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
Thegem 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.