VESA modes

[Net Llama!]

On Mon, 19 Mar 2007, Jorge Almeida wrote:
> On Mon, 19 Mar 2007, Net Llama! wrote:
>
>> On Mon, 19 Mar 2007, Jorge Almeida wrote:
>>> I could use some help to understand what VESA standard modes are, and
>>> how to use such beasts. From what [I think] I understood, the xorg server has
>>> built-in knowledge about VESA modes. Hence, instead of writing a line like
>>> ModeLine "1280x1024" 108.0   1280 1328 1440 1688 1024 1025 1028 1066 +hsync +vsync
>>> in Section "Monitor" of xorg.conf, and then writing
>>> Modes "1280x1024"
>>> in Section "Screen", SubSection "Display",
>>> one could simply write the latter, because the above modeline happens to
>>> be one of the VESA modes.
>>> What confuses me no-end is that the label "1280x1024" is associated with
>>> several modelines, corresponding to different refresh rates. So, how
>>> does the server know what to do? In KDE, one can choose a frequency in
>>> the Control Panel, but that must be a front-end to something more
>>> basic...
>>
>> X has its own built in modes, which are separate and unrelated to VESA
>> modes.  The X driver that you're using will determine which modes get
> This is what I meant (from the xorg.conf man page):
> 	The  Identifier entry specifies the unique name for this monitor.  The Monitor section provides information about the specifications
> 	of the monitor, monitor-specific Options, and information about the video modes to use with the monitor.  Specifying video modes  is
> 	optional because the server now has a built-in list of VESA standard modes.  When modes are specified explicitly in the Monitor sec-
> 	tion (with the Modes, ModeLine, or UseModes keywords), built-in modes with the same names are not  included.   Built-in  modes  with
> 	different names are, however, still implicitly included.
>
>> validated, and how they are named.  Generally speaking, starting X with
>> the following command:
>> startx -- -logverbose 6
>>
>> will show you alot more information about the mode validation process.
>> The X driver that you use will determine whihc information appears.
>>
> OK, this is just a piece of that information:
> 	(II) NVIDIA(0):   Validating Mode "1280x1024":
> 	(II) NVIDIA(0):     1280 x 1024 @ 60 Hz
> 	(II) NVIDIA(0):     Mode Source: VESA
> 	(II) NVIDIA(0):       Pixel Clock      : 108.00 MHz
> 	(II) NVIDIA(0):       HRes, HSyncStart : 1280, 1328
> 	(II) NVIDIA(0):       HSyncEnd, HTotal : 1440, 1688
> 	(II) NVIDIA(0):       VRes, VSyncStart : 1024, 1025
> 	(II) NVIDIA(0):       VSyncEnd, VTotal : 1028, 1066
> 	(II) NVIDIA(0):       H/V Polarity     : +/+
> 	(II) NVIDIA(0):     Mode is valid.
> 	(II) NVIDIA(0):
> 	(II) NVIDIA(0):   Validating Mode "1280x1024":
> 	(II) NVIDIA(0):     1280 x 1024 @ 75 Hz
> 	(II) NVIDIA(0):     Mode Source: VESA
> 	(II) NVIDIA(0):       Pixel Clock      : 135.00 MHz
> 	(II) NVIDIA(0):       HRes, HSyncStart : 1280, 1296
> 	(II) NVIDIA(0):       HSyncEnd, HTotal : 1440, 1688
> 	(II) NVIDIA(0):       VRes, VSyncStart : 1024, 1025
> 	(II) NVIDIA(0):       VSyncEnd, VTotal : 1028, 1066
> 	(II) NVIDIA(0):       H/V Polarity     : +/+
> 	(II) NVIDIA(0):     Mode is valid.
>
> There are other "1280x1024" that were not validated, which agrees with
> the monitor documentation. However, the two modes above have the same
> label "1280x1024". Near the end of the log file, there is the line:
> 	(II) NVIDIA(0): Setting mode "1280x1024"
> Now, what mode is this? (What refresh rate will be used? The KDE control
> center offers the two choices 75Hz and 60 Hz. What would be the
> lower-level way to choose?)

That information appears further down in your X log, specifically where 
the mode pool is listed.  Generally speaking for the nvidia X driver, 
1280x1024_60 gets you 1280x1024 at 60, and 1280x1024_75 gets you 
1280x1024 at 75.


-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Lonni J Friedman                        netllama at linux-sxs.org
LlamaLand				http://netllama.linux-sxs.org