Libguestfs - Mar 2023 - [V2V PATCH 1/1] convert_windows: add firstboot script to install drivers with pnputil

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>
---
 convert/convert_windows.ml | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/convert/convert_windows.ml b/convert/convert_windows.ml
index 6bc2343b..e15a5e62 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 +347,16 @@ 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
>\"%~dpn0.log\" 2>&1\
+                    " in
+    Firstboot.add_firstboot_script g inspect.i_root
+      "pnputil install drivers" fb_script;
+
   and configure_wait_pnp tool_path      (* Prevent destructive interactions of
firstboot with PnP. *)
 
-- 
2.31.1

On Wed, Mar 08, 2023 at 08:05:35PM +0200, Andrey Drobyshev
wrote:
> 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>
> ---
>  convert/convert_windows.ml | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/convert/convert_windows.ml b/convert/convert_windows.ml
> index 6bc2343b..e15a5e62 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 +347,16 @@ 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
>\"%~dpn0.log\" 2>&1\
> +                    " in
> +    Firstboot.add_firstboot_script g inspect.i_root
> +      "pnputil install drivers" fb_script;
> +
I'm not sure I'm really qualified to comment on this, since Windows is
crazy.  I guess the worst this can do is fail to run, but that won't
stop anything else from happening.

Note that firstboot scripts already do logging, so I don't believe
writing to a separate log file is needed here.  All the output from
all firstboot scripts should go to
C:\Program Files\Guestfs\Firstboot\log.txt:

https://github.com/libguestfs/libguestfs-common/blob/7acf991a25b3fd625eb1ff1fbd8dc9fedf245942/mlcustomize/firstboot.ml#L276

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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