Gentoo Archives: gentoo-user

From: Michael Mol <mikemol@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] KVM problems - anyone know _why_ it happens?
Date: Sun, 22 Jan 2012 16:07:32
Message-Id: CA+czFiDcm=3TGgkyGW_O=ny=KGJxgO-ZdxnP-WL9XH8rc6EAuA@mail.gmail.com
In Reply to: [gentoo-user] KVM problems - anyone know _why_ it happens? by Mark Knecht
1 On Sun, Jan 22, 2012 at 10:54 AM, Mark Knecht <markknecht@×××××.com> wrote:
2 > I've seen reports for years about folks having problems with some KVMs
3 > under Linux. I've never personally had one myself. However I've been
4 > helping a Windows friend break his Redmond addiction over the last few
5 > months using Gentoo. He has a nice 3 monitor KDE-based system that's
6 > been working fine but there was one monitor that refused to set up
7 > with the right resolution. We left it alone for a long time as it was
8 > usable but finally yesterday got together to figure out what was
9 > happening. From the title it should be clear that the problem was a
10 > KVM hooked to that one monitor. Removing the KVM completely solved the
11 > problem.
12 >
13 > Now, what I'm wondering is why this same video card/KVM/monitor
14 > combination which apparently worked in Windows should have any
15 > problems in Linux? Anyone know why?
16 >
17 > In the spirit of full discloser I don't really know that this
18 > _specific_ video card was tested in Windows, but he owns multiple
19 > NVidia 8400GS cards and it's my understanding that other 8400GS cards
20 > did work with this KVM & monitor, so unless it's this specific card
21 > having a defect, or even being just a bit weak in some way, it would
22 > seem to be the insertion of the KVM itself that upset things.
23 >
24 > Looking at the monitor's specs/requirements for running the higher
25 > resolutions it uses, as should not be a surprise, higher frequencies
26 > to do higher resolutions. If the KVM was filtering those a bit then
27 > it's possible things wouldn't work, but that doesn't explain why it
28 > did work in Windows.
29 >
30 > Basically, I looked around in Google for anyone that had real info
31 > about why this problem occurs, couldn't find any that made sense, and
32 > am wondering how to choose a KVM that's going to work out of the box
33 > short of asking for model numbers, etc.
34
35 I assume these are VGA displays?
36
37 I've noticed that the CRTs attached to my Win7 box at work don't get
38 configured for the highest refresh rate unless I force it. Also, I've
39 noticed it decide that '1280x1024' is the 'recommended' resolution for
40 my displays, though they'll do 1600x1200@60Hz.
41
42 It could just be a matter of Windows using 75Hz instead of 85Hz, or
43 60Hz instead of 75Hz.
44
45
46 --
47 :wq

Replies

Subject Author
Re: [gentoo-user] KVM problems - anyone know _why_ it happens? Mark Knecht <markknecht@×××××.com>