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From: Pavel Machek <pavel@ucw.cz>
To: Jordan Crouse <jordan.crouse@amd.com>
Cc: Jim Gettys <jg@laptop.org>, "Brown, Len" <len.brown@intel.com>,
	Linux Kernel ML <linux-kernel@vger.kernel.org>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	ACPI ML <linux-acpi@vger.kernel.org>,
	Adam Belay <abelay@novell.com>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
	Arjan van de Ven <arjan@linux.intel.com>,
	devel@laptop.org, Bjorn Helgaas <bjorn.helgaas@hp.com>
Subject: Re: ACPI: Idle Processor PM Improvements
Date: Thu, 14 Sep 2006 11:20:49 +0200	[thread overview]
Message-ID: <20060914092049.GB15102@elf.ucw.cz> (raw)
In-Reply-To: <20060912201805.GK14885@cosmic.amd.com>

On Tue 2006-09-12 14:18:05, Jordan Crouse wrote:
> On 12/09/06 14:14 -0400, Jim Gettys wrote:
> > > Alternatively, hack kernel to take control from X without actually
> > > switching consoles. That should be possible even with current
> > > interface.
> > 
> > This would require saving/restoring all graphics state in the kernel
> > (and X already has that state internally).  Feasible, but seems like
> > duplication of effort.  I haven't checked if there are any write-only
> > registers in the Geode (though, thankfully, this kind of brain damage is
> > rarer than it once was).  This then begs interesting kernel/X
> > synchronization issues, of course.
> 
> We don't need any kernel output during suspend or resume.  Thus, if the VT
> doesn't change, then the kernel doesn't need worry about saving or restoring 
> the graphics state, and thats the way it should be, IMHO.
> Whoever owns the current VT should be in charge of saving and restoring 
> the registers.
> 
> So, we would need some way of indicating the "ownership" of the VT.  And
> in reality, we really only to know if the framebuffer console owns it or
> not, so a boolean would suffice.  In the past, I've used KD_TEXT and 
> KD_GRAPHICS for this purpose.  As an example, on the Geode LX, I assume
> that if the vc_mode is KD_GRAPHICS, then we don't own it, and we don't
> do 2D accelerations.  If the mode is KD_TEXT then we are free to use the
> 2D engine.   All I needed to add ws a notifier chain to let the framebuffer
> know when the mode switched, and I was happy.  I'm not sure if thats the
> smartest way to handle it permanently, but it works in a pinch.

KD_TEXT vs. KD_GRAPHICS looks like the way to go. Just tell X you want
console back, but then don't actually redraw/switch consoles. We
probably want that on normal PCs, too... console switch for
suspend-to-RAM looks ugly.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  reply	other threads:[~2006-09-14  9:20 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-08-30 18:40 [RFC][PATCH 1/2] " Pallipadi, Venkatesh
2006-08-30 19:43 ` Matthew Garrett
2006-08-31 23:13   ` Bjorn Helgaas
2006-09-01  0:30     ` [OLPC-devel] " Jim Gettys
2006-09-01  3:53       ` Len Brown
2006-09-01  4:12         ` Matthew Garrett
2006-09-01 15:51           ` Jordan Crouse
2006-09-01 13:14         ` [OLPC-devel] Re: [RFC][PATCH 1/2] " Carl-Daniel Hailfinger
2006-09-01 21:52         ` Andi Kleen
2006-09-01 22:57           ` Alan Cox
2006-09-04 13:13         ` Pavel Machek
2006-09-04 13:09       ` Pavel Machek
2006-09-05 14:31         ` Jim Gettys
2006-09-06 10:37           ` Pavel Machek
2006-09-06 14:58             ` Jordan Crouse
2006-09-12  9:21               ` Pavel Machek
2006-09-12 18:14                 ` Jim Gettys
2006-09-12 18:27                   ` Mitch Bradley
2006-09-12 20:18                   ` Jordan Crouse
2006-09-14  9:20                     ` Pavel Machek [this message]
2006-09-14  9:18                   ` Pavel Machek
2006-09-14 11:29                     ` Jim Gettys
2006-09-06 15:19             ` [OLPC-devel] Re: [RFC][PATCH 1/2] " Jim Gettys
2006-09-12  9:21               ` Pavel Machek

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