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diff --git a/content.tex b/content.tex index 1d7cc91..e450d88 100644 --- a/content.tex +++ b/content.tex @@ -1,86 +1,3 @@ -\chapter{INTRODUCTION}\label{sec:INTRODUCTION} - -This document describes the specifications of the “virtio” family of -devices. These are devices are found in virtual environments, yet by -design they are not all that different from physical devices, and this -document treats them as such. This allows the guest to use standard -drivers and discovery mechanisms. - -The purpose of virtio and this specification is that virtual -environments and guests should have a straightforward, efficient, -standard and extensible mechanism for virtual devices, rather -than boutique per-environment or per-OS mechanisms. - - Straightforward: Virtio devices use normal bus mechanisms of - interrupts and DMA which should be familiar to any device driver - author. There is no exotic page-flipping or COW mechanism: it's just - a normal device. -\footnote{This lack of page-sharing implies that the implementation of the -device (e.g. the hypervisor or host) needs full access to the -guest memory. Communication with untrusted parties (i.e. -inter-guest communication) requires copying. -} - - Efficient: Virtio devices consist of rings of descriptors - for input and output, which are neatly separated to avoid cache - effects from both guest and device writing to the same cache - lines. - - Standard: Virtio makes no assumptions about the environment in which - it operates, beyond supporting the bus attaching the device. Virtio - devices are implemented over PCI and other buses, and earlier drafts - been implemented on other buses not included in this spec. -\footnote{The Linux implementation further separates the PCI virtio code -from the specific virtio drivers: these drivers are shared with -the non-PCI implementations (currently lguest and S/390). -} - - Extensible: Virtio PCI devices contain feature bits which are - acknowledged by the guest operating system during device setup. - This allows forwards and backwards compatibility: the device - offers all the features it knows about, and the driver - acknowledges those it understands and wishes to use. - -\section{Key words}\label{sec:Key words} - -The key words must, must not, required, shall, shall not, should, -should not, recommended, may, and optional are to be interpreted as -described in [RFC 2119]. Note that for reasons of style, these words -are not capitalized in this document. - -\section{Definitions}\label{sec:Definitions} - -term - Definition - -\section{Key concepts}\label{sec:Key concepts} - -Guest - Definition... - -Host - Definition - -Device - Definition - -Driver - Definition - -\chapter{Normative References}\label{sec:Normative References} - -[RFC 2119] S. Bradner, Key words for use in RFCs to Indicate Requirement Levels, http://www.ietf.org/rfc/rfc2119.txt IETF (Internet Engineering Task Force) RFC 2119, March 1997. - -[S390 PoP] z/Architecture Principles of Operation, IBM Publication SA22-7832 - -[S390 Common I/O] ESA/390 Common I/O-Device and Self-Description, IBM Publication SA22-7204 - -\chapter{Non-Normative References}\label{sec:Non-Normative References} - - - -\chapter{The Virtio Standard}\label{sec:The Virtio Standard} - \chapter{Basic Facilities of a Virtio Device}\label{sec:Basic Facilities of a Virtio Device} A virtio device is discovered and identified by a bus-specific method |