Re: [linux-pm] [PATCH] PM / i915: Skip kernel VT switch duringsuspend/resume if KMS is used

From: Pavel Machek
Date: Sun Jan 31 2010 - 03:54:39 EST

On Thu 2010-01-28 00:07:51, Stefan Seyfried wrote:
> Hi,
> On Tue, 26 Jan 2010 15:58:43 +0100 Pavel Machek <pavel@xxxxxx> wrote:
> > We need vt switch when display is controlled by userland app directly
> > accessing hw. It may or may not be X (svgalib anyone?,
> > gtk-on-framebuffer? qtopia?).
> anything-on-framebuffer should not be different from plain framebuffer
> console, or am I missing something?

It is. At least svgalib accesses hw directly. It probably can run even
on framebuffer.

> > Ideally, userspace should explicitely tell us. KD_KERNEL_GRAPHICS
> > console mode?
> >
> > Plus the switch is needed for any graphics app using fbcon -- I do not
> > think we actually save the framebuffer over suspend. (This one should
> > probably be fixed).
> Framebuffer should be easy to fix - it works pretty well already
> because apparently the fbcon code needs to "shadow buffer" all VT
> "windows" anyway - so maybe it's just the issue of doing an additional
> "redraw()" somewhere appropriate.

Well, for now the "shadow buffer" contains only text, not graphics
images. So you'd need to enlarge it a lot. Doable but more than one liner.

(cesky, pictures)
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