linux-kernel - Re: [PATCH 5/5] drm/i915: Kick out vga console

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Date:	Mon, 30 Jun 2014 10:19:41 +0200
From:	David Herrmann <dh.herrmann@...il.com>
To:	Chris Wilson <chris@...is-wilson.co.uk>, Ed Tomlinson <edt@....ca>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
	DRI Development <dri-devel@...ts.freedesktop.org>,
	LKML <linux-kernel@...r.kernel.org>,
	David Herrmann <dh.herrmann@...il.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Dave Airlie <airlied@...ux.ie>
Subject: Re: [PATCH 5/5] drm/i915: Kick out vga console

Hi

On Mon, Jun 30, 2014 at 8:59 AM, Chris Wilson <chris@...is-wilson.co.uk> wrote:
> On Sat, Jun 28, 2014 at 11:55:19PM -0400, Ed Tomlinson wrote:
>> On Saturday 28 June 2014 15:28:22 Ed Tomlinson wrote:
>>
>> Resend without html krud which causes list to bounce the message.
>>
>> > Hi
>> >
>> > This commit ( a4de05268e674e8ed31df6348269e22d6c6a1803 ) hangs my boot with 3.16-git.  Reverting it lets the boot proceed.
>> >
>> > I have an i7 with a built-in i915 and an pcie r7 260x.  The R7 is the primary console.  The i915 is initialized
>> > but does not have a physical display attached.
>> >
>> > With the patch applied the boot stops at the messages:
>> >
>> > [drm] Memory usable by graphics device = 2048M
>> > [drm] Replacing VGA console driver
>
> The issue looks like that we are ripping out the radeon fb_con whilst it
> is active and that upsets everyone. In which case, I think the
> compromise is:

do_take_over_console() should only touch console-drivers like fbcon.
How does this affect the underlying fbdev device? Ripping out active
or inactive fbcon should be just fine, shouldn't it?

Given that this hard-locks at kick_out_vgacon(), this looks more like
a dead-lock to me.

Thanks
David
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