Skip kernel-irqchip=off when installing with --install-from-img

Move the setting from qemu/windows11-darwin-arm64.ini to a -machine option
that run-windows11.py adds on macOS arm64 unless --install-from-img is given.
The workaround is only needed for usb-storage, which the NVMe install disk
does not use, and Setup hangs with the emulated interrupt controller.

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

qemu/windows11-darwin-arm64.ini

@@ -7,13 +7,10 @@
 [accel]
   accel = "tcg"
 
-# With the HVF in-kernel GICv3, QEMU's usb-storage races on the status packet
+# run-windows11.py adds kernel-irqchip=off unless installing with
-# and Windows Setup stalls 10 s after every burst of reads (utmapp/UTM#7970),
+# --install-from-img (see there).
-# so use the emulated interrupt controller; upstream QEMU only gets the fix
-# from the UTM fork.
 [machine]
   type = "virt"
-  kernel-irqchip = "off"
 
 # The "virt" machine has no IDE. NVMe and USB mass storage (used by the
 # installation media of --install-from-iso) both have inbox Windows drivers.

run-windows11.py

@@ -461,6 +461,14 @@ qemu_args += [
     "-display", display_backend,
     # "-display", "none", "-spice", "port=5900,addr=127.0.0.1,disable-ticketing=on,agent-mouse=off", "-device", "virtio-vga",
 ]
+if host_os == "darwin" and host_arch == "arm64" and not install_from_img:
+    # With the HVF in-kernel GICv3, QEMU's usb-storage races on the status
+    # packet and Windows Setup stalls 10 s after every burst of reads
+    # (utmapp/UTM#7970), so use the emulated interrupt controller; upstream
+    # QEMU only gets the fix from the UTM fork. The NVMe install disk of
+    # --install-from-img does not use usb-storage, and hangs with the emulated
+    # controller.
+    qemu_args += ["-machine", "kernel-irqchip=off"]
 if installing_from_iso:
     # q35 has IDE for the installation media; "virt" does not, so use USB.
     for media_id, media_file, boot_index, ide_bus in (

windows11-arm64-install-speed.md

@@ -6,7 +6,7 @@
 ## 结论
 
 - **根因（第五节）**：HVF 的内核态 GICv3 与 QEMU 的 `usb-storage` 有竞态，Windows Setup 每读一批数据就卡约 10 秒。
-  在 `[machine]` 里加 `kernel-irqchip = "off"`（已写入 `qemu/windows11-darwin-arm64.ini`）后，
+  由 `run-windows11.py` 加 `-machine kernel-irqchip=off`（`--install-from-img` 时不加）后，
   **同样走 USB 光驱的 `--install-from-iso` 也变快了**，和 UTM 的速度一致。
 - 下面第一到五节是更早的分析：当时把慢归因于"模拟 USB 光驱吞吐低"（平均约 4 MB/s），
   这个归因不准确，真实原因是上面的 10 秒停顿；那时测到的低吞吐就是停顿拉低的平均值。