GEM(4)                  NetBSD Kernel Interfaces 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:
           o   Sun GEM gigabit ethernet (SX fibre variants)
           o   Sun ERI 10/100
           o   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), 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 4.1.  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.

NetBSD 5.0_STABLE             September 15, 2008             NetBSD 5.0_STABLE
