[coreboot] Coreboot ECC support in Asrock IMB-A180-H

[Kyösti Mälkki]

On Sun, Sep 10, 2017 at 1:53 PM, Alberto Bursi <alberto.bursi at outlook.it> wrote:
>
>
> On 09/07/2017 01:24 PM, Kyösti Mälkki wrote:
>> On Thu, Sep 7, 2017 at 1:40 PM, Nico Huber <nico.h at gmx.de> wrote:
>>> Hello Alberto,
>>>
>>>   On 09/06/2017 09:30 PM, Alberto Bursi wrote:
>>>> I've stumbled upon a Asrock IMB-A180-H board (a eKabini-based
>>>> "industrial" mini-itx motherboard) on ebay and since it is supported by
>>>> Coreboot I was considering about purchasing it.
>>>>
>>>> The APU onboard supports ECC ram (ECC so-dimms are kinda rare but I can
>>>> find them), while of course the Asrock site does not say anything about
>>>> ECC support (how unexpected).
>>> it's rather unlikely that a board supports it when the manufacturer
>>> doesn't mention it. ECC support needs additional traces on the main-
>>> board (as the bus is 72 bits wide instead of 64 bits). So just having
>>> compatible chips doesn't suffice.
>>>
>> See JEDEC Module 4.20.18 vs 4.20.21 standards.
>>
>> SODIMM 204-pin socket pinout for 64bit non-ECC vs 72bit ECC is already
>> different.
>> Some ground pins have been sacrificed to fit those extra ECC bits in the socket.
>> In other words: no amount of open source will give you ECC SO-DIMM support when
>> PCB was designed otherwise.
>>
>> That board is one of eKabini reference desings, schematics check tells me ECC
>> pins of the APU SOC part are not connected.
>>
>> Kyösti
>
> Thanks a lot for the information! :)
> I had some suspicions about socket/board support too as I think also
> DIMMs have the same issue.
>
> Since I really wanted ECC capability, I'll probably get a PCEngines APU
> with 4GB of RAM, which was designed for ECC and seems to have it enabled
> in their stock firmware (coreboot-based) from the feedback I saw.
>  From the schematics https://pcengines.ch/schema/apu2c.pdf it seems they
> have one screen port connected to a pinout on the board, although stock
> firmware disables it to use less power. Can do without screen too if I
> can't hack it, it's main usage will be network infrastructure anyway.
> Was just a nice bonus.
>
> -Alberto

At this very moment apu2/apu3 4GB models are marketed without ECC support.
Latest available binaryPI build (which contains a fix for ECC) is otherwise not
compatible. You can thank AMD for not even allowing their commercial customers,
who have access to said PI sources under NDA, to distribute fixed builds.

There is no display support.

Kyösti