From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1Rp256-0005FQ-RL for garchives@archives.gentoo.org; Sun, 22 Jan 2012 18:23:58 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 47B8FE098A; Sun, 22 Jan 2012 18:23:38 +0000 (UTC) Received: from mail-ww0-f53.google.com (mail-ww0-f53.google.com [74.125.82.53]) by pigeon.gentoo.org (Postfix) with ESMTP id DB0BDE098A for ; Sun, 22 Jan 2012 18:22:17 +0000 (UTC) Received: by wgbdr12 with SMTP id dr12so977182wgb.10 for ; Sun, 22 Jan 2012 10:22:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; bh=Xzn0OtnGEi7LUcizgvgQ96dWVbz3uDBfvmY9Eksty0U=; b=odUhMuHWsic5ZaN/Eggs1l8HpSAYvg6cCaCzxu+p4ImtX4j4nntGq7nI3uyueFIXsg hsMjFbMX/dbQGxztoBBr2YvHqs5LdIIHEPYgoreH1GVw2i6ZURDhTrP6+fsICMiKrYai 2D6YuPePVU6Dqdbmzb6twyc2dvTlEMc8wWrGQ= Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Received: by 10.180.19.97 with SMTP id d1mr8643400wie.12.1327256537142; Sun, 22 Jan 2012 10:22:17 -0800 (PST) Received: by 10.223.160.73 with HTTP; Sun, 22 Jan 2012 10:22:17 -0800 (PST) In-Reply-To: <4F1C504D.6010105@gmail.com> References: <4F1C504D.6010105@gmail.com> Date: Sun, 22 Jan 2012 10:22:17 -0800 Message-ID: Subject: Re: [gentoo-user] KVM problems - anyone know _why_ it happens? From: Mark Knecht To: gentoo-user@lists.gentoo.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Archives-Salt: 3b6450c2-47de-4d20-ad9c-55c430586311 X-Archives-Hash: bd8db190c41dcde9111fde7212232c7b On Sun, Jan 22, 2012 at 10:07 AM, G.Wolfe Woodbury wro= te: > 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 fro= m > the monitor. =C2=A0I 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. > > I did as others suggested and tried several until I found one that worked= . > =C2=A0Sometimes a slightly different model/serial/part no KVM from the sa= me > manufacturer would/wouldn't work. > > -- > G.Wolfe Woodbury > redwolfe@gmail.com > > Thanks. Sounds about like what was going on at his place and it's a reasonable evaluation potentially. I guess I could have made it a bit more clear early on - I'm not looking to solve anything here and I'm not buying KVMs. I was just curious as to the root cause of the problem. I've seen it discussed periodically for over a decade but never any strong analysis of why it happens. It's not a huge problem to the community. Cheers, Mark