Messages in this thread | | | Subject | Re: uniform input device packets? | Date | Fri, 26 Jun 1998 16:53:08 +0800 | From | David Luyer <> |
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Dossy wrote:
> On 1998.06.24, Pavel Machek <pavel@elf.ucw.cz> wrote: > > Hmm, I do not like this one. What is wrong with attaching 9 mice to my > > PC? > > You currently can't attach 9 mice to a standard PC, so what's the > problem? At least my proposed methodology would *possibly* support > 8. With USB, 9 mice on your USB might be *possible*, but highly > unlikely.
What about a box with a Stallion card and mice plugged into it, to provide all the mice for a many-headed X server (eg, one with 2 or more PCI busses almost fully populated with both PCI and ISA video cards) or for an X server farm using the gpm named pipe and some network sockets to share the mouse over the network?
If you don't think the idea of a 9-headed X server with a Stallion card providing the mouse ports is possible due to CPU limits, just think about a 4 x Pentium II 400 on a dual-PCI bus board (plus ISA). I expect it would work acceptably; I used to run X on my 386 and on machines of non-Intel architecture with much less CPU power.
Or joysticks - even my Playstation has games which support more than 8 players (controller sharing + multitaps to do it, though, but the point is it's possible and people even write software which does it). Someone might have a big-screen display and want a game with a dozen or so gamepads at a shopping centre, whatever.
A hard limit on the number of any type of device is not good, especially if you make input packets have to fit into a machine word which makes extending the hard limit difficult (look at how long the 32 signal limit stayed around, causing problems with threading in apps which used SIGUSR1 for a user signal, such as squid, under the kernels with that limit).
USB supports something like 128 devices, there are also SCSI-based input devices you may want to incorporate into your scheme and so on. You can never predict the configurations where people might want to use Linux boxes.
I really don't like the idea of tagged input packets to begin with. What's the problem with a /dev/keyboard[#], /dev/joystick[#], /dev/mouse[#] and so on? Or even /dev/input[#] (which I don't particularly like the idea of). It's far more generic. It's simpler. It doesn't need a bloated inflexible protocol. Any application simply connects and gets only the information it wants.
David.
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