Re: [RFC] enhancing the kernel's graphics subsystem

[Dave Airlie]

On 5/21/07, Jon Smirl <jonsmirl@xxxxxxxxx> wrote:
> On 5/21/07, Dave Airlie <airlied@xxxxxxxxx> wrote:
> > This just needs a userspace console again a parallel problem that
> > really isn't much to do with the problem set this work is trying to
> > solve... it should enable it...
>
> When I went through the design process for all this I came to the same
> conclusion about needing a user space console process.
>
> User space console does impact on all of this because it implies that
> the current console should be be defeatured down until it becomes only
> a system recovery console and not a console for everyday use.
>
> For example, one part of the defeaturing would be to remove the
> drawing acceleration code in the existing fbdev console drivers and to
> rework it to support accelerated drawing from the user space console
> implementation. You want the system recovery console mode to be as
> simple as possible so that it is always guaranteed to work. User space
> console is also what leads to the idea of compiling VT out of the
> kernel.
>
> Once you decide that a user space console is needed then the per CRTC
> device node becomes more obvious since different people can be logged
> onto the different consoles.
>
> All of the points in the list are interrelated and the architecture
> needs to address everything as a unified whole.

you were doing fine up until the last point, they are interrelated but
not architecturally dependent, we can do a lot of work on this stuff
without that, we don't need to deprecate anything, just provide new
interfaces that new drivers can use to implement this stuff, then
people can pull over the old drivers at their own pace, like we can
just stick a flag in the console that says we can handle things like
dumping oopsen in KD_GRAPHICS etc.. drivers that can do it will do it,
drivers that can't won't.

You don't compile VT out you just disable it when you have a driver
that supports the model,

You also require a heavy weight state switch for suspend/resume in any
case so this could be utilised for other things, e.g. text mode on
many cards can't be done while acceleration is operational, but
certainly don't want to bar text mode for people who want it..

Dave.
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