This glossary contains terms and acronyms used within the FreeBSD community and documentation.
See: Access Control List
See: ACPI Source Language
Pseudocode, interpreted by a virtual machine within an ACPI-compliant operating system, providing a layer between the underlying hardware and the documented interface presented to the OS.
The programming language AML is written in.
A list of permissions attached to an object, usually either a file or a network device.
A specification which provides an abstraction of the interface the hardware presents to the operating system, so that the operating system should need to know nothing about the underlying hardware to make the most of it. ACPI evolves and supersedes the functionality provided previously by APM, PNPBIOS and other technologies, and provides facilities for controlling power consumption, machine suspension, device enabling and disabling, etc.
A set of procedures, protocols and tools that specify the canonical interaction of one or more program parts; how, when and why they do work together, and what data they share or operate on.
An API enabling the operating system to work in conjunction with the BIOS in order to achieve power management. APM has been superseded by the much more generic and powerful ACPI specification for most applications.
A daemon that automatically mounts a filesystem when a file or directory within that filesystem is accessed.
The registers that determine which address range a PCI device will respond to.
The definition of BIOS depends a bit on the context. Some people refer to it as the ROM chip with a basic set of routines to provide an interface between software and hardware. Others refer to it as the set of routines contained in the chip that help in bootstrapping the system. Some might also refer to it as the screen used to configure the boostrapping process. The BIOS is PC-specific but other systems have something similar.
An implementation of the DNS protocols.
This is the name that the Computer Systems Research Group (CSRG) at The University of California at Berkeley gave to their improvements and modifications to AT&T's 32V UNIX®. FreeBSD is a descendant of the CSRG work.
A phenomenon whereby many people will give an opinion on an uncomplicated topic, whilst a complex topic receives little or no discussion. See the FAQ for the origin of the term.
See: Carrier Detect
See: Clear To Send
An RS232C signal indicating that a carrier has been detected.
Also known as the processor. This is the brain of the computer where all calculations take place. There are a number of different architectures with different instruction sets. Among the more well-known are the Intel-x86 and derivatives, Sun SPARC, PowerPC, and Alpha.
A method of authenticating a user, based on a secret shared between client and server.
An RS232C signal giving the remote system permission to send data.
See Also: Request To Send.
A version control system, providing a method of working with and keeping track of many different revisions of files. CVS provides the ability to extract, merge and revert individual changes or sets of changes, and offers the ability to keep track of which changes were made, by who and for what reason.
See: Debugger
See: Domain Name System
See: Data Set Ready
See: Data Terminal Ready
A method of encrypting information, traditionally used as the method of encryption for UNIX passwords and the crypt(3) function.
An RS232C signal sent from the modem to the computer or terminal indicating a readiness to send and receive data.
See Also: Data Terminal Ready.
An RS232C signal sent from the computer or terminal to the modem indicating a readiness to send and receive data.
An interactive in-kernel facility for examining the status of a system, often used after a system has crashed to establish the events surrounding the failure.
An ACPI table, supplying basic configuration information about the base system.
The system that converts humanly readable hostnames (i.e., mail.example.net) to Internet addresses and vice versa.
A protocol that dynamically assigns IP addresses to a computer (host) when it requests one from the server. The address assignment is called a lease.
See: Extended COFF
The name of a mutual exclusion mechanism (a sleep mutex) that protects a large set of kernel resources. Although a simple locking mechanism was adequate in the days where a machine might have only a few dozen processes, one networking card, and certainly only one processor, in current times it is an unacceptable performance bottleneck. FreeBSD developers are actively working to replace it with locks that protect individual resources, which will allow a much greater degree of parallelism for both single-processor and multi-processor machines.
A system where the user and computer interact with graphics.
See: HangUp
The markup language used to create web pages.
See: Input/Output
See: Intel's ASL compiler
See: Internet Protocol
See: IP Firewall
See: IP Version 4
See: IP Version 6
The IP protocol version 4, which uses 32 bits for addressing. This version is still the most widely used, but it is slowly being replaced with IPv6.
See Also: IP Version 6.
The new IP protocol. Invented because the address space in IPv4 is running out. Uses 128 bits for addressing.
Intel's compiler for converting ASL into AML.
A protocol for accessing email messages on a mail server, characterised by the messages usually being kept on the server as opposed to being downloaded to the mail reader client.
See Also: Post Office Protocol Version 3.
The packet transmitting protocol that is the basic protocol on the Internet. Originally developed at the U.S. Department of Defense and an extremely important part of the TCP/IP stack. Without the Internet Protocol, the Internet would not have become what it is today. For more information, see RFC 791.
A company that provides access to the Internet.
Japanese for turtle, the term KAME is used in computing circles to refer to the KAME Project, who work on an implementation of IPv6.
See: Kilo Bits Per Second
A method of dynamically loading functionality into a FreeBSD kernel without rebooting the system.
A kernel-supported threading system. See the project home page for further details.
Used to measure bandwidth (how much data can pass a given point at a specified amount of time). Alternates to the Kilo prefix include Mega, Giga, Tera, and so forth.
See: Local Area Network
See: Lock Order Reversal
See: Line Printer Daemon
A network used on a local area, e.g. office, home, or so forth.
The FreeBSD kernel uses a number of resource locks to arbitrate contention for those resources. A run-time lock diagnostic system found in FreeBSD-CURRENT kernels (but removed for releases), called witness(4), detects the potential for deadlocks due to locking errors. (witness(4) is actually slightly conservative, so it is possible to get false positives.) A true positive report indicates that if you were unlucky, a deadlock would have happened here.
True positive LORs tend to get fixed quickly, so check http://lists.FreeBSD.org/mailman/listinfo/freebsd-current and the LORs Seen page before posting to the mailing lists.
See: Merge From Current
See: Merge From Perforce
See: Merge From Stable
See: Multi-Level Security
See: Message Of The Day
See: Mail Transfer Agent
See: Mail User Agent
An application used to transfer email. An MTA has traditionally been part of the BSD base system. Today Sendmail is included in the base system, but there are many other MTAs, such as postfix, qmail and Exim.
An application used by users to display and write email.
To merge functionality or a patch from the -CURRENT branch to another, most often -STABLE.
To merge functionality or a patch from the Perforce repository to the -CURRENT branch.
See Also: Perforce.
In the normal course of FreeBSD development, a change will be committed to the -CURRENT branch for testing before being merged to -STABLE. On rare occasions, a change will go into -STABLE first and then be merged to -CURRENT.
This term is also used when a patch is merged from -STABLE to a security branch.
See Also: Merge From Current.
A message, usually shown on login, often used to distribute information to users of the system.
See: Project Evil
See: Network File System
A technique where IP packets are rewritten on the way through a gateway, enabling many machines behind the gateway to effectively share a single IP address.
A filesystem developed by Microsoft and available in its New Technology operating systems, such as Windows® 2000, Windows NT® and Windows XP.