On 15 November 2015 at 09:18, bian <b...@vivaldi.net> wrote: > On 2015-11-14 17:22, Mike Burns wrote: > > I believe Xorg -configure has been useless for a long time. >> With a hardware that just works, X just works. If a xorg.conf is needed >> (as when e.g. using vesa instead of a misbehaving driver), >> it is easier to write a simple one from xorg.conf(5) by hand. >> >> Jan >> > > This is one way of looking at it, yes. However, the quality of the > produced xorg.conf.new is fine. >
I realise these are relatively rare cases for maybe somewhat exotic needs, but there are legitimate reasons why you might want to use Xorg -configure. tl;dr: Just because you can autodetect once (i.e. "X just works") doesn't mean you can autodetect every time. Suppose your video output is connected using a VGA connector (not necessarily one still on your graphics card, maybe just in the form of a DVI to VGA adapter somewhere along the line), and suppose your VGA cabling does not connect the I²C <https://en.wikipedia.org/wiki/I%C2%B2C> / DDC < https://en.wikipedia.org/wiki/Display_Data_Channel> pins. Why might those pins not be connected? First, not all 15-pin VGA cables are equal (and there even were very early cables with a DE-9M on at least one end instead of DE-15M D-subs on both ends, cf. <http://www.allpinouts.org/index.php/VGA_9_to_15_pin>). Second, someone might be using this kind of a balun < http://www.dx.com/p/utp8201ar-300-single-channel-twisted-pair-vga-video-balun -receiver-black-184382> or any number of similar devices, which only connect 8 pins, because the VGA signal is carried (balanced, but still carried) over existing Cat 5/6/whatever twisted pair with 8P8C/RJ45 connectors (count the shielding if fully connected and you might say that's 9 pins). Without the Display Data Channel, monitor/resolution/etc. autodetection will not work. You might still wish to rely on autodetection for initial setup, when you would have a compatible monitor directly connected WITH DDC. Xorg -configure would write you a nice xorg.conf. Afterwards, in regular use, your monitor would be connected WITHOUT DDC, preventing any sensing/plug and play/autodetection from working. Don't assume that just because you can do X once, you'll always be able to do X ('scuse the pun). regards, âropers
