Re: [Qemu-devel] [PATCH] Add resolutions via the command-line

[G 3]

On Sep 20, 2016, at 8:41 PM, Benjamin Herrenschmidt wrote:

> On Tue, 2016-09-20 at 20:35 -0400, G 3 wrote:
> > When I use the -prom-env option I can easily add properties to the
> > options node.
> > Can something like this be done with the chosen node?
>
> We can make it so. That or we can add code to OpenBIOS to copy the  
> list
> of resolutions into the device-node of the VGA device. The latter is
> probably the best, that way we can also have all the default ones in
> OpenBIOS and remove the hard coded list completely.

You really want to remove the included list of resolutions? I was  
thinking about adding a lot more built-in resolutions in another  
patch. A built-in list is very convenient.

As for the options node problem. We need a way to add resolutions  
from the command-line for a Mac OS X guest. Using "-prom-env" isn't  
an option because of some unknown bug. I suppose it is possible to  
fix this bug - if it is a bug. Another idea I have is to add a  
completely different command-line option to QEMU just for  
resolutions. The user could specify resolutions like this: -video- 
resolutions 640x480,1024x768,1280x700.... This feature could place  
the list of resolutions inside a property of the VGA device node. I  
am betting the VGA driver could access this node and parse the list  
of resolutions. So this: qemu -video-resolutions ---> OpenBIOS VGA  
device node ---> VGA driver

Would anyone have another idea they would like to share?