[Libguestfs] [PATCH 2/2] v2v: remove the 'graphicsmodedisabled' entry in ESP BCD
Richard W.M. Jones
rjones at redhat.com
Fri Jun 10 15:03:42 UTC 2016
On Fri, Jun 10, 2016 at 05:07:03PM +0300, Pavel Butsykin wrote:
> Guest tools for Windows in Parallels / Virtuozzo Server 6 contain a
> paravirtualized video driver, which wants to take full control of the video
> mode. To avoid excessive video mode switches in UEFI VMs it executes
> "bcdedit /set {current} graphicsmodedisabled true".
>
> When such a VM is imported into a QEMU/KVM-based hypervisor, the
> standard video drivers in Windows do not set the video mode as they
> expect it to have already been configured by the bootloader. As a result,
> the VM runs with black screen.
>
> So patch the BCD store (which is a Windows registry hive with a special
> structure, located on the EFI system partition) to clear this setting.
>
> Signed-off-by: Pavel Butsykin <pbutsykin at virtuozzo.com>
> ---
> v2v/convert_windows.ml | 41 +++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 41 insertions(+)
>
> diff --git a/v2v/convert_windows.ml b/v2v/convert_windows.ml
> index 62bb536..8579240 100644
> --- a/v2v/convert_windows.ml
> +++ b/v2v/convert_windows.ml
> @@ -466,6 +466,45 @@ if errorlevel 3010 exit /b 0
> ignore (g#pwrite_device rootpart bytes 0x1a_L)
> )
> )
> +
> + and fix_win_esp () =
> + let fix_win_uefi_bcd esp_path =
> + try
> + let bcd_path = "/EFI/Microsoft/Boot/BCD" in
> + Windows.with_hive_write g (esp_path ^ bcd_path) (
> + (* Remove the 'graphicsmodedisabled' key in BCD *)
> + fun root ->
> + let path = ["Objects"; "{9dea862c-5cdd-4e70-acc1-f32b344d4795}";
> + "Elements"; "23000003"] in
> + let boot_mgr_default_link =
> + match Windows.get_node g root path with
> + | None -> raise Not_found
> + | Some node -> node in
> + let current_boot_entry = g#hivex_value_utf8 (
> + g#hivex_node_get_value boot_mgr_default_link "Element") in
> + let path = ["Objects"; current_boot_entry; "Elements"; "16000046"] in
> + match Windows.get_node g root path with
> + | None -> raise Not_found
> + | Some graphics_mode_disabled ->
> + g#hivex_node_delete_child graphics_mode_disabled
> + );
> + with
> + Not_found -> ()
> + in
> +
> + let esp_temp_path = g#mkdtemp "/Windows/Temp/ESP_XXXXXX" in
> +
> + match inspect.i_uefi with
> + | None -> ()
> + | Some uefi_list ->
> + List.iter (
> + fun dev_path ->
> + g#mount dev_path esp_temp_path;
> + fix_win_uefi_bcd esp_temp_path;
> + g#umount esp_temp_path;
> + ) uefi_list;
> +
> + g#rmdir esp_temp_path;
> in
>
> (* Firstboot configuration. *)
> @@ -480,6 +519,8 @@ if errorlevel 3010 exit /b 0
>
> fix_ntfs_heads ();
>
> + fix_win_esp ();
> +
This patch looks OK to me.
Thanks,
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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