Hi Andrew,

On Wed, 2012-07-11 at 15:16 -0700, Andrew Morton wrote:

On Wed, 11 Jul 2012 15:01:32 -0700
Randy Dunlap [off-list ref] wrote:

quoted

In file included from drivers/staging/ccg/ccg.c:59:0:
drivers/staging/ccg/../../usb/gadget/f_fs.c:41:0: warning: "pr_vdebug" redefined
drivers/staging/ccg/../../usb/gadget/u_serial.c:138:0: note: this is the location of the previous definition

<looks at drivers/staging/ccg/ccg.c>

: /*
:  * Kbuild is not very cooperative with respect to linking separately
:  * compiled library objects into one module.  So for now we won't use
:  * separate compilation ... ensuring init/exit sections work to shrink
:  * the runtime footprint, and giving us at least some parts of what
:  * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
:  */
: #include "../../usb/gadget/usbstring.c"
: #include "../../usb/gadget/config.c"
: #include "../../usb/gadget/epautoconf.c"
: #include "../../usb/gadget/composite.c"
: 
: #include "../../usb/gadget/f_mass_storage.c"
: #include "../../usb/gadget/u_serial.c"
: #include "../../usb/gadget/f_acm.c"
: #define USB_ETH_RNDIS y
: #include "../../usb/gadget/f_rndis.c"
: #include "../../usb/gadget/rndis.c"
: #include "../../usb/gadget/u_ether.c"
: #include "../../usb/gadget/f_fs.c"

What nonsense is this?

Who wrote that rotten comment?  What does "not very cooperative" mean? 
This alleged lack of cooperation is the central issue, but you couldn't
be bothered actually describing it?  How the heck is anyone else to
understand the problem and suggest fixes?  argh.

It talks about library objects.  Really?  Is there a .a file
involved here, or is that just a thinko?  If there is indeed a .a file
then I'm not surprised there are problems: don't do that.  If instead
we're just talking about a bunch of .o files then I'm rather curious to
know what "not very cooperative" means.

I certainly won't attempt to defend this particular piece of code, but
FYI the original design limitation(s) for usb-gadget that requires this
type of strangeness was elaborated by Sebastian a few months back here:

http://www.spinics.net/lists/target-devel/msg02374.html

--nab