war story: keyboard failure leads to sustained mayhem
This story could be told in order of discovery. That would be more fun. But I'm going to explain it as plainly as possible to make it more useful. I have a KVM switch (Keyboard Video Mouse) that lets four computers share one keyboard, display, and mouse. Unbeknownst to me, the keyboard started generating a rapid stream of ESC [ D (back arrow) sequences. I'm not sure whether it is all the time or just some of the time. The next time I booted one of the computers, it seemed to fail to find its hard drives. It was more than a decade old, so rather than fixing it, I replaced it. I now think that a continuous stream of backarrow keys confused the BIOS (or the RAID card BIOS) when the machine was booting. But at that time, it seemed to be a simple case of old hardware wearing out. Another computer had different symptoms, but again showed disk problems. When I did disk diagnostics, I was puzzled by the results: no problem. Eventually, I found the keyboard problem and have thrown the keyboard away. I have no idea how long it had been misbehaving. Lessons re-learned: - symptoms don't always point clearly to the disease. - conclusions should remain provisional - it's amazing how long you can overlook a stuck keyboard key - apparently I really only use the KVM for booting; it would be nice if PCs had been designed to be happy headless
On 15-07-05 10:59 PM, D. Hugh Redelmeier wrote:
- apparently I really only use the KVM for booting; it would be nice if PCs had been designed to be happy headless
In older days (a few generations of PC ago) there used to be a BIOS setting where you could tell it to ignore keyboard errors. You would enable that feature if you wanted to run the computer without a keyboard. I haven't looked to see if such a feature still exists in modern day BIOS but I don't see why they would have removed the option unless it will ignore keyboard errors automatically. -- Cheers! Kevin. http://www.ve3syb.ca/ |"Nerds make the shiny things that distract Owner of Elecraft K2 #2172 | the mouth-breathers, and that's why we're | powerful!" #include <disclaimer/favourite> | --Chris Hardwick
On 07/06/2015 09:10 AM, Kevin Cozens wrote:
On 15-07-05 10:59 PM, D. Hugh Redelmeier wrote:
- apparently I really only use the KVM for booting; it would be nice if PCs had been designed to be happy headless
In older days (a few generations of PC ago) there used to be a BIOS setting where you could tell it to ignore keyboard errors. You would enable that feature if you wanted to run the computer without a keyboard. I haven't looked to see if such a feature still exists in modern day BIOS but I don't see why they would have removed the option unless it will ignore keyboard errors automatically.
I have 4 computers here, one with a year old motherboard. 3 of them can run headless and the other, an old Compaq, I just leave an old keyboard plugged in, but still access it via KVM. Like I said, check the settings.
| From: James Knott <james.knott@rogers.com> | On 07/06/2015 09:10 AM, Kevin Cozens wrote: | > On 15-07-05 10:59 PM, D. Hugh Redelmeier wrote: | >> - apparently I really only use the KVM for booting; it would be | >> nice if PCs had been designed to be happy headless | > | > In older days (a few generations of PC ago) there used to be a BIOS | > setting where you could tell it to ignore keyboard errors. | I have 4 computers here, one with a year old motherboard. 3 of them can | run headless and the other, an old Compaq, I just leave an old keyboard | plugged in, but still access it via KVM. Before I got a PC, I had Sun workstations. They were willing to talk via a serial port to a "console" (they could use a display and keyboard too). This let you do things like reboot when hung, watch all the exciting messages during booting, configure the machine, run hardware diagnostics, etc. I don't really want to lose those functions. On PCs, they seem to require a console (or some quite expensive "management" features). That's why I use a KVM (and grumble). I think that the expensive management functions use ethernet transport. For security, it ought to be separate from other networks. I have no experience with them. Unfortuately, I think that the protocols are proprietary and different for each brand of computer. KVMs are either expensive or deficient. Or both. - cheap ones only support VGA, a very obsolete standard - some cheap KVMs don't pass DDC info so the OS cannot determine characteristics of the monitor. This causes a variety of problems (some modern Linux distros won't work out of the box with this). - some better cheap KVMs pass DDC information, but only to the computer currently selected. This works badly after a power failure when each computer is rebooting at the same time. - there are issues (that I don't understand) about keyboard and mouse states carrying over on switching. - I have another KVM that is normally sold for ~$500 that does a lot right: support dual-link DVI, does pass DDC to all computers. I paid $100, so that was a great choice. Even so, it gets a bit confused by some mice. HDMI switches are quite cheap these days. That would handle the V part of KVM. Maybe the clutter of multiple keyboards and mice would be OK. HDMI includes an ethernet signal now. Someone should build a pair of dongles to ship K and M stuff over that channel. USB over ethernet is probably already a thing.
On 07/06/2015 10:37 AM, D. Hugh Redelmeier wrote:
HDMI switches are quite cheap these days. That would handle the V part of KVM. Maybe the clutter of multiple keyboards and mice would be OK. HDMI includes an ethernet signal now. Someone should build a pair of dongles to ship K and M stuff over that channel. USB over ethernet is probably already a thing.
I have a KVM that does HDMI and USB, so video, keyboard, mouse and even audio are switched. As I said, the one computer requires a keyboard plugged in, but all work through the KVM.
| From: James Knott <james.knott@rogers.com> | I have a KVM that does HDMI and USB, so video, keyboard, mouse and even | audio are switched. Nice! What is the brand and model of the KVM? | As I said, the one computer requires a keyboard | plugged in, but all work through the KVM. USB doesn't count as a keyboard? Or is it that the switch doesn't "fake" the keyboard and mouse for the unselected computers? In that case, it would look to the computer as if the mouse and keyboard were plugged in each time the computer were selected and unplugged each time it is deselected. I have a USB KVM switch that switches auxiliary USB but for USB keyboard and mouse sockets fakes them for the unselected computers.
On 07/06/2015 11:36 AM, D. Hugh Redelmeier wrote:
USB doesn't count as a keyboard? Or is it that the switch doesn't "fake" the keyboard and mouse for the unselected computers? In that case, it would look to the computer as if the mouse and keyboard were plugged in each time the computer were selected and unplugged each time it is deselected.
It appears the KVM doesn't "fake" a keyboard, so I have to plug a real keyboard into that one computer. All the rest work fine as is, after configuring the CMOS so that the computer will boot without a keyboard. I haven't noticed any issues with not having a mouse plugged in, but then a mouse isn't usually critical for using a computer. Back in the days before GUIs, we usually didn't even own a mouse.
| From: James Knott <james.knott@rogers.com> James says that his KVM is <http://www.newegg.ca/Product/Product.aspx?Item=N82E16817145111&cm_re=kvm-4uhm-_-17-145-111-_-Product> (not currently in stock) | It appears the KVM doesn't "fake" a keyboard, so I have to plug a real | keyboard into that one computer. All the rest work fine as is, after | configuring the CMOS so that the computer will boot without a keyboard. That makes sense | I haven't noticed any issues with not having a mouse plugged in, but | then a mouse isn't usually critical for using a computer. Back in the | days before GUIs, we usually didn't even own a mouse. That too makes sense. If you read the critical reviews on newegg, it looks as if the monitor doesn't make EDID information about the monitor work for unselected computers. This can cause problems. Perhaps not for old fashioned text consoles (like BIOS setup screens). ============= I went googling for interesting KVMs and came up with this: <http://www.amazon.com/Displayport-Switch-Control-Desktop-Product/dp/B00V5I0QLE> Amazon describes it as a 12-port DisplayPort KVM! Unfortunately, the manufacturer says you can connect two PC to it, no more. I got tired of hunting for unicorns. Not only are KVMs that match my requirements rare and expensive, it is hard to identify them amongst the descriptions of inferior products. Here's a useful document from Microsoft: <http://download.microsoft.com/download/7/E/7/7E7662CF-CBEA-470B-A97E-CE7CE0D98DC2/KVM-Win7.docx> It deals only with video issues. Apparently there is/was a "Windows Logo Program" for KVM switches. I don't remember ever seeing a Windows logo on a KVM, but I would take it as a Good Thing. Oh, it seems that the logo program was retired "with the release of the Windows Logo Kit (WLK) for Windows Server 2008 RTM." Darn.
On 07/07/2015 01:03 AM, D. Hugh Redelmeier wrote:
If you read the critical reviews on newegg, it looks as if the monitor doesn't make EDID information about the monitor work for unselected computers. This can cause problems. Perhaps not for old fashioned text consoles (like BIOS setup screens).
I haven't noticed any problems.
| From: D. Hugh Redelmeier <hugh@mimosa.com> | - I have another KVM that is normally sold for ~$500 that does a lot | right: support dual-link DVI, does pass DDC to all computers. I | paid $100, so that was a great choice. Even so, it gets a bit | confused by some mice. This KVM is an IOGEAR GCS1784. <http://www.newegg.ca/Product/Product.aspx?Item=N82E16817399043CVF> Some of the reviewers on the newegg site mention keyboard and mouse problems. The KVM emulates the keyboard and mouse for each of the computers so switching will be seamless. This means that the real mouse and keyboard have to be pretty generic or bad things happen. I could not get any of my wireless-keyboard-and-mouse sets to work. In each case, the mouse could not move down but only up. Sometimes at a disproportionate rate. I could not get a wired keyboard and wireless mouse to work. So now I have a wired keyboard and mouse. Apparently I could have gotten them to work (without the benefit of emulation) by plugging them into the auxiliary USB connector of the KVM. It is switched, but each computer sees the device as being plugged and unplugged whenever the switch switches away or towards the computer. Here are the weasel words that IOGEAR uses to explain this problem: <http://iogear.custhelp.com/app/answers/detail/a_id/1071/related/1>
participants (3)
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D. Hugh Redelmeier -
James Knott -
Kevin Cozens