Re: 2.4.23-pre8: link error with multiple USB Gadget drivers

[David Brownell <david-b@pacbell.net>]

Adrian Bunk wrote:
> I'm getting the following link error when trying to compile multiple 
> Gadget drivers statically into the kernel:

... which is not a reasonable configuration, since only one
of them could be active ...

> ...
> IIRC this issue was fixed many months ago in 2.6, and a similar fix 
> (disallowing multiple Gadget drivers) is also needed in 2.4 .

Do you know a good way to do that?  This is an example of something
where the 2.4 "Config.in" commands don't seem to offer even a vaguely
sensible way to constrain the configuration.  Or maybe you need to
be more expert in it than I am.

The rules for the moment should -- but AFAICT can't -- enforce:

   - Only one gadget controller driver, linked statically or as
     a module.  (Example:  net2280 or goku_udc, both on PCI.)
   - If controller driver is statically linked, either:
        * at most one gadget driver statically linked
        * any number of gadget drivers, linked as modules
   - Else if controller driver is linked as a module:
        * any number of gadget drivers, linked as modules

The 2.6 Kconfig is closest to supporting those rules, though I
don't know how to restrict it to "only one controller driver"
regardless of how it's linked.

I'd be open to a better solution than relying on the person
configuring the system to not make mistakes.

- Dave