51 lines
2.1 KiB
Rust
51 lines
2.1 KiB
Rust
/*
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* SPDX-License-Identifier: BlueOak-1.0.0
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* Copyright (c) Berkus Decker <berkus+vesper@metta.systems>
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*/
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use {
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super::{CapError, Capability, TryFrom},
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crate::capdef,
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paste::paste,
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register::{register_bitfields, LocalRegisterCopy},
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};
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//=====================
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// Cap definition
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//=====================
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register_bitfields! {
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u128,
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// https://ts.data61.csiro.au/publications/csiro_full_text/Lyons_MAH_18.pdf
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// Resume objects, modelled after KeyKOS [Bomberger et al.1992], are a new object type
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// that generalise the “reply capabilities” of baseline seL4. These were capabilities
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// to virtual objects created by the kernel on-the-fly in seL4’s RPC-style call() operation,
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// which sends a message to an endpoint and blocks on a reply. The receiver of the message
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// (i.e. the server) receives the reply capability in a magic “reply slot” in its
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// capability space. The server replies by invoking that capability. Resume objects
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// remove the magic by explicitly representing the reply channel (and the SC-donation chain).
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// They also provide more efficient support for stateful servers that handle concurrent client
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// sessions.
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// The introduction of Resume objects requires some changes to the IPC system-call API.
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// The client-style call() operation is unchanged, but server-side equivalent, ReplyRecv
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// (previously ReplyWait) replies to a previous request and then blocks on the next one.
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// It now must provide an explicit Resume capability; on the send phase, that capability
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// identifies the client and returns the SC if appropriate, on the receive phase it is
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// populated with new values. The new API makes stateful server implementation more efficient.
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// In baseline seL4, the server would have to use at least two extra system calls to save the
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// reply cap and later move it back into its magic slot, removing the magic also removes
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// the need for the extra system calls.
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ResumeCap [
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Type OFFSET(0) NUMBITS(6) [
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value = 22
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]
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]
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}
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capdef! { Resume }
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//=====================
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// Cap implementation
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//=====================
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