FYI: FunctionFS - using adbd with a generic FunctionFS gadget instead of a custom adb usb gadget

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Jim Huang

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Mar 12, 2012, 3:40:09 PM3/12/12

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Hello list,

Andrzej Pietrasiewicz of Samsung submitted an interesting patch about
FunctionFS:
https://android-review.googlesource.com/#/c/31640/

It demonstrates the possibility of using adbd (Android Debug Bridge
daemon) with
a generic FunctionFS gadget instead of a custom adb usb gadget in the
Linux kernel.

The patch adds a replacement usb access layer to adbd: it adds a new layer as
a copy of an existing usb_linux_client.c and introduces
FunctionFS support proper on top of the copied layer. The former usb access
method is still available, the method is chosen at compilation time by
setting USE_USB_FUNCFS variable to false in adb's Android.mk in the section
dedicated to adbd.

How to use on the target device:

$ insmod g_ffs.ko idVendor=<vendor ID> iSerialNumber=<some string>
$ mount -t functionfs adb /dev/usbgadget/adb -o uid=2000,gid=2000
$ ./adbd