[Intel-gfx] KMS breaks console

Jesse Barnes jbarnes at virtuousgeek.org
Tue Feb 3 20:31:49 CET 2009

On Tuesday, February 3, 2009 11:26 am Lukas Hejtmanek wrote:
> On Tue, Feb 03, 2009 at 10:35:40AM -0800, Jesse Barnes wrote:
> > > does this mean that oldschool text console is no longer supported as
> > > long as KMS is stream? Too bad I think.
> >
> > Once you go into a graphics mode, yes.  Why too bad?
> maybe because the text mode is more stable and seems to be much faster at
> lower CPU utilization?

Not sure about stable; that's more a function of what else the GPU is doing at 
the time (just so happens text mode is only active when nothing else is going 
on atm).

Faster & less CPU, yes.  Though there's lots of room for improvement here in 
the kms i915 fb driver.  Or you could run a standalone console program (think 
gnome-terminal ported to kms) and optimize that instead.

The problem with text mode is that it precludes us from doing much else with 
the graphics hardware.  We'd have to shut down any running queues, remove all 
our GTT binding and basically quiesce the GPU to get back.  That wouldn't 
play well with GPGPU apps or multiple graphics apps running, so thus far 
we've chosen not to allow it when KMS is active (since GPGPU and multiple 
graphics apps were two motivations behind KMS in the first place).

Jesse Barnes, Intel Open Source Technology Center

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