---
name: "if_en"
section: "4"
platform: "linux"
package: "freebsd-manpages"
version: "6.0-5"
release: "Debian 4.0 (Etch)"
platforms: ["linux"]
url: "https://new.carta.tech/if_en"
---

# if\_en(4)

device driver for Midway-based ATM interfaces

## NAME

**en** – device driver for Midway-based ATM interfaces

## SYNOPSIS

To compile support for the

**en** driver into your kernel, place the following lines in your kernel configuration file:

**device en** **device atm** **device utopia**

Alternatively, to load the

**en** driver at boot time, place the following liness in [loader.conf(5)](/loader.conf/5.md):

```
if_en_load="YES"
```

## DESCRIPTION

The **en** device driver supports Midway-based ATM interfaces including the Efficient Networks, Inc. ENI-155 and Adaptec ANA-59x0. Midway is an AAL5 SAR (Segmentation and Reassembly) chip.

For configuring the card for IP see [natmip(4)](/natmip/4.md).

The following sysctls are recognized by the driver additionally to those handled by [utopia(4)](/utopia/4.md):

- *hw.atm.enX.istats*

  Contains an array of *uint32\_t* with internal driver statistics.

- *hw.atm.enX.debug*

  This is a bit map of debugging options. This variable is only available when the driver is compiled with debugging support.

The driver supports the media options **sdh**, **noscramb** and **unassigned** (see [utopia(4)](/utopia/4.md)).

## DIAGNOSTICS

```
en0 <Efficient Networks ENI-155p> rev 0 int a irq 5 on pci0:16
en0: ATM midway v0, board IDs 6.0, Utopia (pipelined), 512KB on-board RAM
en0: maximum DMA burst length = 64 bytes
en0: 7 32KB receive buffers, 8 32KB transmit buffers allocated
```

## CAVEATS

The driver extensively uses DMA on PCI. The first generation PCI chipsets do not work or exhibit poor performance.

## SEE ALSO

[natm(4)](/natm/4.md), [natmip(4)](/natmip/4.md), [utopia(4)](/utopia/4.md), [ifconfig(8)](/ifconfig/8.md), [route(8)](/route/8.md)

## AUTHORS

Chuck Cranor of Washington University implemented **en** driver in 1996 for NetBSD.