Re: ioctl assignment strategy?

From: Chris Friesen
Date: Mon Dec 20 2004 - 12:39:18 EST

Greg KH wrote:

Rethink the way you want to control your device. Seriously, a lot of
ioctls can be broken down into single device files, single sysfs files,
or other such things (a whole new fs as a last resort too.)

Actually, my particular case is likely not a good example. We've got a misc char driver giving access to a lot of miscellaneous features we've added to the kernel,. We originally (a few years back) used new syscalls, but then we started supporting a bunch more arches, and having to patch all of them just to add syscall numbers sucked.

Some of it could easily be moved to /proc or /sys, but if you do it that way, how do you handle returning unusual error values? Other stuff involves multiple stages of registration, then getting handles returned, and doing new calls with those handles. I don't see how this would tie nicely into the read/write paradigm.

What's the big problem with ioctls anyways? I mean, in a closed environment where I'm writing both the userspace and the kernelspace side of things.

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