Questions about the USB HID device drivers

[Ian Lepore]

On Mon, 2019-02-18 at 15:03 -0600, Apollo D. Sharpe, Sr. via freebsd-
usb wrote:
> On 2/18/19 3:26 AM, Hans Petter Selasky wrote:
> > Each devicename has a uniq prefix followed by a uniq unit number.
> 
> So, we just end up dumping ALL device nodes in /dev...
> 
> 
> > Character device nodes are automatically created. However it is 
> > possible for user-space applications to create symbolic links 
> > afterwards in /dev .
> 
> ...and leave it to user-space to create the hierarchy within /dev?
> Is 
> there a technical reason that kernel drivers don't automatically 
> subscribe to a hierarchy, or is this just historic inertia? It seems 
> funny to me that such decisions are left to user-space applications.
> 
> 

Not to userland applications so much as to sysadmin-controlled
configuration which is applied from userland during system startup and when new devices are attached. See the manpage for devfs.conf.

>From the kernel side, some subsystems do create a hierarchy (or at
least a subdir for a set of related devices), and others don't. There
is no system-wide policy about it either way.

-- Ian