Libguestfs - Nov 2021 - [virt-v2v RFC wave 2 02/10] convert_linux: use "modesetting" X.org driver for Standard_VGA

In a Fedora 34 guest using standard VGA video, and having no explicit
X.org config file, the X.org server logs the following (excerpt):
> Markers: (--) probed, (**) from config file, (==) default setting,
>         (++) from command line, (!!) notice, (II) informational,
>         (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
> (==) Matched modesetting as autoconfigured driver 0
> (==) Matched fbdev as autoconfigured driver 1
> (==) Matched vesa as autoconfigured driver 2
> (II) LoadModule: "modesetting"
> (II) Loading /usr/lib64/xorg/modules/drivers/modesetting_drv.so
> (II) LoadModule: "fbdev"
> (II) Loading /usr/lib64/xorg/modules/drivers/fbdev_drv.so
> (II) LoadModule: "vesa"
> (II) Loading /usr/lib64/xorg/modules/drivers/vesa_drv.so
> (II) Loading sub module "fbdevhw"
> (II) LoadModule: "fbdevhw"
> (II) Loading /usr/lib64/xorg/modules/libfbdevhw.so
> (II) UnloadModule: "fbdev"
> (II) Unloading fbdev
> (II) UnloadSubModule: "fbdevhw"
> (II) Unloading fbdevhw
> (II) UnloadModule: "vesa"
> (II) Unloading vesa
This tells us that the standard VGA device model is driven by the
"modesetting" driver. Update the "configure_display_driver"
function (for
Linux guests) accordingly.

Cc: Gerd Hoffmann <kraxel at redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1961107
Signed-off-by: Laszlo Ersek <lersek at redhat.com>
---
 convert/convert_linux.ml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/convert/convert_linux.ml b/convert/convert_linux.ml
index 85d8c5ae0e92..15f68fd4f8db 100644
--- a/convert/convert_linux.ml
+++ b/convert/convert_linux.ml
@@ -831,7 +831,7 @@ let convert (g : G.guestfs) source inspect
keep_serial_console rcaps _    and configure_display_driver video      let
video_driver        match video with
-      | Standard_VGA -> assert false
+      | Standard_VGA -> "modesetting"
       | QXL -> "qxl"
       | Cirrus -> "cirrus" in
 
-- 
2.19.1.3.g30247aa5d201

Hi,
> > (II) LoadModule: "modesetting"
> > (II) LoadModule: "fbdev"
> > (II) LoadModule: "vesa"
> > (II) UnloadModule: "fbdev"
> > (II) UnloadModule: "vesa"
> This tells us that the standard VGA device model is driven by the
> "modesetting" driver. Update the
"configure_display_driver" function (for
> Linux guests) accordingly.
Correct.

Acked-by: Gerd Hoffmann <kraxel at redhat.com>
>    and configure_display_driver video >      let video_driver >      
match video with
> -      | Standard_VGA -> assert false
> +      | Standard_VGA -> "modesetting"
>        | QXL -> "qxl"
>        | Cirrus -> "cirrus" in
Oh.  More updates needed.

cirrus is modesetting too, unless you use a *really* old distro.

   kraxel at sirius ~/distgit/xorg-x11-drv-cirrus (rawhide)# cat dead.package 
   2014-07-06: retired driver, because it does not support KMS:
https://lists.fedoraproject.org/pipermail/devel/2013-August/188429.html

qxl is on a similar path.  In case xorg-x11-drv-qxl.rpm is installed
xorg will prefer the qxl driver.  In case the driver is not present xorg
will use the modesetting driver instead and it'll work equally fine.
I think RHEL-9 doesn't ship xorg-x11-drv-qxl.rpm any more.

virtio-gpu will also be handled by the modesetting driver.

So possibly you can just do 'let video_driver = "modesetting"'

take care & HTH,
  Gerd