Intresting X Question...

Ted Mittelstaedt tedm at
Thu Nov 17 12:30:27 GMT 2005

>-----Original Message-----
>From: owner-freebsd-questions at
>[mailto:owner-freebsd-questions at]On Behalf Of Malcolm Kay
>Sent: Tuesday, November 15, 2005 11:15 PM
>To: freebsd-questions at
>Subject: Re: Intresting X Question...
>On Wed, 16 Nov 2005 03:31 pm, Eric Murphy wrote:
>> Maybe some body can explain this alittle better then my google
>> searchs and other readings.
>> My question is this: Lets say your installing BSD on some
>> workstation, you dont know the hardware specs of the monitor
>> (Vertical and Horizontal rates ect..) and you need to
>> configure Xorg. Its my understanding that Xorg runs getconfig,
>> which determines the video card type and monitor type. Once it
>> has that information it applys the information gatherd to the
>> xorg config. Is that how it works? I was going to say, it cant
>> just test a bunch of differnt monitor rates that could cause
>> damage to the monitor.
>Most modern monitors respond to Xorg's enquiry over an I2C bus
>as to its capabilities.
>If this doesn't work then maybe:
>* The monitor is too old.
>* The monitor doesn't subscribe to the 'standards'.
>* Somehow the I2C bus is not working.
>* The monitor manufacturer was overly optermistic when setting
>up the information base for reporting over I2C

You forgot that the video card and Xserver has to support

Yes, Xorg/XFree86 configuration is a breeze when the X server
is able to probe the monitor for the refresh rates.

But there's a lot of cards/server combos that this will not
work with.  And when that happens X configuration is a bitch.

What you have to do is trial and error it.

For example take the onboard video card on the early Compaq
deskpro, it's an S3 based thing.

Under the svga server the monitor is properly probed but
the driver programs the card wrong and you get problems with
the mouse.

Under the s3 server the monitor isn't probed but the mouse
cursor works.

A quick and dirty hack is to boot with the svga server, record
the refresh rates from the X log, then reconfigure for the
usable server and hard code in the refresh rates learned from
the log.  Quick and dirty but effective.  It's also not something
that an inexperienced person would think of.

The other problem is the GUI-based config tool won't of course
work if the card/monitor combo is too weird.  Another solution
to that is running the original script configuration tool.

There are a lot of X config tricks that aren't mentioned in the
Handbook.  If the OP had bothered to list what he was working
with I might even suggest a few that would help.


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