---
name: "gcu"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["openbsd"]
url: "https://new.carta.tech/gcu"
---

# gcu(4)

Intel EP80579 Global Configuration Unit

## NAME

**gcu** – Intel EP80579 Global Configuration Unit

## SYNOPSIS

**gcu\* at pci?**

## DESCRIPTION

The **gcu** driver provides access to the miibus that is hidden behind the GCU device. It is used to control PHYs on embedded designs utilizing Intel's EP80579 chips.

The GCU also provides access to CAN, SSP and TDM signal strength drivers, but since they are not supported by OpenBSD the driver does not provide any functionality related to them.

## SEE ALSO

[em(4)](/em/4.md), [intro(4)](/intro/4.md), [netintro(4)](/netintro/4.md), [pci(4)](/pci/4.md)

Intel's EP80579 Datasheet: **http://download.intel.com/design/intarch/ep80579/320066.pdf**

## HISTORY

The **gcu** driver first appeared in OpenBSD 4.7.

## AUTHORS

The **gcu** driver was written by Dariusz Swiderski ⟨*dms@openbsd.org*⟩, partially based on the FreeBSD driver released by Intel under the ISC license.