[openib-general] ip_ib_mc_map?

[Or Gerlitz]

Steve Wise wrote:
> where can I find this symbol?  I can't load rdma_cm on rhel4u4...
> rdma_cm: Unknown symbol ip_ib_mc_map

Sean, OK, sorry not to mention the rh4u4 issue once you did the push to 
OFED 1.2 ...

 From a reason that no one at RH can trace... someone went and removed 
all the support for ARPHRD_INFINIBAND multicast from u4 where it exists 
perfectly fine in u3 and hopefully on u5 as well (Doug can you update?), 
see https://bugs.openfabrics.org/show_bug.cgi?id=2661

Specifically, the below snip from the patch means that on rh4 u4 all 
IPv4 ARPHRD_INFINIBAND multicast goes on the broadcast group !!!

> Index: linux-2.6.9/net/ipv4/arp.c
> ===================================================================
> --- linux-2.6.9.orig/net/ipv4/arp.c	2004-10-18 23:55:06.000000000 +0200
> +++ linux-2.6.9/net/ipv4/arp.c	2006-09-20 14:43:59.000000000 +0300
> @@ -213,6 +213,9 @@
>  	case ARPHRD_IEEE802_TR:
>  		ip_tr_mc_map(addr, haddr);
>  		return 0;
> +	case ARPHRD_INFINIBAND:
> +		ip_ib_mc_map(addr, haddr);
> +		return 0;
>  	default:
>  		if (dir) {
>  			memcpy(haddr, dev->broadcast, dev->addr_len);

anyway, OFED wise, i see two ways to solve this:

1) adding a backport to the rdma_cm containing ip_ib_mc_map, period.

This means that apps offloading multicast traffic through the rdma cm 
would use the correct group where apps working through the net stack
use the broadcast group.

2) having the rdma cm follow the net stack and make its consumer use the 
broadcast group.

Or.