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BWI(4) Device Drivers Manual BWI(4)

bwiBroadcom AirForce IEEE 802.11b/g wireless network device

bwi* at cardbus?
bwi* at pci?

The bwi driver provides support for Broadcom AirForce based PCI/Cardbus network adapters.

These are the modes the bwi driver can operate in:

BSS mode
Also known as mode, this is used when associating with an access point, through which all traffic passes. This mode is the default.
monitor mode
In this mode the driver is able to receive packets without associating with an access point. This disables the internal receive filter and enables the card to capture packets from networks which it wouldn't normally have access to, or to scan for access points.

The bwi driver can be configured to use Wired Equivalent Privacy (WEP) or Wi-Fi Protected Access (WPA1 and WPA2). WPA2 is the current encryption standard for wireless networks. It is strongly recommended that neither WEP nor WPA1 are used as the sole mechanism to secure wireless communication, due to serious weaknesses. WPA1 is disabled by default and may be enabled using the option "wpaprotos wpa1,wpa2". For standard WPA networks which use pre-shared keys (PSK), keys are configured using the "wpakey" option. WPA-Enterprise networks require use of the wpa_supplicant package. The bwi driver relies on the software 802.11 stack for both encryption and decryption of data frames.

The transmit speed is user-selectable or can be adapted automatically by the driver depending on the received signal strength and on the number of hardware transmission retries.

The bwi driver can be configured at runtime with ifconfig(8) or on boot with hostname.if(5).

The driver needs a firmware file which is loaded when an interface is brought up:


A prepackaged version of the firmware can be installed using fw_update(8).

The following cards are among those supported by the bwi driver:

Apple Airport Extreme BCM4306 PCI b/g
Apple Airport Extreme BCM4318 PCI b/g
ASUS WL-138g BCM4318 PCI b/g
Buffalo WLI-CB-G54 BCM4306 CardBus b/g
Compaq R4035 onboard BCM4306 PCI b/g
HP nx6125 BCM4319 PCI b/g
Linksys WPC54G Ver 3 BCM4318 CardBus b/g
Linksys WPC54GS Ver 2 BCM4318 CardBus b/g
TRENDnet TEW-401PCplus BCM4306 CardBus b/g
US Robotics 5411 BCM4318 CardBus b/g

The following example scans for available networks:

# ifconfig bwi0 scan

The following hostname.if(5) example configures bwi0 to join network “mynwid”, using WPA key “mywpakey”, obtaining an IP address using DHCP:

join mynwid wpakey mywpakey
inet autoconf

arp(4), cardbus(4), ifmedia(4), intro(4), netintro(4), pci(4), hostname.if(5), ifconfig(8)

The bwi driver first appeared in OpenBSD 4.3.

The bwi driver was written for DragonFly by Sepherosa Ziehau and ported to OpenBSD by Jonathan Gray and Marcus Glocker.

Some chips are incorrectly calibrated due to the lack of documentation, which can slow the amount of traffic to the point of being unusable. Furthermore this driver only supports firmware version 3.

The BCM4331 chip isn't supported by this driver but the driver disables the chip if detected, since some buggy EFI revisions found in 2011-2012 Macs leave the chip enabled, causing it to emit spurious interrupts when the shared interrupt line is enabled.

This driver does not support powersave mode.

January 5, 2022 OpenBSD-current