Re: two hotplug issues

[David Hinds]

Jeff Garzik wrote:
> I don't think that 'card_idx' is a good way to associate an interface to
> an instance of a PCI driver however...  A driver is well within its
> rights to export more than one interface to the world, for example a
> complex block device driver might export a character device for control
> purposes, so you don't even have a one-one correspondence between PCI
> driver instances and interfaces...

The old CardBus interface was set up so that a driver's attach() entry
point returned a linked list of device descriptors, of the form:

struct dev_node_t {
    char		dev_name[DEV_NAME_LEN];
    u_short		major, minor;
    struct dev_node_t	*next;
}

and this information was bounced out to user space.  Drivers would not
return every major/minor instance; they would return more or less one
per physical device, and let user space construct the rest.  A dual
network interface would return two dev_node_t structures; a hard drive
with N partitions would return one structure with the minor # for the
whole device; a multiport serial card would return the major/minor for
each callout device; etc.  Apart from implementation details like
kdev_t versus major/minor #'s, this might be a useful model.

-- Dave Hinds