gldm_set_multicast() Entry Point

int prefix_set_multicast(gld_mac_info_t * macinfo, 
     unsigned char * multicastaddr, int multiflag);

gldm_set_multicast() enables and disables device-level reception of specific multicast addresses. If the third argument multiflag is set to GLD_MULTI_ENABLE, then the function sets the interface to receive packets with the multicast address pointed to by the second argument. If multiflag is set to GLD_MULTI_DISABLE, the driver is allowed to disable reception of the specified multicast address.

This function is called whenever GLD wants to enable or disable reception of a multicast, group, or functional address. GLD makes no assumptions about how the device does multicast support and calls this function to enable or disable a specific multicast address. Some devices might use a hash algorithm and a bitmask to enable collections of multicast addresses; this procedure is allowed, and GLD filters out any superfluous packets. If disabling an address could result in disabling more than one address at the device level, the device driver should keep whatever information it needs in order to avoid disabling an address that GLD has enabled but not disabled.

gldm_set_multicast() will not be called to enable a particular multicast address that is already enabled, nor will it be called to disable an address that is not currently enabled. GLD keeps track of multiple requests for the same multicast address and only calls the driver's entry point when the first request to enable, or the last request to disable, a particular multicast address is made. If sufficient resources are currently not available to carry out the request, the function should return GLD_NORESOURCES. The function should return GLD_NOTSUPPORTED if the requested function is not supported.