linux-kernel - Re: 2.6.29-rc powerpc G5 Xorg legacy

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Date:	Thu, 22 Jan 2009 16:16:10 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Hugh Dickins <hugh@...itas.com>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	"Rafael J. Wysocki" <rjw@...l.pl>, linuxppc-dev@...abs.org,
	linux-kernel@...r.kernel.org
Subject: Re: 2.6.29-rc powerpc G5 Xorg legacy_mem regression


> That's as far as I took it: I can see there's code to set up
> "Legacy VGA memory" but it looks like that's not coming into play.
> dmesg and .config attached: I think you'll get to the point much
> quicker than I would.
> 
> Though I bet you're busy at the moment: no hurry, I can comment
> out the pci_create_legacy_files() from drivers/pci/bus.c for now.

It's actually an X bug :-(

IE, I always create the legacy files, I just make mmap fail when legacy
VGA isn't available. This is the right way to do it, as it properly
informs X that yes, I do support the new API and no, there's no point in
trying to access legacy VGA memory on this machine.

I honestly don't see how I can fix that without making proper support
for legacy memory / IO impossible, and thus guaranteeing that X will
eternally continue to crap on random bits of /dev/mem in the future :-(

Cheers,
Ben.


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