crossbow discuss - Jan 2009 - questions on crossbow ring capabilities

Hi,

I maintain a gldv3 driver for a 10GbE. I am trying to make it support network
virtualization.

Though this 10GbE hardware  does support multiple TX/RX rings, multiple MAC
addresses & VLAN tags and PCI-X interrupt, it has very limited rx packet
steering capabilities: only based on VLAN tag match, MAC address match,
multicast address match, RSS match. When such a (VLAN tag, MAC addr etc) match
happens, the packet is steered to a predefined ring, all other packets go to
default ring. It does not check IP addresses, protocols and ports.

So, for this hardware, how do I expose its ring capabilites? Is the NIC Level 1
VIRT capable only, not Level 2?

I am still very confused on Rx ring groups. What is the criteria to group rings?
Does the hardware must support ring group? Do I need ring group for this 10GbE?

Tom
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Tom,

On Jan 26, 2009, at 10:05 AM, Tom Chen wrote:
> Hi,
>
> I maintain a gldv3 driver for a 10GbE. I am trying to make it  
> support network virtualization.
>
> Though this 10GbE hardware  does support multiple TX/RX rings,  
> multiple MAC addresses & VLAN tags and PCI-X interrupt, it has very  
> limited rx packet steering capabilities: only based on VLAN tag  
> match, MAC address match, multicast address match, RSS match. When  
> such a (VLAN tag, MAC addr etc) match happens, the packet is steered  
> to a predefined ring, all other packets go to default ring. It does  
> not check IP addresses, protocols and ports.
>
> So, for this hardware, how do I expose its ring capabilites? Is the  
> NIC Level 1 VIRT capable only, not Level 2?
 From your description it seems your device maps to MAC_VIRT_LEVEL1.  
Traffic is demultiplexed to multiple groups depending on L2 MAC  
addresses, and one or more MAC addresses can be assigned to each  
group. The MAC layer will invoke the addmac/remmac entry points of the  
driver to associate MAC addresses with groups.

Within each group, the device can then have one or more hardware  
rings. If the hardware has multiple rings per group, then the hardware  
is expected to fanout the traffic to the rings of a group (RSS).

Currently our interface doesn''t allow VLAN tags to be directly  
associated with hardware groups, so we do VLAN demultiplexing in  
software in mac. Enabling VLAN hardware classification is on the list  
of improvements that we want to make to the driver API.

Nicolas.

PS: BTW keep in mind that the GLDv3 driver API is still not a  
committed interface, and we may still make incompatible changes to the  
API until we make it a committed interface.
>
>
> I am still very confused on Rx ring groups. What is the criteria to  
> group rings? Does the hardware must support ring group? Do I need  
> ring group for this 10GbE?
>
> Tom
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> This message posted from opensolaris.org
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> crossbow-discuss at opensolaris.org
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-- 
Nicolas Droux - Solaris Kernel Networking - Sun Microsystems, Inc.
droux at sun.com - http://blogs.sun.com/droux

Tom,

Based on what you describe, you should use Level 1 VIRT. Basically we can 
create H/W Rx rings based VNICs with a MAC address or VLAN tag.

The Rx ring group is used when you assign all Rx rings (more than one)
to the same MAC address and the NIC can spread traffic within the
assigned rings based on some hashing scheme. If not, then we can
use only one Rx ring per VNIC or for primary NIC and you can
advertize multiple groups with 1 Rx ring each (static).

Cheers,
Sunay
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