Xorg -configure questions

[Alan Coopersmith]

On 02/24/11 11:00 AM, gene heskett wrote:
> On Thursday, February 24, 2011 01:53:16 pm Alan Coopersmith did opine:
> 
>> On 02/24/11 07:06 AM, lfs lfs wrote:
>>>     From: lfs lfs <linuxfromscratch at yahoo.com>
>>>     Subject: Xorg -configure questions
>>>     To: xorg at lists.freedesktop.org
>>>     Date: Thursday, February 24, 2011, 8:04 AM
>>>     
>>>     Hi,
>>>     
>>>       for example:
>>>     ----------------------------------------------------------
>>>     Xorg -configure  //1st flickering here
>>>     cp -rf /root/xorg.conf.new /etc/X11/xorg.conf
>>>     startx //2nd flickering here
>>>     ----------------------------------------------------------
>>>     
>>>     This will flicker screen twice. How can I make this flicker only
>>>     once?
>>
>> Drop the first two steps and startx with no xorg.conf.
>>
>> There's no point creating one if you're not going to change any settings
>> from the defaults, just let the server run with the defaults from its
>> autoconfiguration.
> 
> This is not always the magic twanger, Alan.  With no xorg.conf, it insists 
> on using the ati drivers if they are installed, for an ati card.  Or the nv 
> drivers for an nvidia card.  This is deadly to the performance of an rtai 
> based application such as emc.  So we must make enough of an xorg.conf to 
> specify the vesa driver, which has no or very little effect on rtai 
> latencies and gives us more than adequate video to carve whatever we can 
> write gcode to do.  Admittedly, this is a 'narrow' application, but it 
> should be considered.

That falls under "changing the settings from the defaults" - if you read
what I said "if you're not going to change any settings from the defaults"
you'll see no conflicts between my advice and your requirements.

Though if you want the vesa driver, the above instructions are also the
wrong way to do it - you wouldn't run Xorg -configure, you'd just run

cat > /etc/X11/xorg.conf << _EOF
Section "Device"
        Identifier  "Card0"
        Driver      "vesa"
EndSection
_EOF

Though I just ship a /usr/lib/X11/xorg.conf.vesa in my xorg packages so
that you don't even need to that, just "Xorg :0 -config xorg.conf.vesa",
but not all packagers do so.

-- 
	-Alan Coopersmith-        alan.coopersmith at oracle.com
	 Oracle Solaris Platform Engineering: X Window System