Ethernet doesn't work correctly on Asus M3A78-T in modern versions of the Linux kernel (at least v5.4 and newer); worked on kernel v4.4

I don’t remember the details so, if I revisit this issue, I’ll be sure to provide specifics.

But basically, for years, I had Linux Mint 18.1 on it (kernel v4.4) and everything “just worked”. I think Mint 18.3 also worked (which wouldn’t be a surprise due to it using the same v4.4 kernel), but I had no reason to upgrade it because it was just running as a very basic seed box and file server due to the hardware being a very ideal combination for such a task.

However, I definitely know that the ethernet straight-up doesn’t work correctly on newer versions of the Linux kernel, such as v5.4 as is provided with Linux Mint 20 and kernel v5.15 as is provided with Linux Mint 21. There’s a setting in the BIOS you can enable that will make ethernet kind of work, but it also forces your CPU to run as single core, and the ethernet will go MIA and not come back until after reboot if you use S3 suspend “sleep mode”.

I recall reading something that Marvell at some point stopped maintaining kernel support for their older-ish network chips, and the M3A78-T does in fact use a Marvell 88E8056 gigabit ethernet controller.

For reference, this motherboard was, like several other AMD-chipset Asus-branded pre-AM3+ motherboards, were ideal for certain low-power passively-cooled home server applications due to the following combination:

  • unbuffered ECC
  • 4 RAM slots (albeit DDR2, but 8GB worked well)
  • integrated graphics
  • underclocking and undervolting support

And it’s not been until recently with second-hand Pro-SKU AM4 G-series processors for cheap on ebay that you’ve been able to get all four of those features on consumer motherboards once again.

(fun fact: this motherboard was originally the one used by the family friend mentioned in my “M550 permanently locked to read-only” thread, but I thankfully swapped it for an Asus M3N78 Pro (Nvidia chipset AM2+ board) that lacked ECC and obviously used and Nvidia iGPU instead which made no difference to the family friend’s Windows OS but very much did so for my basic Linux server use-case, therefore that Nvidia board ended up being the one that got possibly damaged in the power surge rather than this M3A78-T)