Also don't expect this "hypervisor" to be a complete software package like Xen or VMware. I'm speculating here, but all that's needed is a rather fixed allocati

Also don't expect this "hypervisor" to be a complete software package like Xen or VMware. I'm speculating here, but all that's needed is a rather fixed allocation of peripherals, interrupts and RAM for each guest (radio+SIM+a few MB RAM to baseband, everything else to Android), likely compiled statically for this particular platform. No fancy emulation of hardware or device-drivers giving paravirtualized access to complicated peripherals necessary. In that case, and with a CPU and peripherals designed with keeping this concept in mind, the overhead will be almost non-existant compared to, for example, running the baseband functionality as a "regular kernel module"; with the added advantage of clearly separating both worlds, and isolating the realtime-requirements of the baseband from the Linux kernel. For some similar concept, have a loot at "RTlinux", where the Linux-Kernel runs as the lowest-priority task in a very thin realtime-OS to achieve guaranteed reaction times for, e.g. motor control applications. http://en.wikipedia.org/wiki/RTLinux http://en.wikipedia.org/wiki/RTLinux