Subj : Re: Any sign of notifiable ECC support on Pi 5 or CM5?
To   : All
From : James Harris
Date : Tue Dec 02 2025 10:52:57

On 01/12/2025 22:43, Mike Easter wrote:
> James Harris wrote:
>> That's good. But do they inform the OS of when there are corrections
>> and uncorrectable errors?
> 
> Not that I 'rely' on the tools I use...
> 
> gglAIov:
>> The Raspberry Pi Compute Module 5 (CM5) supports on-die ECC (Error
>> Correction Code), which silently corrects single-bit errors but does
>> not report them to the operating system. This is different from
>> traditional ECC, which would also report errors. The Pi5 does not
>> support traditional ECC with OS-level error reporting, so while
>> errors are corrected, the system won't be alerted to potential
>> issues with the RAM

I take it you mean that that's from an AI engine and they are not 
reliable. If so, agreed in spades. FWIW the following is where Grok told 
me that on CM5 ECC was integrated with the OS. It's quite categoric. But 
is it true?

--- Start ---

"Unlike the standard Raspberry Pi 5, the Compute Module 5 exposes the 
ECC side-band signals and the BCM2712 RAS controller, so the Linux EDAC 
driver can report and correct errors." - Raspberry Pi Forums Thread 
(November 2024): James Adams (Head of Compute Module Engineering).

....

Jeff Geerling's Testing (Blog/Video, December 2024): He verified this 
hands-on by injecting errors and logging corrections with the 
brcmstb_edac driver on a CM5 prototype.

....

Linux Kernel Documentation: The merged EDAC driver (Linux 6.12+) 
explicitly supports BCM2712 ECC on CM5 (but not standard Pi 5), with 
details on how it reads RAS registers for error counts.... (search for 
"brcmstb_edac" commits).

--- End ---

As you can see, it does say clearly that Linux can handle ECC reports on 
the CM5 but thus far I've not found any sources to back it up.


-- 
James Harris



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