40.5 GENERIC Kernel Options (AMD64)

GENERIC is the default kernel configuration file for the FreeBSD amd64 architecture, and its options can all be found with corresponding descriptions in the machine-independent and machine-dependent NOTES files. This section lists the complete GENERIC options with item-by-item annotations.

For detailed option lists and device line descriptions, refer to the corresponding NOTES file.

The original meaning of GENERIC is "general-purpose, generic, common." The GENERIC kernel options are the default build options for all images under the amd64 architecture (FreeBSD/amd64 generic kernel configuration file), but CURRENT (main branch) introduces additional debugging options.

For ease of explanation and to avoid introducing debugging options that are useless to most non-developers, this section uses the GENERIC kernel options from 15.0-RELEASE (releng/15.0 branch) as an example.

• Source: sys/amd64/conf/GENERIC
• Version: u2f(4): Invert U2F_MAKE_UHID_ALIAS kernel build option, nearly 400 lines in total

First, the CPU-related configuration options:

cpu		HAMMER

HAMMER is the codename for AMD K8, namely Opteron and Athlon64.

ident		GENERIC

This is the kernel "identifier."

It should typically be the same as the kernel name. This option sets the kernel name to GENERIC. At least one ident entry is required.

makeoptions	DEBUG=-g

Build a kernel that includes gdb(1) debugging symbols.

makeoptions	WITH_CTF=1

To support DTrace, run ctfconvert(1) to convert debug data into CTF data.

options 	SCHED_ULE

ULE scheduler.

options 	NUMA

Non-Uniform Memory Access (NUMA) support.

options 	PREEMPTION

Enable kernel thread preemption.

options 	EXTERR_STRINGS

Its former name was BLOAT_KERNEL_WITH_EXTERR, used to enable extended kernel error messages. See: Extended errors from kernel[EB/OL]. [2026-03-26]. https://reviews.freebsd.org/D50483.

options 	VIMAGE

Used for subsystem virtualization, such as VNET.

options 	INET

IPv4 protocol family. The IP protocol family is a set of protocols layered above the Internet Protocol (IP) and using the Internet address format. This protocol family provides protocol support for SOCK_STREAM, SOCK_DGRAM, and SOCK_RAW socket types; the SOCK_RAW interface provides access to the IP protocol.

options 	INET6

IPv6 protocol family.

options 	IPSEC_SUPPORT

Allow loading ipsec and tcpmd5 modules via the kldload command.

options 	IPSEC_OFFLOAD

Inline IPsec offload infrastructure.

options 	ROUTE_MPATH

Multipath routing support.

options 	FIB_ALGO

Modular FIB lookup support.

options 	TCP_OFFLOAD

TCP offload support.

options 	TCP_BLACKBOX

Enhanced TCP event logging.

options 	TCP_HHOOK

hhook(9) framework support for TCP.

options 	TCP_RFC7413

TCP Fast Open.

options 	SCTP_SUPPORT

Allow loading SCTP KLD module support.

options 	KERN_TLS

TLS send and receive offload.

options 	FFS

Berkeley Fast File System (FFS).

options 	SOFTUPDATES

Enable FFS soft updates support.

options 	UFS_ACL

Access control list support.

options 	UFS_DIRHASH

Improve performance for large directories.

options 	UFS_GJOURNAL

Enable gjournal-based UFS journaling.

options 	QUOTA

Enable UFS disk quotas.

options 	MD_ROOT

Allow MD devices to serve as the root device.

options 	NFSCL

Network File System (NFS) client.

options 	NFSD

Network File System (NFS) server.

options 	NFSLOCKD

Network Lock Manager (NLM).

options 	NFS_ROOT

Use NFS as /, depends on NFSCL.

options 	MSDOSFS

MS-DOS file system.

options 	CD9660

ISO 9660 file system.

options 	PROCFS

Proc process file system (requires PSEUDOFS support).

options 	PSEUDOFS

Pseudo-file system framework.

options 	TMPFS

Efficient memory file system.

options 	GEOM_RAID

Software RAID support.

options 	GEOM_LABEL

Provides GEOM label functionality.

options 	EFIRT

EFI runtime services support.

options 	COMPAT_FREEBSD32

i386 binary compatibility.

options 	COMPAT_FREEBSD4

FreeBSD 4 compatibility.

options 	COMPAT_FREEBSD5

FreeBSD 5 compatibility.

options 	COMPAT_FREEBSD6

FreeBSD 6 compatibility.

options 	COMPAT_FREEBSD7

FreeBSD 7 compatibility.

options 	COMPAT_FREEBSD9

FreeBSD 9 compatibility.

options 	COMPAT_FREEBSD10

FreeBSD 10 compatibility.

options 	COMPAT_FREEBSD11

FreeBSD 11 compatibility.

options 	COMPAT_FREEBSD12

FreeBSD 12 compatibility.

options 	COMPAT_FREEBSD13

FreeBSD 13 compatibility.

options 	COMPAT_FREEBSD14

FreeBSD 14 compatibility.

options 	SCSI_DELAY=5000

Delay time (in milliseconds) before probing SCSI devices.

options 	KTRACE

ktrace(1) support.

options 	STACK

stack(9) support.

options 	SYSVSHM

SYSV-style shared memory.

options 	SYSVMSG

SYSV-style message queues.

options 	SYSVSEM

SYSV-style semaphores.

options 	_KPOSIX_PRIORITY_SCHEDULING

POSIX P1003_1B real-time extensions.

options 	PRINTF_BUFR_SIZE=128

Prevent interleaving of printf output.

options 	KBD_INSTALL_CDEV

Create character device (CDEV) entries in /dev.

options 	HWPMC_HOOKS

Kernel hooks required by hwpmc(4).

options 	AUDIT

Security event auditing.

options 	CAPABILITY_MODE

Capsicum capability mode.

options 	CAPABILITIES

Capsicum capabilities.

options 	MAC

TrustedBSD MAC framework.

options 	KDTRACE_FRAME

Ensure kernel is compiled with stack frame information.

options 	KDTRACE_HOOKS

Kernel DTrace hooks.

options 	DDB_CTF

Allow kernel ELF linker to load CTF data.

options 	INCLUDE_CONFIG_FILE

Embed this configuration file into the kernel; it can be extracted via config -x or viewed through sysctl kern.conftxt.

options 	RACCT

Resource accounting framework.

options 	RACCT_DEFAULT_TO_DISABLED

Set kern.racct.enable=0 by default.

options 	RCTL

Resource limits framework.

Debugging Support (Always Required)

This subsection introduces options related to debugging support that are always required.

options 	KDB

Enable kernel debugger support.

options 	KDB_TRACE

Print stack trace on panic.

Kernel Dump Functionality

This subsection introduces kernel dump related configuration options.

options 	EKCD

Support for encrypted kernel dumps.

options 	GZIO

Support for gzip-compressed kernel and user dumps.

options 	ZSTDIO

Support for zstd-compressed kernel and user dumps.

options 	DEBUGNET

debugnet network support.

options 	NETDUMP

netdump(4) client support.

options 	NETGDB

netgdb(4) client support.

options 	SMP

Build a kernel with SMP (Symmetric MultiProcessor) support by default.

device		cpufreq

CPU frequency control support.

Bus Support

This subsection introduces options for various bus support.

device		acpi

ACPI support.

device		smbios

smbios, i.e., System Management BIOS, provides basic system management support.

options 	IOMMU

Enable IOMMU.

device		pci

Generic PCI/PCIe bus driver.

options 	PCI_HP

PCIe native hot-plug support.

options 	PCI_IOV

PCI SR-IOV support.

options 	COMPAT_LINUXKPI

Enable Linux Kernel Programming Interface (KPI) compatibility layer.

options 	PPS_SYNC

Enable kernel PLL support for using external PPS signals, monitored by ntpd(8). For more information, see the ntpd documentation: Welcome to the home of the Network Time Protocol (NTP) Project.[EB/OL]. [2026-03-26]. https://www.ntp.org.

device		fdc

Floppy disk drive support. fdc is a legacy ISA bus era driver; floppy disk drives have largely disappeared from modern systems, and this driver is retained only for compatibility with older hardware.

ATA Controllers

This subsection introduces ATA controller related options.

device		ahci

AHCI-compatible SATA controller support.

device		ata

Legacy ATA/SATA controller support. ata(4) is the older subsystem driver with fewer features, and has been superseded by the CAM subsystem-based ahci, mvs, and siis drivers, which support the same hardware and provide more features. ata is only necessary when compatibility with non-AHCI legacy ATA controllers is required.

device		mvs

Marvell 88SX50XX/88SX60XX/88SX70XX and SoC SATA controllers.

device		siis

Silicon Image SiI3124/SiI3132/SiI3531 SATA controllers.

SCSI Controllers

This subsection introduces SCSI controller related options.

device		ahc

AHA2940 and onboard AIC7xxx SCSI devices.

device		ahd

AHA39320/29320 and onboard AIC79xx devices.

device		hptiop

Highpoint RocketRaid 3xxx series.

device		isp

QLogic series controllers.

#device		ispfw

Firmware for QLogic HBAs, typically loaded as a module.

device		mpt

LSI Logic MPT-Fusion controllers.

device		mps

LSI-Logic MPT-Fusion 2.

device		mpr

LSI-Logic MPT-Fusion 3.

device		mpi3mr

Broadcom MPIMR 3.0 IT/IR 24Gb/s SAS Tri-Mode RAID controller.

device		sym

NCR/Symbios Logic SCSI controllers.

device		isci

Intel C600 series SAS controllers.

device		ocs_fc

Emulex Fibre Channel adapters.

device		pvscsi

VMware PVSCSI.

ATA/SCSI Peripherals

This subsection introduces ATA/SCSI peripheral related options.

device		scbus

SCSI bus (required for ATA/SCSI devices).

device		ch

SCSI medium changer.

device		da

Direct access devices (e.g., disks).

device		sa

Sequential access devices (e.g., tapes).

device		cd

Optical discs.

device		pass

Passthrough device (for direct ATA/SCSI access).

device		ses

Enclosure services (SES and SAF-TE protocols).

#device		ctl

CAM target layer.

RAID Controllers Connected via the SCSI Subsystem

This subsection introduces options for RAID controllers connected via the SCSI subsystem.

device		arcmsr

Areca SATA II RAID.

device		ciss

Compaq Smart Array 5*/6* series controllers.

device		ips

IBM (Adaptec) ServeRAID.

device		smartpqi

Microchip smartpqi driver.

device		tws

LSI 3ware 9750 SATA+SAS 6Gb/s RAID controllers.

device		aac

RAID controller, Adaptec FSA RAID series.

device		aacp

SCSI passthrough support for aac (requires CAM).

device		aacraid

Adaptec RAID by PMC.

device		ida

Compaq Smart RAID.

device		mfi

LSI MegaRAID SAS.

device		mlx

Mylex DAC960 series.

device		mrsas

LSI/Avago MegaRAID SAS/SATA, 6Gb/s and 12Gb/s support.

#device		pst

Promise SuperTrak SX6000 RAID controller.

NVM Express (NVMe) Support

This subsection introduces NVM Express (NVMe) related support options.

device		nvme

Base NVMe driver.

device		nvd

Exposes NVMe namespaces as disk devices, depends on nvme.

device 		ufshci			# UFS Host Controller

Universal Flash Storage (UFS) Host Controller Interface support.

device		vmd

Intel Volume Management Device (VMD) support.

device		atkbdc

AT keyboard controller. atkbdc0 controls both the keyboard and PS/2 mouse.

device		atkbd

AT keyboard.

device		psm

PS/2 mouse.

device		kbdmux

Keyboard multiplexer.

device		vga

VGA graphics driver.

device		splash

Boot splash screen and screen saver support.

device		sc

syscons is the traditional console driver, functionally similar to the SCO console. syscons has been superseded by vt(4) as the default console driver and is incompatible with UEFI-booted systems; new deployments are recommended to use vt(4). See: syscons(4)[EB/OL]. [2026-06-10]. https://man.freebsd.org/cgi/man.cgi?query=syscons&sektion=4.

options 	SC_PIXEL_MODE

Add support for rasterized text modes.

device		vt
device		vt_vga
device		vt_efifb
device		vt_vbefb

vt is the default video console driver.

device		agp

Support for various AGP chipsets.

CardBus Bridges

This subsection introduces CardBus bridge related options.

device		cbb

CardBus (Yenta) bridge.

device		cardbus

CardBus (32-bit) bus.

Serial Ports (COM Ports)

This subsection introduces serial port (COM port) related options.

device		uart

Generic UART driver.

Parallel Ports

This subsection introduces parallel port related options.

device		ppc

Parallel port.

device		ppbus

Parallel port bus (required).

device		lpt

Printer.

device		ppi

Parallel port device.

#device		vpo

Requires scbus and da.

device		puc

Multi-I/O card and multi-channel UART support.

device		iflib

PCI/PCI-X/PCIe Ethernet NICs using the iflib infrastructure.

device		em

Intel PRO/1000 series Gigabit Ethernet NICs.

device		igc

Intel I225 series 2.5GbE Ethernet NICs.

device		ix

Intel PRO/10GbE PCIe PF Ethernet.

device		ixv

Intel PRO/10GbE PCIe VF Ethernet.

device		ixl

Intel 700 series Physical Function (PF).

device		iavf

Intel Adaptive Virtual Function (AVF).

device		ice

Intel 800 series Physical Function (PF).

device		vmx

VMware VMXNET3 Ethernet.

device		axp

AMD EPYC integrated NIC (requires miibus support).

PCI Ethernet NICs

This subsection introduces PCI Ethernet NIC related options.

device		bxe

Broadcom NetXtreme II BCM5771X/BCM578XX 10GbE.

device		le

AMD Am7900 LANCE and Am79C9xx PCnet.

device		ti

Alteon Networks Tigon I/II Gigabit Ethernet.

device		mlx5

Base driver.

NVIDIA/Mellanox ConnectX-4 and later models, Ethernet only:

• Depends on COMPAT_LINUXKPI and xz(1)
• mlx5ib depends on ibcore infrastructure, not built-in by default

device		mlxfw

For firmware updates.

device		mlx5en

Ethernet driver.

device		miibus

MII bus support. For PCI Ethernet NICs that use generic MII bus controller code.

Note

Be sure to keep the device miibus line, otherwise the above NICs will not work

device		ae

Attansic/Atheros L2 Fast Ethernet.

device		age

Attansic/Atheros L1 Gigabit Ethernet.

device		alc

Atheros AR8131/AR8132 Ethernet.

device		ale

Atheros AR8121/AR8113/AR8114 Ethernet.

device		bce

Broadcom BCM5706/BCM5708 Gigabit Ethernet.

device		bfe

Broadcom BCM440x 10/100 Ethernet.

device		bge

Broadcom BCM570xx Gigabit Ethernet.

device		cas

Sun Cassini/Cassini+ and NS DP83065 Saturn.

device		dc

DEC/Intel 21143 and various compatible chips.

device		et

Agere ET1310 10/100/Gigabit Ethernet.

device		fxp

Intel EtherExpress PRO/100B (82557, 82558).

device		gem

Sun GEM/Sun ERI/Apple GMAC.

device		jme

JMicron JMC250 Gigabit Ethernet / JMC260 Fast Ethernet.

device		lge

Level 1 LXT1001 Gigabit Ethernet.

device		msk

Marvell/SysKonnect Yukon II Gigabit Ethernet.

device		nfe

NVIDIA nForce MCP onboard Ethernet.

device		nge

NatSemi DP83820 Gigabit Ethernet.

device		re

RealTek 8139C+/8169/8169S/8110S.

device		rl

RealTek 8129/8139.

device		sge

Silicon Integrated Systems SiS190/191.

device		sis

Silicon Integrated Systems SiS 900/SiS 7016.

device		sk

SysKonnect SK-984x & SK-982x Gigabit Ethernet.

device		ste

Sundance ST201 (D-Link DFE-550TX).

device		stge

Sundance/Tamarack TC9021 Gigabit Ethernet.

device		vge

VIA VT612x Gigabit Ethernet.

device		vr

VIA Rhine, Rhine II.

device		xl

3Com 3c90x ("Boomerang", "Cyclone").

Wireless NICs

This subsection introduces wireless NIC related options.

device		wlan

IEEE 802.11 support.

options 	IEEE80211_DEBUG

Enable debugging information.

options 	IEEE80211_SUPPORT_MESH

Enable IEEE 802.11s draft support.

device		wlan_wep

802.11 WEP support.

device		wlan_tkip

802.11 TKIP support.

device		wlan_ccmp

802.11 CCMP support.

device		wlan_gcmp

802.11 GCMP support.

device		wlan_amrr

AMRR transmit rate control algorithm (Adaptive Multi Rate Retry).

device		ath

Atheros CardBus/PCI NICs.

device		ath_hal

Atheros CardBus/PCI chip support.

options 	AH_AR5416_INTERRUPT_MITIGATION

AR5416 interrupt mitigation.

device		ath_rate_sample

SampleRate transmit rate control algorithm for ath.

#device		bwi

Broadcom BCM430x/BCM431x wireless NICs.

#device		bwn

Broadcom BCM43xx wireless NICs.

device		ipw

Intel 2100 wireless NICs.

device		iwi

Intel 2200BG/2225BG/2915ABG wireless NICs.

device		iwn

Intel 4965/1000/5000/6000 wireless NICs.

device		malo

Marvell Libertas wireless NICs.

device		mwl

Marvell 88W8363 802.11n wireless NICs.

device		ral

Ralink Technology RT2500 wireless NICs.

device		wpi

Intel 3945ABG wireless NICs.

Pseudo-Devices

This subsection introduces pseudo-device related options.

device		crypto

Core cryptographic support.

device		aesni

AES-NI OpenCrypto acceleration module.

device		loop

Network loopback interface.

device		padlock_rng

VIA Padlock random number generator.

device		rdrand_rng

Intel Bull Mountain random number generator.

device		ether

Ethernet support.

device		vlan

802.1Q VLAN support.

device		tuntap

Packet tunnel interface.

device		md

Memory "disk."

device		gif

IPv6 and IPv4 tunneling.

device		firmware

Firmware helper module.

device		xz

LZMA decompression support.

device		bpf  # Berkeley Packet Filter

The bpf device enables the Berkeley Packet Filter; when enabled, be mindful of its system administration implications.

Note

DHCP depends on bpf.

USB Support

This subsection introduces USB support related options.

options 	USB_DEBUG

Enable USB debugging information.

device		uhci

UHCI PCI-to-USB interface.

device		ohci

OHCI PCI-to-USB interface.

device		ehci

EHCI PCI-to-USB interface (USB 2.0).

device		xhci

xHCI PCI-to-USB interface (USB 3.0).

device		usb

USB bus (required).

device		usbhid

USB HID transport.

device		hkbd

HID keyboard.

device		ukbd

USB keyboard.

device		umass

Disk / mass storage, requires scbus and da.

Audio Support

This subsection introduces audio support related options.

device		sound

Generic sound card driver (required).

device		snd_cmi

CMedia CMI8338/CMI8738.

device		snd_csa

Crystal Semiconductor CS461x/428x.

device		snd_emu10kx

Creative SoundBlaster Live! and Audigy.

device		snd_es137x

Ensoniq AudioPCI ES137x.

device		snd_hda

Intel High Definition Audio.

device		snd_ich

Intel, NVIDIA, and other ICH AC'97 audio.

VIA VT8233x audio.

MMC/SD

This subsection introduces MMC/SD related options.

MMC/SD bus.

MMC/SD memory cards.

Generic PCI SD host controller.

VirtIO

This subsection introduces VirtIO related options.

Generic VirtIO bus (required).

VirtIO PCI device.

VirtIO Ethernet device.

VirtIO block device.

VirtIO SCSI device.

VirtIO memory balloon device.

Linux KVM Paravirtualization Support

This subsection introduces Linux KVM paravirtualization support related options.

KVM paravirtualized clock driver.

Hyper-V Drivers and Enhanced Support

This subsection introduces Hyper-V driver and enhanced support related options.

Hyper-V driver.

Xen HVM Guest Optimization

This subsection introduces Xen HVM guest optimization related options.

Xen HVM kernel infrastructure.

Note

XENHVM depends on xenpci and xentimer. They must all be present or all absent.

Xen EFI timer device.

Xen HVM hypervisor service driver.

Xen x86 PV timer device.

netmap(4) Support

This subsection introduces netmap(4) support related options.

Netmap provides direct access support for transmit/receive rings of supported NICs.

evdev Interface

This subsection introduces evdev interface related options.

Enable evdev interface support in legacy drivers.

Input event device support.

Install character device (CDEV) /dev/uinput.

HID Support

This subsection introduces HID support related options.

Enable debug message output.

Generic HID support.

Generic HID bus.

Workaround for missing GPIO interrupt support.

EFI Devices

This subsection introduces EFI device related options.

EFI pseudo-device.

EFI real-time clock.