BIOS mirroring mode
alexdeucher at gmail.com
Tue Sep 16 14:47:18 PDT 2008
On Sat, Sep 6, 2008 at 7:24 PM, Protas Oleksiy <elfy.ua at gmail.com> wrote:
> Hi, guys,
> Sorry for bothering that often but I need an advice from low-level X coders,
> because surfing the net only gave userish results. Let me outline the problem.
> We have a laptop with 1280x800 native resolution. It gets connected to
> projector with a 1024x768 resolution. What I need is a cloned display. RandR
> plays fine but there is a tricky thing. Because 1024x768 is smaller than
> 1280x800, the projector only displays a portion of the screen, not the whole.
> Setting 1024x768 on built-in LCD is a no-go, because it messes plasma
> workspace and looks awful on non-native resolution.
> Now the question part. When the laptop goes up it uses BIOS to mirror the
> display output onto external VGA channel. It handles all rescaling tasks, etc.
> In Linux it is true up to X start, because the driver disables this ability
> and manages VGA output on its own.
> I am wondering how can one enable this feature on a running X server? This
> *must* be possible, as Windows keeps this thing upon boot to GUI if the
> desktop is not expanded.
> Could you hint me how this can be achieved or what needs to be coded in order
Depending on your laptop, if the driver is randr 1.2 enabled, this
should just work. Most randr-enabled X drivers can handle scaling and
centering of panels as well. What the bios does depends on the
vendor. It probably uses the scaler for the panel.
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