xrandr: how to tell it that a screen size is supported?

[J]

On Mon, Jun 7, 2010 at 15:32, Dotan Cohen <dotancohen at gmail.com> wrote:
> On 7 June 2010 16:33, J <dreadpiratejeff at gmail.com> wrote:
>> On Mon, Jun 7, 2010 at 09:04, Dotan Cohen <dotancohen at gmail.com> wrote:

>> A: this is because of your KVM.  When you boot the machine without the
>> KVM pointing to the machine, X has no monitor to probe, so it defaults
>> to a lower safe setting.  When your KVM IS pointed to the system in
>> question, X get's supported modes from the monitor via a DDC probe and
>> thus, you get full resolution.
>>
>
> I know that! Now, how can I add 1680x1050 as a safe setting?

No need to get snippy ;-) Sorry, I have no way of knowing what you do
and don't know so instead of guessing, I erred on the side of
caution... nothing personal, I just can't read minds these days

>> The obvious answer to this one is to only boot when the monitor is
>> connected to the system (e.g. when you have that system switched on
>> the KVM).
>>
>
> If that were always possible, I would not have posted here!

Again, no need to get snippy.  I just said it was the obvious answer,
not the only answer.

>> However, this is from the man page for xrandr (you should read the man
>> page, there's a bit of explanation for each xrandr option in there):
>>
>
> Thanks. Actually, I had read the fine manual sometime in the past few
> months, I should have gone over it again. Sorry!

No worries... Honestly, I didn't know there was an example at the end
until today.  I usually just look at a command synopsis and options...
Heck, I learned something new myself today! :-)

> Lets see, if I get this from -q --verbose:
>
>  1680x1050 (0x4d)  146.2MHz -HSync +VSync *current +preferred
>        h: width  1680 start 1784 end 1960 total 2240 skew    0 clock
>  65.3KHz
>        v: height 1050 start 1053 end 1059 total 1089           clock
>  60.0Hz
>
> Then would you agree that this would be the preferred config:
>
> $ sudo xrandr --newmode "1680x1050" 60.0 1680 1784 1960 2240 1050 1053
> 1059 1089 -hsync +vsync

I'd say that that looks right to me, but YMMV.  That's probably what I'd try...

But read that page NoOp linked to... look at the cvt utility...

Using your resolution:
bladernr at klaatu:/var/log$ cvt 1680 1050
# 1680x1050 59.95 Hz (CVT 1.76MA) hsync: 65.29 kHz; pclk: 146.25 MHz
Modeline "1680x1050_60.00"  146.25  1680 1784 1960 2240  1050 1053
1059 1089 -hsync +vsync

Keep in mind, that's from my laptop, so it may be slightly different
on yours (especially the frequency)

But that page is pretty good reading.  I learned something else today :-)
That page also explains several ways to persistently set that mode so
hopefully one of those will match your system and you'll be golden.

Cheers
Jeff