[Libguestfs] [V2V PATCH v4 1/2] convert_windows: add firstboot script to install drivers with pnputil

[Andrey Drobyshev]

During conversion we copy the necessary drivers to the directory
"%systemroot%\Drivers\Virtio", adding it to the DevicePath registry
value.  As documented in [1], this should be enough for Windows to find
device drivers and successfully install them.

However, it doesn't always happen.  Commit 73e009c04 ("v2v: windows:
Document use of pnputil to install drivers.") describes such issues with
Win2k12R2.  I'm seeing the same problem with Win2k16 and netkvm.sys
driver not being installed.

That same commit 73e009c04 suggests adding a firstboot script invoking
pnputil at an early stage to install all the drivers we put into the
drivers store.  So let's add such a script to make sure all the
necessary drivers are installed.

[1] https://learn.microsoft.com/en-us/windows-hardware/drivers/install/how-windows-selects-a-driver-for-a-device

Signed-off-by: Andrey Drobyshev <andrey.drobyshev at virtuozzo.com>
Acked-by: Laszlo Ersek <lersek at redhat.com>
---
 convert/convert_windows.ml | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/convert/convert_windows.ml b/convert/convert_windows.ml
index b5dc06ed..a269a50e 100644
--- a/convert/convert_windows.ml
+++ b/convert/convert_windows.ml
@@ -295,9 +295,11 @@ let convert (g : G.guestfs) _ inspect i_firmware block_driver _ static_ips =
     | Virt -> Virt
 
   and configure_firstboot () =
-    (* Note that pnp_wait.exe must be the first firstboot script as it
-     * suppresses PnP for all following scripts.
+    (* Run the firstboot script with pnputil.exe before the one with
+     * pnp_wait.exe as the latter suppresses PnP for all following scripts.
      *)
+    configure_pnputil_install ();
+
     let tool_path = virt_tools_data_dir () // "pnp_wait.exe" in
     if Sys.file_exists tool_path then
       configure_wait_pnp tool_path
@@ -345,6 +347,17 @@ let convert (g : G.guestfs) _ inspect i_firmware block_driver _ static_ips =
                       strkey name value
     | None -> sprintf "reg delete \"%s\" /v %s /f" strkey name
 
+  and configure_pnputil_install () =
+    let fb_script = "@echo off\n\
+                     \n\
+                     echo Wait for VirtIO drivers to be installed\n\
+                     %systemroot%\\Sysnative\\PnPutil -i -a \
+                     %systemroot%\\Drivers\\Virtio\\*.inf" in
+
+    (* Set priority higher than that of "v2vnetcf.ps1" firstboot script. *)
+    Firstboot.add_firstboot_script g inspect.i_root ~prio:2000
+      "pnputil install drivers" fb_script;
+
   and configure_wait_pnp tool_path =
     (* Prevent destructive interactions of firstboot with PnP. *)
 
-- 
2.31.1