Some RealTek chip are not able to negociate at 2.5Gb

Framework Desktop
1

I have 2 Framework Desktops and one is not able to correctly negociate at 2.5Gb/s: Same switch, same port on the switch, same cable.

Reproduced on Ubuntu Linux and on FreeBSD.

The difference between them is very subtle:

Both chips report identical device=0x8126, subvendor=0xf111, subdevice=0x000a, and PCI rev=0x01, but they are not because they have a different XID detected by the drivers (that load different firmware on each):

  • 0x64a , known as “rev.b” (VER_66), uses firmware rtl8126a-3.fw and fails to negociate at 2.5Gb/s.
  • 0x649 , known as orig 8126A (VER_65), uses firmware rtl8126a-2.fw and succeed to negociate at 2.5Gb/s

Does anyone meet the same problem ? (sudo dmesg | grep -i r8169 | grep XID to get which XID you are able to negociate at 2.5Gbs)

2

Only time I have seen speed negotiated wrong is because of a bad cable.

3

full cross-tests were done here (switch port and cable).