What is evdev and autoloading?

[Steve Kargl]

On Mon, Feb 18, 2019 at 09:35:26AM -0700, Warner Losh wrote:
> On Sun, Feb 17, 2019 at 3:52 PM Steve Kargl <
> sgk at troutmask.apl.washington.edu> wrote:
> 
> > Anyone have insight into what evdev is?  There appears to
> > be no manual page.  When I reboot a system with custom
> > kernel, the system is autoloading evdev.ko, uhid.ko, and
> > wmt.ko.  I do not need nor what these modules loaded.
> > How does one prevent this autoloading?
> >
> 
> 
> This thread has taken a weird turn, so I went back to the original post.
> 
> When do these things get loaded? Is it when you start up X11? Or is it
> being brought in by devmatch? If it is being brought in by x11, there's
> likely an x11 config that you'll need to avoid them (but that will reduce
> functionality). If it is devmatch, then you can add them to the black list
> and have them not load them.
> 

I think it is devmatch (or at least devd.conf related).
I have a wireless USB logitch mouse.  If I unplug the dongle
from its port and reboot, evdev.ko, uhid.ko, and wmt.ko do
not get loaded.  When I plug in the dongle, the 3 get loaded.
I can kldunload wmt and evdev, but as soon as the mouse is
moved both are reloaded.

ums(4) does not mention any of these devices as a requirement.
wmt(4) says it only works for touchscreen.  This laptop pre-dates
touchscreens, so loading the module is simply wasteful.  There
is no evdev(4), so can't determine what it is or does.

-- 
Steve