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Introduction to Dovetail
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:Author: Philippe Gerum
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:Date: 08.04.2020
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Using Linux as a host for lightweight software cores specialized in
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delivering very short and bounded response times has been a popular
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way of supporting real-time applications in the embedded space over
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the years.
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In this so-called *dual kernel* design, the time-critical work is
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immediately delegated to a small companion core running out-of-band
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with respect to the regular, in-band kernel activities. Applications
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run in user space, obtaining real-time services from the
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core. Alternatively, when there is no real-time requirement, threads
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can still use the rich GPOS feature set Linux provides such as
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networking, data storage or GUIs.
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*Dovetail* introduces a high-priority execution stage into the main
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kernel logic reserved for such a companion core to run on. At any
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time, out-of-band activities from this stage can preempt the common,
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in-band work. A companion core can be implemented as as a driver,
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which connects to the main kernel via the Dovetail interface for
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delivering ultra-low latency scheduling capabilities to applications.
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Dovetail is fully described at https://evlproject.org/dovetail/.
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The reference implementation of a Dovetail-based companion core is
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maintained at https://evlproject.org/core/.
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