[ipxe-devel] Intel 82576 MAC swapping

[Kieran Evans]

The Intel pxe from agrees with Linux on the addresses I.e. the inverse of
what iPXE thinks. Port 0 is 0c port 1 is 0d.

/Kieran
On Aug 7, 2012 2:27 AM, "Michael Brown" <mbrown at fensystems.co.uk> wrote:

> On Friday 27 Jul 2012 13:48:54 Kieran Evans wrote:
> > I'm working on these servers via the remote management controllers,
> > they're about 50 miles away from me at the moment, so to make it easier,
> > I ran ethtool -e eth1/eth3 from Ubuntu to dump the EEPROM.
> >
> > http://dbyz.co.uk/eth1.dmp
> > http://dbyz.co.uk/eth3.dmp
> >
> > It should be the same as iPXE would output (as it's being read directly
> > from the HW).
>
> Thanks.  The curious thing is that the MAC address as stored in the EEPROM
> is
> 00:26:6c:fc:e4:0d, i.e. bit 0 is set.
>
> The MAC addresses determined by iPXE are correct as far as I can tell:
>
>   LAN 0 (02:00.0) uses the address as stored in the EEPROM:
> 00:26:6c:fc:e4:0d
>   LAN 1 (02:00.1) uses this address XORed with 01: 00:26:6c:fc:e4:0c
>
> This is as described by the documentation, as far as I can tell.
>
> Usually, with a dual-port NIC, bit 0 of the address stored in the EEPROM
> will
> be clear.  I would expect to see 00:26:6c:fc:e4:0c stored in the EEPROM,
> which
> would give
>
>   LAN 0 : 00:26:6c:fc:e4:0c
>   LAN 1 : 00:26:6c:fc:e4:0d
>
> I'm also puzzled why Linux ends up choosing different MAC addresses than
> iPXE.
>
> Does iPXE's choice of MAC address agree with the choice made by the Intel
> PXE
> ROM?  If you boot from port 0, what MAC address is displayed by the Intel
> PXE
> base code, and what MAC address is then displayed for the same port by
> iPXE?
>
> Michael
>
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