Re: [gentoo-user] KVM problems - anyone know _why_ it happens?

[Michael Mol]

On Sun, Jan 22, 2012 at 2:30 PM, Mark Knecht <markknecht@×××××.com> wrote:
> On Sun, Jan 22, 2012 at 10:58 AM, Michael Mol <mikemol@×××××.com> wrote:
>> On Sun, Jan 22, 2012 at 1:07 PM, G.Wolfe Woodbury <redwolfe@×××××.com> wrote:
>>> On 01/22/2012 12:42 PM, Mark Knecht wrote:
>>>>
>>>> I played a bit with get-edid | parse-edid. Logically that stuff even
>>>> working says the VGA monitor cable is bidirectional. I started wondering if
>>>> the KVM messes up the data coming back, or what else might be going on.
>>>> Thanks for the ideas, Mark
>>>
>>> Many of the cheap KVM models do, indeed, mess up the EDID data coming from
>>> the monitor.  I suspect that this is from old design specs that have too
>>> much pull-up/pull-down on the EDID lead since the boxen haven been
>>> re-engineered for newer, higher resolution and higher speed monitors.
>>>
>>> I have had problems specifically with the BELKIN KVMs.
>>>
>>> It may also be that the video drivers for Linux are just enough different
>>> (necessarily) from the MSFT drivers to not reliably sense the EDID return
>>> signals.
>>
>> Concur. It sounds like the EDID block isn't making it back or is
>> somehow messed up. x11-misc/read-edid would help in investigating that
>> kind of issue.
>>
>
> Yeah, I did that sort of stuff already. It didn't tell me anything
> specific as best I could tell. However I haven't done it with the KVM
> out. Maybe comparing the two responses would give some clues.
>
> Also, thanks for the pointer to xvidtune. Interesting little app.
> QUESTION: Do you know how to get the data for each monitor/video card
> combo? So far I haven't figured out how to tell it Screen2. Seems to
> only give me Screen0 as best I can tell.
>
> I'm a bit nervous to just start trying things.

If you're not using Xinerama, you can specify screens by changing
$DISPLAY. e.g. :0.0 is screen 0, :0.1 is screen 1, :0.2 is screen 2...

-- 
:wq