[ipxe-devel] Infiniband GUID

Allen, Benjamin S. bsallen at alcf.anl.gov
Wed Sep 6 00:08:19 UTC 2017

> On Sep 5, 2017, at 6:57 PM, Michael Brown <mcb30 at ipxe.org> wrote:
> On 06/09/17 00:38, Allen, Benjamin S. wrote:
>> I'm attempting to emulate what we're doing for ethernet clients in ISC-DHCP by passing the iPXE cfg path, eg 'filename "${mac}";', where iPXE helpfully evaluates and fills in ${mac}.
> The (local) eIPoIB MAC address is systematically derived from the GUID by just omitting the middle two bytes:
>  http://git.ipxe.org/ipxe.git/blob/HEAD:/src/drivers/net/ipoib.c#l273
> If you know the GUID, then you can trivially calculate the IPoIB MAC that will be used by iPXE (and exposed as ${netX/mac}).  Does this give you the functionality that you need?
> Michael

Yes this is pretty reasonable workaround, and is a pretty trivial change to make in our codebase. I do wonder on large IB fabrics if the removal of the middle bytes will cause any collisions.



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