An early task is to specify a reference model for a Linux-Based Smartphone. A starting point is the functional model for a GSM/UMTS User Equipment (UE) as specified in TS 123.101.
The UE domain includes the smartphone device as well as all of the devices that plug into the device (like headsets and stereo earphones) as well as devices that are part of the users Personal Area Network (PAN). The reference model should account for these.
The model should also account for assistive technology devices used by people with disabilities as described in TS 102.511.
The present functional model shows TE within the ME. A more relevent model should have both a TE entity within the ME and external TE (an external PC/PDA or even other smartphone device).
There are User Interface (UI) paradigms with external wired or wireless displays, e.g. HDTV sets or goggles and various types of input devices. The reference model should be rich enough to account for all of these.
By definition a Linux smartphone includes a Linux kernel and device drivers, both kernel and (and possibly userspace). There is a clear and clean partition between kernel and user space that should probably be retained in the reference model.
The init process performs an important system management process in Linux systems. The init process should be part of the functional model along with its associated runlevel scripting.
Practical systems require some boot environment and possibly a resume environment for systems where hardware states are lost during suspend to RAM (or DISK). Both should be identified in the reference model. Both boot and resume drivers outside of kernel space should be accounted for.
Basic Security Issues of course need to be addressed.
I18n issues must be kept in mind especially support for CJK character sets and input methods, RTL text, and cursive scripts.
... what else - please add to this list or comment on the discussion page.