Re: [SeaBIOS] [PATCH] don't expose pvpanic device in the UI

[Michael S. Tsirkin]

On Mon, Aug 05, 2013 at 03:47:23PM +0800, Hu Tao wrote:
> pvpanic device is an internal default device in qemu. It may cause
> problem when upgrading qemu from a version without pvpanic.
>
> for example: in Windows(let's say XP) the Device manager will open a
> "new device" wizard and the device will appear as an unrecognized
> device.  On a cluster with hundreds of such VMs, If that cluster has
> a health monitoring service it may show all the VMs in a "not healthy"
> state.
>
> This patch is a workaround to not show pvpanic in UI to avoid the
> problem in Windows.
>
> Cc: Marcel Apfelbaum 
> Cc: "Michael S. Tsirkin" 
> Cc: Paolo Bonzini 
> Cc: Gerd Hoffmann 
> Cc: Eric Blake 
> Cc: "Daniel P. Berrange" 
> Cc: Andreas Färber 
> Signed-off-by: Hu Tao

Quoting from this discussion:
    >That may "fix" the issue of a windows guest showing the yellow ! mark,
    >but what if, down the road, someone writes an actual windows driver that
    >is aware of that port and how to make a windows BSOD write a panic
    >notification to the port?  How does a user go about installing such a
    >driver if the device is not exposed in the user interface list of
    >devices?

I think the correct way to address this is:
- don't create the device by default, only when -device pvpanic is
  present
- teach management to supply said -device pvpanic for guests which
  support the pvpanic device
> See discussion at: http://lists.nongnu.org/archive/html/qemu-devel/2013-08/msg00036.html
> and follow-ups.
>
> src/ssdt-misc.dsl | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/ssdt-misc.dsl b/src/ssdt-misc.dsl
> index acc850e..19a2058 100644
> --- a/src/ssdt-misc.dsl
> +++ b/src/ssdt-misc.dsl
> @@ -75,7 +75,7 @@ DefinitionBlock ("ssdt-misc.aml", "SSDT", 0x01, "BXPC", "BXSSDTSUSP", 0x1)
>                  If (LEqual(Local0, Zero)) {
>                      Return (0x00)
>                  } Else {
>                Return (0x0F)
>                Return (0x0B)
>            }
>        }