[ipxe-devel] Intel X520 with 1GbE SFPs

Florian Rinke git+ipxe at florianrinke.de
Tue Aug 14 16:22:24 UTC 2018

Hello iPXE folks,

as discussed with Michael on irc I'm sending you my results from
debugging connectivity issues with 1GbE-SFPs connected to an Intel 82599

Symptoms were "Link not coming up" without any error messages, digging
through source code and datasheet showed that initialization currently
assumes default values for AUTOC register to be sufficient - which it is
not for GBit SFPs. I found two working scenarios, which I've attached:

0001a) Set "Link mode select" for 1GbE, causes link to come up
instantly, but would probably prevent 10GbE connections

0001b) Set "Link mode select" to have autodiscovery include 1GbE links.
This allows links to come up, should also work for 10G links, but has a
heavy delay (I measured random times between 10 and 50 seconds...).

Additionally, I stumbled upon an issue with CRC stripping (see patch
0002). Currently bit 0 in RDRXCTL is set for enabling HW CRC stripping,
but according to the datasheet (Rev. 3.3, March 2016) it should be bit
1. Unfortunately, bit 0 is simply missing in the relevant table (also in
older versions I found from 2012 and 2009).

Unfortunately I have no means of testing the variants on different
hardware, especially with 10GbE-connections. Probably it would be better
to actively try different link options; is something like this already
implemented somewhere else in iPXE?

Best regards,

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