vesa driver reports many modes, but only allows a few

[Ross Boylan]

On Mon, 2010-03-01 at 14:40 -0500, Adam Jackson wrote:
> On Sun, 2010-02-28 at 23:28 -0800, Ross Boylan wrote:
> > Could anyone explain to me what the attached log means?
> > 
> > X 7.5 detects a rich array of BIOS modes, but then runs through a list
> > of modes and says "no mode of this name".  Should it be using something
> > like "104" or  "104 (1024x768)" instead of, e.g., "1024x768"?  Then X
> > tries a less strict probe, and rejects all but a couple of
> > low-resolution modes with "hsync out of range".  I have no xorg.conf
> > file.
> 
> The vesa driver attempts to find the intersection of the list of modes
> in the BIOS with the list of modes from EDID.  You don't have an EDID,
> so this (unsurprisingly) gives you no modes.
> 
> If we get to this point, we attempt to validate the BIOS mode list
> against the sync ranges configured for the monitor in xorg.conf, or from
> the defaults if there's no explicit configuration.  That's what the
> "trying less strict filter" bit means.  The default sync ranges for your
> server appear to be just big enough for 800x600.
> 
> If you want bigger modes, configure a bigger sync range:
> 
> # big enough for 1600x1200 @ 60Hz
> Section "Monitor"
>     Identifier "Monitor0"
>     HorizSync 31.5 - 75.0
>     VertRefresh 56.0 - 61.0
> EndSection
I tried an xorg.conf that had *only* the previous Monitor section.  It
didn't seem to get hooked up to anything else.  I also tried giving it
an identifier of "<default monitor>" since the log indicated that was
the monitor being used.  In either case, I got 

(==) Using config file: "/etc/X11/xorg.conf"
(==) No Layout section.  Using the first Screen section.
(==) No screen section available. Using defaults.
(**) |-->Screen "Default Screen Section" (0)
(**) |   |-->Monitor "<default monitor>"
(==) No monitor specified for screen "Default Screen Section".
        Using a default monitor configuration.

Do I need to create a complete xorg.conf?

Ross
> 
> Use the gtf(1) utility to calculate the upper bounds for sync ranges for
> the resolution you want:
> 
> % gtf 1600 1200 60
> 
>   # 1600x1200 @ 60.00 Hz (GTF) hsync: 74.52 kHz; pclk: 160.96 MHz
>   Modeline "1600x1200_60.00"  160.96  1600 1704 1880 2160  1200 1201 1204 1242  -HSync +Vsync
> 
> - ajax
> _______________________________________________
> xorg mailing list
> xorg at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/xorg