Re: Game Controllers

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Thu, May 02, 2013 at 03:54:45PM -0400, Todd Showalter wrote:
> On Thu, May 2, 2013 at 2:29 PM, Dmitry Torokhov
> <dmitry.torokhov@gmail.com> wrote:
> 
> >> - any mapping library is going to have to be a mirror of the kernel
> >> code, which means it's basically just a lot of duplicated effort with
> >> the added penalty of update lag
> >
> > The library can do much more than that. You also need to calibrate the
> > device (per user), adjust it to user's tastes and so on. Maybe you have
> > a user that is left-handed and you'd like to remap some keys? It is
> > certainly not kernel's job.
> 
>     I think calibration, dead-zones, easing, button remapping and the
> like are a totally orthogonal problem.  They are nice to have, but
> that's the kind of thing that belongs in a desktop environment's
> accessibility settings, not at the input protocol level.
> 
> > There also should not be lag if new devices follow the agreed upon
> > mapping.
> 
>     If we can have that, at least, it means the problem is eventually
> fixed.  Maybe not for years, but at least someday.
> 
> > The same thing can be done in a library. Libraries are easier then
> > kernels, you do not need to consume memory until needed and you do not
> > need to do the conversion if it is not needed. And it should be possible
> > to update the library whereas with kernel you mist likely need to reboot
> > the box.
> >
> > Why do people believe that patching the kernel is easier than updating
> > userspace?
> 
>     The kernel is the core of the system; Linux isn't Linux without
> the Linux kernel.  If I make a game input library and try to get
> people to use it, there's a whole chicken-and-egg problem of getting
> developers to support something nobody has installed, and getting
> users to install something no developers support.  I have to convince
> the distros to pick it up, and to keep updating it.  I have to monitor
> changes in the kernel codebase to see if the library needs updating.
> I have to deal with the possibility that the library becomes a useful
> bandaid, with people saying "meh, this is a hard problem, punt the fix
> to the library".  I have to hope that telling players to install
> another dependency isn't going to lose me customers.

Until you get a traction with the new you might need to distribute it
with your game. Another option would be to extend already established
library, such as SDL, with the required functionality.

> 
>     The kernel has authority that a library does not, and it has a
> distribution mechanism that a library does not.  The kernel is
> effectively the source of the data; all I can do outside of that is
> provide a filter and hope people use it.

No, I do not think so. Kernel provides a level of abstraction, but so
does X, ALSA, given desktop environment and so forth. If a task does not
require hardware access (and translating input events form one type to
another does not) one should think really hard whether it should be
done in kernel.

Thanks.

-- 
Dmitry