loadable drivers and user controlled attach/detach of devices.
An outline was given in
http://mail-index.NetBSD.org/tech-kern/2004/08/11/0000.html
To cite the relevant parts:
-Add a "child detached" and a "rescan" method (both optional)
to the device driver. (This is added to the "cfattach" for now
because this is under the driver writer's control. Logically
it belongs more to the "cfdriver", but this is automatically
generated now.)
The "child detached" is called by the autoconf framework
during config_detach(), after the child's ca_detach()
function was called but before the device data structure
is freed.
The "rescan" is called explicitely, either after a driver LKM
was loaded, or on user request (see the "control device" below).
-Add a field to the device instance where the "locators" (in
terms of the autoconf framework), which describe the actual
location of the device relatively to the parent bus, can be
stored. This can be used by the "child detached" function
for easier bookkeeping (no need to lookup by device instance
pointer). (An idea for the future is to use this for generation
of optimized kernel config files - like DEC's "doconfig".)
-Pass the locators tuple describing a device's location to
various autoconf functions to support the previous. And since
locators do only make sense in relation to an "interface
attribute", pass this as well.
-Add helper functions to add/remove supplemental "cfdata"
arrays. Needed for driver LKMs.
There is some code duplication which will hopefully resolved
when all "submatch"-style functions are changed to accept the
locator argument.
Some more cleanup can take place when config(8) issues more
information about locators, in particular the length and default
values. To be done later.
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