
.install.img in place of .iso, which is where
build-windows-install-disk.sh writes it by default. Drop the FILE argument
and WIN11_VM_INSTALL_IMG.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

run-windows11.py

@@ -126,14 +126,14 @@ else:
     )
 daemonize = False
 install_from_iso = False
-install_img = Path(env("WIN11_VM_INSTALL_IMG")) if env("WIN11_VM_INSTALL_IMG") else None
+install_from_img = False
 download_only = False
 extra_args = []
 
 
 def usage(stream=sys.stdout):
     stream.write(f"""\
-Usage: {Path(sys.argv[0]).name} [--daemon] [--download-only] [--install-from-iso | --install-from-img FILE]
+Usage: {Path(sys.argv[0]).name} [--daemon] [--download-only] [--install-from-iso | --install-from-img]
        [--state-dir DIR] [--rdp-port PORT] [--ssh-port PORT] [-- QEMU_ARGUMENT ...]
 
 If the system disk (DIR/disk.qcow2, see --state-dir) is missing, create it from
@@ -151,12 +151,11 @@ Options:
   --download-only     Download the VirtIO tools ISO if it is missing, then exit
                       (the Windows ISO and base QCOW2 are supplied manually)
   --install-from-iso  Install from ISO when the system disk is missing
-  --install-from-img FILE
+  --install-from-img  Like --install-from-iso, but install from the disk image
-                      Install from a disk image made by
+                      made by vm-images/build-windows-install-disk.sh, which
-                      vm-images/build-windows-install-disk.sh instead of the ISO
+                      is the ISO path ending in .install.img instead of .iso.
-                      (implies --install-from-iso). It is attached as an NVMe
+                      It is attached as an NVMe disk, much faster than the
-                      disk, much faster than the emulated USB CD-ROM, and is
+                      emulated USB CD-ROM, and is never modified
-                      never modified (overrides WIN11_VM_INSTALL_IMG)
   --state-dir DIR     Directory for the VM disk, seed ISO and runtime files
                       (default: .vm/windows11; overrides WIN11_VM_STATE_DIR)
   --rdp-port PORT     Host port forwarded to guest RDP (default: 3389;
@@ -168,7 +167,7 @@ Options:
 Environment variables:
   WIN11_VM_BASE_IMAGE   Windows 11 base QCOW2 image (default: beside shared images)
   WIN11_VM_INSTALL_ISO  Windows 11 installation ISO used with --install-from-iso
-  WIN11_VM_INSTALL_IMG  Installation disk image used instead of the ISO
+                        (--install-from-img uses the same path ending in .install.img)
   WIN11_VM_TOOLS_ISO    VirtIO Windows tools ISO (default: resolved by shared image helper)
   WIN11_VM_RDP_PORT     Host RDP port (default: 3389)
   WIN11_VM_SSH_PORT     Host SSH port (default: 2222)
@@ -194,11 +193,7 @@ while args:
     elif arg == "--install-from-iso":
         install_from_iso = True
     elif arg == "--install-from-img":
-        if not args:
+        install_from_img = True
-            die(f"{arg} requires a file argument.", 2)
-        install_img = Path(args.pop(0))
-    elif arg.startswith("--install-from-img="):
-        install_img = Path(arg.split("=", 1)[1])
     elif arg == "--state-dir":
         if not args:
             die(f"{arg} requires a directory argument.", 2)
@@ -228,7 +223,7 @@ while args:
         usage(sys.stderr)
         sys.exit(2)
 
-if install_img:
+if install_from_img:
     install_from_iso = True
 
 if download_only:
@@ -263,10 +258,11 @@ if not disk_image.is_file():
     installing_from_iso = install_from_iso
     image_downloader = find_image_downloader()
     if install_from_iso:
-        # The installation disk image replaces the ISO, which is then not needed.
+        install_iso = Path(
-        install_iso = None if install_img else Path(
             env("WIN11_VM_INSTALL_ISO")
             or capture([str(image_downloader), "--print-path", "windows11", "--iso"]))
+        if install_from_img:
+            install_iso = install_iso.with_suffix(".install.img")
         uses_shared_tools_iso = False
         if env("WIN11_VM_TOOLS_ISO"):
             tools_iso = Path(env("WIN11_VM_TOOLS_ISO"))
@@ -282,12 +278,11 @@ if shutil.which(qemu_binary) is None:
 if installing:
     if shutil.which("qemu-img") is None:
         die("qemu-img is not installed.")
-    if install_img:
+    if installing_from_iso:
-        if not install_img.is_file():
-            die(f"Windows 11 installation disk image was not found: {install_img}\n"
-                "Build it with vm-images/build-windows-install-disk.sh ISO OUTPUT.img")
-    elif installing_from_iso:
         if not install_iso.is_file():
+            if install_from_img:
+                die(f"Windows 11 installation disk image was not found: {install_iso}\n"
+                    "Build it with vm-images/build-windows-install-disk.sh ISO")
             die(f"Windows 11 ISO was not found: {install_iso}")
     elif not base_image.is_file():
         die(f"Windows 11 base QCOW2 image was not found: {base_image}")
@@ -399,12 +394,12 @@ if installing_from_iso:
         device = (f"ide-cd,drive={media_id},bus={ide_bus},bootindex={boot_index}"
                   if host_arch == "amd64"
                   else f"usb-storage,drive={media_id},bootindex={boot_index}")
-        if media_id == "install_media" and install_img:
+        if media_id == "install_media" and install_from_img:
             # snapshot=on: NVMe cannot report write protection, and Windows
             # writes to the volume it mounts, so a read-only drive makes it fail.
             # The writes go to a temporary overlay and the image stays unchanged.
             qemu_args += [
-                "-drive", f"file={install_img},if=none,id={media_id},format=raw,snapshot=on",
+                "-drive", f"file={media_file},if=none,id={media_id},format=raw,snapshot=on",
                 "-device", f"nvme,drive={media_id},serial=installer,bootindex={boot_index}",
             ]
             continue

windows11-arm64-install-speed.md

@@ -8,7 +8,7 @@
 - 慢的原因是**安装介质走了模拟的 USB 光驱**（`usb-storage` 挂 ISO）：读安装文件平均只有约 4 MB/s。
 - 把安装介质改成**FAT32 分区里的 NVMe 磁盘镜像**（`install.wim` 拆成 `.swm`）后，读速达到 54 到 92 MB/s
   （前 7 个采样平均约 74 MB/s），安装在约 80 秒内到 40%，复制阶段约 2 分钟结束。
-- 方案已接进 `run-windows11.py`：`--install-from-img FILE`，镜像由 `vm-images/build-windows-install-disk.sh` 生成。
+- 方案已接进 `run-windows11.py`：`--install-from-img`，镜像由 `vm-images/build-windows-install-disk.sh` 生成。
 
 ## 环境
 
@@ -100,11 +100,12 @@ vm-images/build-windows-install-disk.sh [--force] ISO [OUTPUT.img]
 
 ### 启动方式
 
-`run-windows11.py` 的 `--install-from-img FILE`（或环境变量 `WIN11_VM_INSTALL_IMG`）用这个镜像做安装介质，隐含 `--install-from-iso`，
+`run-windows11.py` 的 `--install-from-img` 用这个镜像做安装介质，隐含 `--install-from-iso`。镜像路径是 ISO 路径
-此时不再需要找 ISO：
+（`WIN11_VM_INSTALL_ISO` 或自动查找到的 ISO）把 `.iso` 换成 `.install.img`，也就是 `build-windows-install-disk.sh ISO` 默认生成的位置，
+此时不再读取 ISO：
 
 ```bash
-./run-windows11.py --install-from-img vm-images/install-iso/Windows11_Client_arm64_en-us_26300_9457.install.img
+./run-windows11.py --install-from-img
 ```
 
 `install_media` 不再作为 `usb-storage` 光驱，而是：