Re: A cleaner load_drivers function.

[Stamatis Mitrofanis <ewstam@softhome.net>]

Stamatis Mitrofanis wrote:

 > To put it more clearly: just load the module _unless_ there exists
 > /etc/hotplug/TYPE/DRIVER.agent  to delegate to.
 >
 > Note the `.agent' extension!
 >
 > IMO, this driver-agent interface is much more forward-looking and
 > uniform. You just can't exclude the possibility that a driver may want
 > to do something device-specific in user-space _before_ `modprobe'ing.

The driver-specific agents can do some _additional filtering_ this way.
  (I forgot that -- why do I keep forgetting to mention things? :-( )

The input subsystem can be an example. It has many bitmasks, some more
than 32 bits.

ACTION ... add|remove
PRODUCT ... idbus/idvendor/idproduct/idversion
NAME ... Device name from device descriptor.
PHYS ... pci00:07.2/usb0:2.3/input0 (device physical address ID).
EV ... Bitmask (32 bits) for the kinds of events this device supports.
KEY ... 511 bits for the keys&buttons the device has.
REL ... 15 bits for relative axes (x/y/z, mouse-wheel etc.) it provides.
ABS ... 31 bits for absolute axes (x/y/z, throttle, pressure etc.).
LED ... 15 bits for the LEDs on the device (num/caps-lock etc.).
SND ... 7 bits for the characteristic sounds the device can make (beep!).
FF ... 127 bits for supported force-feedback effects!
MSC ... 7 more bits for the rest.

It would be great if the input-driver-specific agents could do some
extra filtering as appropriate.

/****/

Here is a _tiny_ patch that will make load_drivers delegate (full
backward compatibility):

diff -r linux-hotplug/etc/hotplug/hotplug.functions
linux-hotplug2/etc/hotplug/hotplug.functions
123a124,130
  >     # Available driver-specific agent?
  >     if [ -f "/etc/hotplug/$TYPE/$MODULE.agent" -a \
  >          -x "/etc/hotplug/$TYPE/$MODULE.agent" ]; then
  >         "/etc/hotplug/$TYPE/$MODULE.agent"
  >         continue
  >     fi
  >

Now, the driver-specific agent (if available) can handle `add' events
for devices it most likely handles. It can forget about devices it
doesn't really handle.

It would be a good idea to extend the `load_drivers' interface so that
it handles `remove' events as well.




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