I found a pair of these dual-port 10GbE NICs for $25, and had no idea what to expect.

The good:

• Excellent secondhand value
• Supports SR-IOV, VM switching, and the other usual stuff
• No SFP lock
• Can be cross-flashed
• Appears to use the same driver (be2net) for both PFs and VFs, unlike Intel cards which have a separate VF driver

The bad:

• There’s a known issue with these where you have to do trickery to bring the ports back up after a power cycle. It doesn’t seem to be OS/driver-specific, because even the BIOS shows “Link Down”. This is the deal breaker. On Linux, you can do it with ethtool -t but on Windows it requires a proprietary program.
• SR-IOV support is toggled on and off in the BIOS. However, the IBM firmware doesn’t seem to expose this. I had to use an HPE or Lenovo image instead.
• Would it kill Broadcom to just let you download the firmware from them, rather than having to peruse every 3rd party vendor site to figure out who has the latest firmware?
• The card is x8 but seems to have some extra pins on the end of the PCIe connector. It seems to work fine in a x16 slot, but does not physically fit in a closed-ended x8 slot.

In short: they’re cheap for a reason. Don’t buy them.

Notes:

You may have to flash twice if the card is running older firmware. There’s also this oddity where the interface has to be up (ip link set up, not physically plugged in) in order to flash – you’d think it would be the other way around.