200 lines
8.6 KiB
ReStructuredText
200 lines
8.6 KiB
ReStructuredText
.. _glossary:
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Glossary of Terms
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#################
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.. glossary::
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:sorted:
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AaaG
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LaaG
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WaaG
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Acronyms for Android, Linux, and Windows as a Guest VM. ACRN supports a
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variety of :term:`User VM` OS choices. Your choice depends on the
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needs of your application. For example, Windows is popular for
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Human-Machine Interface (HMI) applications in industrial applications,
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while Linux is a likely OS choice for a VM running an AI application.
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ACPI
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Advanced Configuration and Power Interface
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ACRN
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ACRN is a flexible, lightweight reference hypervisor, built with
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real-time and safety-criticality in mind, optimized to streamline
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embedded development through an open source platform.
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API
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Application Program Interface: A defined set of routines and protocols for
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building application software.
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APL
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Apollo Lake platform
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BDW
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Broadwell, Intel 5th-generation CPU platform
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BIOS
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Basic Input/Output System.
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DM
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Device Model
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An application within the Service VM responsible for creating and
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launching a User VM and then performing device emulation for the devices
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configured for sharing with that User VM. The Service VM and Device Model
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can access hardware resources directly through native drivers and provide
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device sharing services to User VMs. User VMs can access hardware devices
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directly if they've been configured as passthrough devices.
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Development Computer
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Host
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As with most IoT development environments, you configure, compile, and
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build your application on a separate system from where the application is
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deployed and run (i.e., the :term:`Target`). ACRN recommends using Ubuntu
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18.04 as the OS on your development computer and that is an assumption in
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our documentation.
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Guest
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Guest VM
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A term used to refer to any :term:`VM` that runs on the hypervisor. Both Service
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and User VMs are considered Guest VMs from the hypervisor's perspective,
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albeit with different properties. *(You'll find the term Guest used in the
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names of functions and variables in the ACRN source code.)*
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GVT-d
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Virtual dedicated graphics acceleration (one VM to one physical GPU).
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Hybrid
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One of three operation scenarios (partitioned, shared, and hybrid) that ACRN supports.
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In the hybrid mode, some physical hardware resources can be partitioned to
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individual User VMs while others are shared across User VMs.
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IDT
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Interrupt Descriptor Table: a data structure used by the x86
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architecture to implement an interrupt vector table. The IDT is used
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to determine the correct response to interrupts and exceptions.
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ISR
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Interrupt Service Routine: Also known as an interrupt handler, an ISR
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is a callback function whose execution is triggered by a hardware
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interrupt (or software interrupt instructions) and is used to handle
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high-priority conditions that require interrupting the code currently
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executing on the processor.
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Passthrough Device
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Physical I/O devices (typically PCI) exclusively assigned to a User VM so
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that the VM can access the hardware device directly and with minimal (if any)
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VM management involvement. Normally, the Service VM owns the hardware
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devices shared among User VMs and virtualized access is done through
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Device Model emulation.
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Partitioned
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One of three operation scenarios (partitioned, shared, and hybrid) that ACRN supports.
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Physical hardware resources are dedicated to individual User VMs.
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Pre-launched VM
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A :term:`User VM` launched by the hypervisor before the :term:`Service VM`
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is started. Such a User VM runs independently of and is partitioned from
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the Service VM and other post-launched VMs. It has its own carefully
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configured and dedicated hardware resources such as CPUs, memory, and I/O
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devices. Other VMs, including the Service VM, may not even be aware of a
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pre-launched VM's existence. A pre-launched VM can be used as a
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special-case :term:`Safety VM` for reacting to critical system failures.
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It cannot take advantage of the Service VM or Device Model services.
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Post-launched VM
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A :term:`User VM` configured and launched by the Service VM and typically
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accessing shared hardware resources managed by the Service VM and Device
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Model. Most User VMs are post-launched while special-purpose User VMs are
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pre-launched.
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QEMU
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Quick EMUlator. Machine emulator running in user space.
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RDT
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Intel Resource Director Technology (Intel RDT) provides a set of
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monitoring and allocation capabilities to control resources such as
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Cache and Memory. ACRN supports Cache Allocation Technology (CAT) and
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Memory Bandwidth Allocation (MBA).
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RTVM
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Real-time VM
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A :term:`User VM` configured specifically for real-time applications and
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their performance needs. ACRN supports near bare-metal performance for a
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post-launched real-time VM by configuring certain key technologies or
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enabling device-passthrough to avoid common virtualization and
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device-access overhead issues. Such technologies include: using a
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passthrough interrupt controller, polling-mode Virtio, Intel RDT
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allocation features (CAT, MBA), and I/O prioritization. RTVMs are
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typically a :term:`Pre-launched VM`. A non-:term:`Safety VM` with
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real-time requirements is a :term:`Post-launched VM`.
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Safety VM
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A special VM with dedicated hardware resources for providing overall
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system health-monitoring functionality. A safety VM is always a
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pre-launched User VM, either in a partitioned or hybrid scenario.
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Scenario
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A collection of hypervisor and VM configuration settings that define an
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ACRN-based application's environment. A scenario configuration is stored
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in a scenario XML file and edited using the ACRN configurator tool. The
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scenario configuration, along with the target board configuration, is used
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by the ACRN build system to modify the source code to build tailored
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images of the hypervisor and Service VM for the application. ACRN provides
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example scenarios for shared, partitioned, and hybrid configurations that
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developers can use to define a scenario configuration appropriate for
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their own application.
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Service VM
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A special VM, directly launched by the hypervisor. The Service VM can
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access hardware resources directly by running native drivers and provides
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device sharing services to post-launched User VMs through the ACRN Device
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Model (DM). Hardware resources include CPUs, memory, graphics memory, USB
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devices, disk, and network mediation. *(Historically, the Service VM was
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called the Service OS or SOS.)*
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Shared
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One of three operation scenarios (shared, hybrid, partitioned) that ACRN supports.
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Most of the physical hardware resources are shared across User VMs.
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*(In releases prior to 2.7, this was called the "Industry" scenario.)*
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Target
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This is the hardware where the configured ACRN hypervisor and
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developer-written application (built on the :term:`Development Computer`) is
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deployed and runs.
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UEFI
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Unified Extensible Firmare Interface. UEFI replaces the
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traditional BIOS on PCs, while also providing BIOS emulation for
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backward compatibility. UEFI can run in 32-bit or 64-bit mode and, more
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important, support Secure Boot, checking the OS validity to ensure no
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malware has tampered with the boot process.
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User VM
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A :term:`VM` where user-defined environments and applications run. User VMs can
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run different OSes based on their needs, including for example, Ubuntu for
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an AI application, Android or Windows for a Human-Machine Interface, or a
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hard real-time control OS such as Zephyr, VxWorks, or RT-Linux for soft or
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hard real-time control. There are three types of ACRN User VMs: pre-launched,
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post-launched standard, and post-launched real-time. *(Historically, a
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User VM was also called a User OS, or simply UOS.)*
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VM
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Virtual Machine
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A compute resource that uses software instead of physical hardware to run a
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program. Multiple VMs can run independently on the same physical machine,
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and with their own OS. A hypervisor uses direct access to the underlying
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machine to create the software environment for sharing and managing
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hardware resources.
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VMM
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Virtual Machine Monitor
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VMX
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Virtual Machine Extension
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VT
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Intel Virtualization Technology
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VT-d
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Virtualization Technology for Directed I/O
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