FreeBSD Glossary

List of common terms and definitions that are used within the FreeBSD project, community and by its members.

ABI -- Application Binary Interface

Acronym: Application Binary Interface.

ABI compatibility is maintained (not changed) within FreeBSD major versions.



The "base" FreeBSD operating system – kernel and world. Everything that comes from and lives in the src repository 1

See Also: Local

CFT -- Call For Testing

Acronym: Call For Testing.

A call to action for the community to test something. Used on mailing lists, IRC, forums, Twitter and other communication channels.


Name given to the version of base in the src repository main branch. 2

Example: 14-CURRENT

Also known as: head, main

EN -- Errata Notice

Acronym: Errata Notice

Published notices that include patches, workarounds and other information about important bug or regression fixes for X.Y-RELEASE version of FreeBSD. Fixes are MFC'd to FreeBSD releng/x.y code branches.

See Also:

EXP-RUN -- Experimental Run

Acronym: Experimental Run

A test build of all ports run by portmgr using a specific proposed changeset or patch(es). Used to QA changes with large potential for regression/impact.


Linux compatibility layer in base that can run unmodified (native) Linux binaries.

Also known as: lemul (Linux Emulation).

More Information: Linuxulator


Everything that is installed separately, in addition to or after, and that is not, Base. In a nutshell, Ports and Packages. FreeBSD has a fairly strict separation of Base and Local, with base installed in / and Local installed (by default) in /usr/local, also known as LOCALBASE.

LOR -- Lock Order Reversal

Acronym: Lock Order Reversal.

See: LockOrderReversal

MFC -- Merge From Current

Acronym: Merge From Current.

Merging or back-porting a base commit from CURRENT (main/base/HEAD) to another, usually lower, FreeBSD version branch. Can be seen in commit log messages.

Example: MFC: After 2 weeks


MFH -- Merge From Head

Acronym: Merge From HEAD.

Merging or back-porting Ports commits from HEAD (main) to another (usually quarterly branch). Can be seen in commit log messages.

Example: MFH: 2020Q4

MFV -- Merge From Vendor

Acronym: Merge From Vendor.

Merging code from an external, upstream vendor repository into FreeBSD. Usually done with software that lives in src: contrib


A "pre-built" port containing compiled (binary) software artifacts, executables, libraries and documentation, usually in tbz or txz archives. Analogous to Debian 'packages'. These are the things you get (from package repositories) when you pkg install <package name>.


Project code review system, used for discussion and review of proposed changes to repositories. Sometimes referred to as Phab.

More Information: Phabricator


Recipes for automatically building and installing third-party software. Binary packages are produced from ports. Ports are analogous to Debian source packages.

Ports can be obtained and updated via portsnap or git

More Information: Ports


Tool for creating packages and testing ports.

See also: Poudriere GitHub Repository

PR -- Problem Report

Acronym: Problem Report.

An issue/bug report in Bugzilla. Seen in commit log messages to refer to an issue being worked on or resolved. When referenced in a commit log message, that commit log message is added to the issue as a comment.

Example: PR: 346543

More Information: Bugzilla

Acronym: Pull Request.



Ports repository branches created every 3 months (quarterly).

See Also: Ports/QuarterlyBranch

Releng -- Release Engineering

Acronym: Release Engineering.

Refers to base release code branches. Release branches receive important bugfixes (via Errata Notices) and security fixes (via Security Advisories).

Example: releng/13.1 the release branch for FreeBSD 13.1-RELEASE.

SA -- Security Advisory

Acronym: Security Advisory

Published notifications for security vulnerabilities and fixes that include patches, workarounds, and other information for X.Y-RELEASE version of FreeBSD. Fixes are MFC'd to FreeBSD releng/x.y code branches.

See Also:


Version label given to FreeBSD (src) major versions in stable/* repository branches.

Means: A stable ABI within that branch, not the common or dictionary stability meaning.

Examples: 13-STABLE (Code branch: stable/13)

See Also:

  1. This was the base SVN repository, before git (1)

  2. This was the HEAD branch of base in SVN, before git (2)

Glossary (last edited 2022-10-22T01:41:07+0000 by KubilayKocak)