Drivers on FreeBSD

Last update: 10.04.2021

By default, FreeBSD does not load all possible drivers; it must be instructed to load the drivers specific to our hardware.

For example, for a list of unloaded drivers, we can use the following command:

root #: dmesg | grep "no driver attached"
root #: dmesg | grep "no driver attached"

pci12: <network> at device 0.0 (no driver attached)
pci0: <multimedia, HDA> at device 27.0 (no driver attached)
pci0: <serial bus, SMBus> at device 31.3 (no driver attached)
pci9: <base peripheral, SD host controller> at device 0.1 (no driver attached)
pci9: <mass storage> at device 0.2 (no driver attached)

What stands out here: an audio chip (multimedia HDA), a network card, the WLAN in my case (network), an SMBus chipset (serial bus, SMBus) and an SD card reader.

Loading the driver of the SD card reader

root #: sysrc kld_list + = "mmc mmcsd sdhci"


The most common audio drivers have been enabled by default since 9.0. If it doesn't, we load a "meta" driver that loads all of the audio drivers, and then we look at the one that is accepted:

root #: kldload snd_driver
root #: cat /dev/sndstat

FreeBSD Audio Driver (newpcm: 64bit 2007061600 / amd64)

Installed devices:
pcm0: <Intel 82801H High Definition Audio Controller> at memory 0xf6dfc000 irq 21 kld snd_hda [20080420_0052] [MPSAFE] (1p: 1v / 1r: 1v channels duplex default)

In this case, the snd_hda drivers match. This driver has been included as standard in the generic kernel since version 9.0, but for an older version, loading must be declared using the old method:

root #: sysrc kld_list + = "snd_hda"

Or, since 9.0, adding its name to the kld_list variable in the /etc/rc.conf file.


To use the loudspeakers / Bluetooth headsets, these must be transferred via the virtual_oss package. We can install the whole thing with the following command:

root #: pkg install virtual_oss virtual_oss_ctl


We load and check whether the driver was loaded correctly:

[root @ laptop] ~ #: kldload ichsmb
[root @ laptop] ~ #: dmesg | grep smbus
smbus0: <System Management Bus> on ichsmb0

We add this module to the list of modules to be loaded automatically:

root #: sysrc kld_list + = "smbus"

ACPI-specific instructions

Very useful on laptops, there are ACPI modules that are manufacturer-specific. Here is the list of modules available on FreeBSD 11:

Module name description
acpi_asus.ko Asus laptop extras
acpi_dock.ko Laptop docking station device driver
acpi_fujitsu.ko Fujitsu laptop extras
acpi_hp.ko ACPI extras driver for HP laptops
acpi_ibm.ko ACPI extras driver for IBM laptops
acpi_panasonic.ko ACPI hotkey driver for Panasonic laptops
acpi_sony.ko ACPI notebook controller driver for Sony laptops
acpi_toshiba.ko Toshiba HCI interface
acpi_video.ko ACPI Video Extensions driver
acpi_wmi.ko ACPI to WMI mapping driver (loaded by others if necessary)

To add the variable kld_load based on our hardware. For example, for my IBM laptop I have: acpi_ibm and acpi_video.

Power saving mode

This saves the battery:

root #: echo "hw.pci.do_power_nodriver = 3" >> /etc/sysctl.conf
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