Linux 6.5 Bringing Improvements To PS/2 Mouse & Keyboard Handling

[phoronix]

Phoronix: Linux 6.5 Bringing Improvements To PS/2 Mouse & Keyboard Handling

Hopefully by now all of you have moved off PS/2 mice and keyboards, but should you still have some old systems chugging along with PS/2 hardware, there are some improvements to find with the Linux 6.5 kernel currently under development...

https://www.phoronix.com/news/Linux-6.5-PS2-Improvements

[Chrispynut]

Old systems? PS/2 is popular on new systems, particularly with overclockers.

[MorrisS.]

Normally I prefer motherboards provided by PS2 ports. Some motherboards have just one PS2 port but I don't understand if it is a converted USB port.

[schmidtbag]

Old systems? PS/2 is popular on new systems, particularly with overclockers.

Hmm never thought about that but it makes a lot of sense.
They're also popular among competitive gamers. Ostensibly, they have better latency since they have their own interrupt. As far as I understand, that's the reason why mouse pointers in the 90s could still move while the rest of the PC was frozen from something like an infinite loop.
I have strong doubts any of this makes any real difference to gamers though. I have a couple PS/2 keyboards simply because they still work and are easy to adapt to USB with a low cost. Haven't had a PS/2 mouse in maybe 20 years though.

[iavael]

For keyboards PS/2 is superior to USB because of native NKRO, lower latency or cpu usage.

[docontra]

Normally I prefer motherboards provided by PS2 ports. Some motherboards has just one PS2 port but I don't understand if it is a converted USB port.

Judging by the APM/ACPI ("Wake On X")[1] BIOS options on the new-ish (~2017-2022) single-port MoBos I've encountered, it should be the real deal.

Old systems? PS/2 is popular on new systems, particularly with overclockers.

Know/can speculate of any reason why? On the technical level, the big advantage of PS/2 over USB was compatibility during early boot through the very early 2010's (in BIOS/Firmware config screens, but in my experience especially under bootloaders), but that has long stopped being an issue[2]. I can believe that also translates to "compatibility under broken CPU/RAM overclock", but by that point surely you'd clear CMOS and begin anew . The non-technical advantage still remains being harder to, ahem, repurpose, since you "need" to shut down the repurposee system and the repurposed must have a system with PS/2 (which must be shut down and rebooted) or the USB adapter

[1]: Wake on Keyboard (and sometimes even Wake on Mouse) typically requires a PS/2 keyboard(/mouse) connected to the respective PS/2 port.
[2]: About the time EFI started rolling out, but I've used several BIOS only systems that have no issue with USB inputs on early boot. In modern systems you can still get SOL by looking too hard at the "Enable Legacy USB support" option, but I've rolled out multiple systems with that setting disabled and had no issues in Firmware/early boot.

[iavael]

Know/can speculate of any reason why?

Because USB requires host to poll input devices while in PS/2 device sends interrupts to host. For low polling rate you get higher input lag for USB compared to PS/2 and for high polling rate (like 1000 HZ) you get higher CPU usage.
If you have 1000 Hz gaming mouse you can try to watch you CPU consumption while constantly moving mouse. It may become really high on some systems.

[MorrisS.]

PS/2 is still better than USB ports for input devices due to the specific nature of PS/2 technology against USB. As for me, PS/2 is a modern solution. Producers prefer to provide motherboards devoid of PS/2 to get benefits from standardization. Likely, PS/2 is the only past feature which stays modern in the current day.

https://pcguide101.com/motherboard/5-reasons-why-do-motherboards-still-have-ps2-port/

https://computerinfobits.com/why-do-motherboards-still-have-ps2/

Sometime, an issue happens during my PS/2 mouse action which deals with the cursor freezes on the page just after clicking on it and the page moves with the cursor until I click again the button of the mouse in order to fix the freeze. I don't know if these improvements are to fix this kind of issue.

[bezirg]

I still use PS/2 . I specifically dnt buy motherboards that don't provide any PS/2 ports

[RejectModernity]

I have a ps2 keyboard, interrupts are simply superior to polling for input devices.