Using an Davicom 9601 based USB-Ethernet-Adapter with the Nexus 7

Some weeks ago I bought an USB ethernet adapter on Amazon. Unfortunately that adapter is not working with the Nexus 7, because the chipset is not supported by the kernel out of the box.
I found out, that the USB-Adapter (JP1082) is based on the Davicom 9601 chipset, which principally is supported by the linux kernel, so I decided to build a kernel which is supporting that adapter.

I did a git clone of the nexus 7 kernel sources from https://android.googlesource.com/kernel/tegra and a checkout of the latest kernel branch

git checkout android-tegra3-grouper-3.1-jb-mr1.1

after running

make ARCH=arm tegra3_android_defconfig

to create the default nexus kernel configuration the Davicom adapter needs to be added to the configuration by opening .config and changing the line

# CONFIG_USB_NET_DM9601 is not set

to

CONFIG_USB_NET_DM9601=y

Now the kernel is ready to be built:

make ARCH=arm zImage

after a successfull compilation the kernel can be booted by

fastboot boot arch/arm/boot/zImage

After booting the device and connecting the USB-ethernet adapter to the OTG-cable, you need to open a terminal window and call

/system/bin/dhcpcd eth0

to configure the ethernet link. That's all!