Apps with Hardware: Enabling Run-time Architectural Customization in Smart Phones

In this paper we present a novel system which incorporates programmable hardware (an FPGA) into a smartphone to enable a vision where apps can include both software and hardware components, or apps with hardware. We introduce a novel mechanism to enable sharing the FPGA in a practical manner by leveraging the unique deployment model of mobile applications - namely that deployment is via an app store, where we introduce a new cloud-based compilation. We present our prototype smart phone using the Zedboard, which pairs a Xilinx Zynq FPGA with an embedded Cortex A9, running an Android-based system which we extended to provide run-time system support for dynamically managing apps with hardware and providing a secure loading system. With this prototype, our evaluation demonstrates the performance gains for an AES encryption module (representing cryptography), a QAM modulation module (representing software-defined radio) of 3x to several orders of magnitude, with room for improvement and a hardware-based memory scanner (representing custom co-processors). We demonstrate the feasibility of our cloud-based compilation within the context of real app store statistics. Finally, we present a case study of a complete integration of hardware into an existing application (the Orbot Tor client).