[openib-general] Re: rdma_bind_addr question

[Steve Wise]

I think we can simplify this without changing the format of how the IPoIB 
mac addr is stored.

assume the IPoIB netdevs have type ARPHRD_INFINIBAND, and iWARP netdevs are 
type ARPHRD_ETHERNET.

The CMA would search only the IWARP openib devices and compare the 6 byte 
MAC address if the netdev type is ETHERNET, and search only the IB openib 
devices matching on the full 20 byte IPoIB mac addr.  Doing this removes the 
possibility that a 6 byte ethernet mac addr accidentally matches the first 6 
bytes of the IPoIB mac addr...

Steve.



----- Original Message ----- 
From: "Tom Tucker" <tom at ipperformance.com>
To: "Sean Hefty" <mshefty at ichips.intel.com>
Cc: <openib-general at openib.org>
Sent: Thursday, October 20, 2005 11:41 PM
Subject: [openib-general] Re: rdma_bind_addr question


> On Thu, 2005-10-20 at 13:09 -0700, Sean Hefty wrote:
>> Tom Tucker wrote:
>> > BTW -- I think this means that we need an ARPHRD_IWARP type.
>>
>> It may be that the CMA can simply look in its local device list for an 
>> ib_device
>> that has a given MAC address.
>
> After pondering this, I think you're correct. There is one issue,
> however. Currently, the GID is stored beginning at the fourth byte of
> the dev_addr for IBoIB, but the Ethernet MAC address begins at byte 0.
> Is it possible to move this 4B quantity to follow the GID? If so, we
> could pad the dev_addr for iWARP devices with zeroes and use the exact
> same code to search the cma device table. If the device is found, it
> already has a type in the ib_device structure to distinguish between IB
> and iWARP devices.
>
> If the caller gave us an IP address for a dumb Ethernet device, we would
> go looking for it in the cma device list and simply not find it. It
> would still fail, just later, and would avoid a new ARPHRD type.
>
>>
>> I don't know the detail of how iWarp will work with this.  Will iWarp 
>> need a
>> call similar to ib_translate_addr() to translate an IP address into a MAC
>> address?  Are the MAC addresses stored with the ib_device somehow?
>>
>> - Sean
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