[Wesley W. Terpstra <we...@te...>]

I had a bit more time this weekend, and I managed to unlock my
X710-DA4. It now accepts any SFP+. I tried four different models of
10GBASE-LR transceivers in the card, and they all seemed to work just
fine. Admittedly, I only tested that they could hit 1.1GiB/s TCP flows
for a few minutes before picking one transceiver type and sticking
with it. In particular, I had some A7EL-LND3-ADMA transceivers lying
around that I found for 10EUR a piece and I am now using these
reliably the whole day. In summary, FUD aside, the X710-DA4 works
great with most SFP+s and the decision to lock this card down seems
more like it has something to do with monopolistic practices than
anything else. If I run into any problems with the cheaper SFP+s I
will follow-up with a reply to the list.

The XL710 has four records in NVM that describe whether or not the
card should reject an unknown SFP+. When you flip these four bits, it
will accept any SFP+. I have tested Linux only, but the driver works
unmodified with an unlocked card. Todd Fujinaka mentioned that Intel
sells an unlocked optics card, so I imagine the drivers were tested
against those cards which is why it works under linux. Therefore, I'd
wager the windows driver likewise works with an unlocked card, though
I have not tested it.

Be warned: running nvmupdate64e -rd will restore the lock bits! Normal
update appears to preserve their value.

To unlock your card, you will need linux 4.5, skill with Cl, and some
time. I have not prepared a general-purpose unlocking tool, because
the NVM format might differ between cards and thus this procedure
should only be undertaken by someone who knows what they are doing.

Step one is to find the "PHY Capability LAN 0" structure in the NVM.
The NVM image that nvmupdate64e v1.26.17.09 writes seems to have a
corrupt "PHY Capability LAN 0 Pointer", so you will need to find the
record by hand. Use the attached my-tool.c to read the NVM. You will
need to set devid to the PCI express device ID for your card. lspci on
my machine showed:

My "PHY Capability LAN 0" record looked like this:

00006870 + 00 => 000b
00006870 + 01 => 0022 = external SFP+
00006870 + 02 => 0083 = int: SFI, 1000BASE-KX, SGMII (???)
00006870 + 03 => 1871 = ext: 0x70 = 10GBASE-{SFP+,LR,SR} 0x1801=crap?
00006870 + 04 => 0000
00006870 + 05 => 0000
00006870 + 06 => 3303 = SFP+ copper (passive, active), 10GBase-{SR,LR}, SFP
00006870 + 07 => 000b
00006870 + 08 => 2b0c
*** The important register ***
(0xb=bits 3+1+0 = enable qualification (3), pause TX+RX capable (1+0),
0xc = 3+2 = 10GbE + 1GbE)
00006870 + 09 => 0a00
00006870 + 0a => 0a1e = default LESM values
00006870 + 0b => 0003

I had 3 more records just like this at offsets 0x687c, 0x6888, and
0x6894. The key field is at offset 0x08 (PHY Capabilities Misc0). You
need to clear bit 11. In my case that meant writing 0x230c.