How do I debug PS/2 Keyboard Problems in Fedora 20?

asked 2014-04-14 03:50:33 -0500

updated 2014-04-14 04:48:38 -0500

mether gravatar image

I've reconditioned a keyboard that has an old AT connector and it's connected to my computer through an AT->PS/2 converter.

I've verified that the keyboard works. With my regular USB keyboard plugged-in, I plugged in the PS/2 keyboard and could type perfectly.

When I boot the computer with only the PS/2 keyboard plugged-in:

  • I can use the keyboard for pre-boot bios configuration
  • I can use the keyboard in grub2
  • I can not use the keyboard at all

I have not looked at the logs with only the PS/2 keyboard plugged-in. However, with both keyboards plugged-in:

 $ dmesg -t |grep i8042
 i8042: PNP: PS/2 Controller [PNP0303:PS2K] at 0x60,0x64 irq 1
 i8042: PNP: PS/2 appears to have AUX port disabled, if this is incorrect please boot with i8042.nopnp
 serio: i8042 KBD port at 0x60,0x64 irq 1
 input: AT Translated Set 2 keyboard as /devices/platform/i8042/serio0/input/input2

That mention of AUX port is fine, because I don't have use a PS/2 mouse.

I'm not sure how to proceed from here. Could it be an issue with my xorg.conf? How should I debug?

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It's a basic idea, but have you tried unpluggin/replugging the PS/2 keyboard after booting?

Ahmad Samir gravatar imageAhmad Samir ( 2014-04-14 03:59:57 -0500 )edit

Before you try the above, please be aware that PS/2 keyboards are not hot pluggable. I've blown motherboards by plugging in to running systems. I always used to power off completely when dicking around with PS/2 - it's one of the reasons why USB is so cool.

You may want to look at the power available to your system - PS/2 will be on of the first to go if there's not enough oomph from your power supply.

cobra gravatar imagecobra ( 2014-04-14 05:16:00 -0500 )edit

That's news to me, I never had that happen on the two boxes - back in the day - when I used PS/2 ports; searching online suggests that damage can sometimes happen if you unplug or plug a PS/2 device while the machine is powered on (sorry about that I didn't know).

My idea was that a kernel module is not loaded at boot for the PS/2 keyboard; I think a safer way to test is booting with the "rescue" entry in grub, this one is built without the HostOnly dracut option, so all the default modules are available at/after boot.

Ahmad Samir gravatar imageAhmad Samir ( 2014-04-14 05:48:13 -0500 )edit

This is an AT keyboard with a ps/2 adapter that draws some decent current, but the motherboard is made in the last 4 years so I expect the power pins to have a decent protection circuit. I have a feeling it has something to do with PS/2 becoming modular in the kernel with 3.13 as noted by

zagra gravatar imagezagra ( 2014-04-14 13:18:57 -0500 )edit

I'll try testing the hotplug later tonight when I can be around that specific workstation.

zagra gravatar imagezagra ( 2014-04-14 13:20:17 -0500 )edit