Compaq Tru64 UNIX Installation Manual page 91

Writing network device drivers
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Sets the if_start member of the ifnet data structure for this device
3
to el_start, which is the if_el device driver's start transmit for
output interface.
Sets the if_output member of the ifnet data structure for this
4
device to ether_output, which is the if_el device driver's output
interface. Tru64 UNIX provides this kernel routine. All network device
drivers, including Token Ring and FDDI drivers, must set if_output
to ether_output, rather than implementing a driver-specific output
interface.
An mb( ) (memory barrier) preceeds the setting of the if_output
member. Members of the ifnet structure must be initialized in the
order shown. The mb( ) ensures that all other function pointers are set
before the if_output function pointer is set. This order is necessary
because the if_el device can be unattached and later attached again.
Sets the if_flags member of the ifnet data structure for this device
5
to the bitwise inclusive OR of the following status bits that are defined
in the if.h file:
IFF_BROADCAST
IFF_MULTICAST
IFF_NOTRAILERS
IFF_SIMPLEX
An mb( ) (memory barrier) precedes the setting of the if_flags
member. All the function pointers must be initialized before the
if_flags field is set, in case the if_el device has been unattached
and then attached again.
Sets the if_timer member of the ifnet data structure for this device
6
to the value 0 (zero). This is the number of seconds to wait until the
driver's watchdog interface is called. Setting the if_timer member to
0 (zero) disables the timer.
Sets the if_sysid_type member of the ifnet data structure for
7
this device to the value 0 (zero). This optional member specifies a
unique number that identifies the bus adapter hardware to the network
management software. This unique number is referred to as the MOP
system ID device code.
Implementing the Autoconfiguration Support Section (attach) 6–7
Signifies that the network interface supports
broadcasting and that the associated broadcast
address is valid.
Signifies that the network interface supports multicast.
Signifies that the transmission avoids the use of
trailers. The term trailers refers to the IP trailer
encapsulation protocol, which is obsolete.
Signifies that the interface cannot identify
its own transmissions.

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