SR(4)                   /i386 Kernel Interfaces Manual                   SR(4)

     sr — synchronous RISCom/N2 / WANic 400/405 device driver

     device sr

     For ISA cards, in /boot/device.hints:"isa""0x300""10""0xd0000""0x0"

     device sppp

     The sr driver supports the RISCom/N2 ISA cards, N2pci and the WANic
     400/405 PCI cards that are based on the HD64570 chip.

     If you have ISA cards, you need to specify the resources for them in
     /boot/device.hints.  If you have the second ISA card, add


     The standard FreeBSD sppp code is used for the link level layer.  The
     default protocol used is PPP.  The Cisco HDLC protocol can be used by
     adding link2 to ifconfig(8).

     Alternately, the driver can be compiled to support netgraph(4) (see

     The flags specification in /boot/device.hints is optional.  If it is not
     specified, the driver will assume the following:

           The card has 2 ports.

           The clock for the serial ports is external and the transmitter uses
                   the same clock as the receiver.

     The flags are a bit field and can be used to force a different behaviour
     than the default.

           0x01    The card has only one port.

           0x10    Use separate external clocks for transmit and receive on
                   port 0.

           0x40    Use separate external clocks for transmit and receive on
                   port 1.

     The card only supports IRQ 3, 4, 5, 7, 10, 11, 12 and 15.

     The iomem area is a 16Kb block and must start at a 16Kb boundary.

     The sr driver supports the following hardware:

     ·   SDL Communications RISCom/N2 ISA
     ·   SDL Communications N2pci
     ·   SDL Communications WANic 400/405 PCI

     If the kernel is compiled with options NETGRAPH then the sppp and Cisco
     HDLC modes are disabled (and the sppp driver is unneeded), and this
     driver functions as a netgraph(4) node with a single hook named rawdata.
     Connecting to this hook enables the transmission of raw HDLC frames.  The
     node will have the same name as the device with ``sync_'' prepended,
     e.g., sync_sr0.

     sr%d: Warning illegal interrupt %d.  The card cannot use the specified
     interrupt.  Choose a different one.

     ar(4), cx(4), netgraph(4), netintro(4), ifconfig(8)

     The sr device driver was written by John Hay <>.

     Netgraph support was added by Julian Elischer <>.

     At the moment only the X.21 interface is tested.  The others may need
     tweaks to the clock selection code.

     The code can probably stand some optimizing.

                                March 18, 2005