GEM(4) | Device Drivers Manual | GEM(4)

# NAME

`gem` —
ERI/GEM/GMAC Ethernet device driver

# SYNOPSIS

`gem* at pci? dev ? function ?`
`gem* at sbus? slot ? offset ?`

Configuration of PHYs may also be necessary. See mii(4).

# DESCRIPTION

The `gem` driver provides support for the GMac Ethernet hardware found mostly in the last Apple PowerBooks G3s and most G4-based Apple hardware, as well as many Sun UltraSPARCs.

Cards supported by this driver include:

- Sun GEM Gigabit Ethernet (SX fibre variants)
- Sun ERI 10/100
- Apple GMAC

The GEM family supports hardware checksumming to assist in computing IPv4 TCP checksums. The `gem` driver supports this feature of the chip. See ifconfig(8) for information on how to enable this feature.

# SEE ALSO

bmtphy(4), ifmedia(4), intro(4), makphy(4), mii(4), ifconfig(8)

Sun Microsystems, GEM Gigabit Ethernet ASIC Specification, http://www.sun.com/processors/manuals/ge.pdf.

Sun Microsystems, Sbus GEM Specification, http://mediacast.sun.com/users/Barton808/media/gem_sbus-1.pdf.

# HISTORY

The `gem` device driver appeared in NetBSD 1.6. Support for PCI SX fibre cards was added in NetBSD 5.0. Support for SBus SX fibre cards was added in NetBSD 5.0.

# AUTHORS

The `gem` driver was written by Eduardo Horvath ⟨eeh@NetBSD.org⟩. SX fibre support was added by Julian Coleman ⟨jdc@NetBSD.org⟩. The man page was written by Thomas Klausner ⟨wiz@NetBSD.org⟩.

# BUGS

The hardware checksumming support does not support IPv4 UDP, although this was allowed prior to NetBSD 5.0. Also, the hardware IPv4 TCP receive checksumming support has bugs, so this is disabled.

On the SX fibre variants of the hardware, the link will stay down if there is a duplex mismatch. Also, packet transmission may fail when in `half-duplex` mode.

June 2, 2018 | NetBSD 9.2