Linked by Thom Holwerda on Tue 12th Nov 2013 23:06 UTC
PDAs, Cellphones, Wireless

I've always known this, and I'm sure most of you do too, but we never really talk about it. Every smartphone or other device with mobile communications capability (e.g. 3G or LTE) actually runs not one, but two operating systems. Aside from the operating system that we as end-users see (Android, iOS, PalmOS), it also runs a small operating system that manages everything related to radio. Since this functionality is highly timing-dependent, a real-time operating system is required.

This operating system is stored in firmware, and runs on the baseband processor. As far as I know, this baseband RTOS is always entirely proprietary. For instance, the RTOS inside Qualcomm baseband processors (in this specific case, the MSM6280) is called AMSS, built upon their own proprietary REX kernel, and is made up of 69 concurrent tasks, handling everything from USB to GPS. It runs on an ARMv5 processor.

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Real-Time Linux
by robbrowsing on Thu 14th Nov 2013 03:04 UTC
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Perhaps this is tangential, but I just read this article on the decline of Real-Time Linux.

It would be nice if you could have "one kernel to rule them all" - i.e. nearly all functions in a phone handled using the Linux kernel. But I don't think that will ever happen or would be desirable/feasible in any case?

I don't think RT Linux would ever be a good fit for Mobile Phones but it's still a great project for other uses, so its loss would be sad. Maybe somebody more knowledgeable would like to disagree with me?

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