AFAIK STM32F7 chips are not yet supported by the standard OpenOCD code base, and most certainly not by the gnuarmeclipse toolset; this forum is to support System Workbench for STM32, another IDE explicitly targeting the STM32 family and with which we support all STM32 chips, as soon as they are officially available (well not always immediately: it may takes a couple of days for the support to be available )
In this process we have to develop the configuration scripts and, more complicated, enhance OpenOCD to support the new chips. As OpenOCD is licensed under the GPL, you can get the source code for our OpenOCD version on git://git.ac6.fr/openocd.git ; the binary version and the scripts are part of System Workbench for STM32.
Clearly, if you want to work on the latest chips and boards from ST, why don’t you give a try at System Workbench for STM32? It’s based on a standard Ecipse platform (not a specific Eclipse version), so you should not be too confused, and it’s totally free too...
Otherwise, if you really want to stick to gnuarmeclipse, this is not the right forum to ask questions, sorry