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@xxxxxxxxx> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
