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Comment by ceving | Hacker News Reader

Can you give a reference for ECC? I can not find anything about ECC support on the Odroid site.

The version using the 4-core CPU Intel N97, which is specified by Intel as an embedded CPU, certainly has in-band ECC, which was tested by some reviewers of this SBC.

I do not know whether the 8-core version (H4 Ultra) also enables in-band ECC, as for that CPU Intel does not specify embedded uses, so they may disable the ECC support in the factory.

See e.g.:

https://www.cnx-software.com/2024/05/26/odroid-h4-plus-revie...

However, looking right now at:

https://forum.odroid.com/viewtopic.php?f=171&t=48377

I see that someone has enabled successfully in-band ECC on the 8-core ODROID H4 Ultra and has run benchmarks with ECC disabled/enabled. Therefore it appears that in-band ECC support exists on all models.

The results of benchmarks with in-band ECC disabled/enabled may be not representative for real workloads. In-band ECC relies on caching the ECC bits in a dedicated ECC cache, in order to avoid excessive memory accesses. The effectiveness of the ECC cache can be very different for the benchmark and for the real workload, leading to misleading results. Usually for the real workload it is likely that the cache hit-rate will be higher, so the performance drop with in-band ECC enabled will be less conspicuous.

I can confirm that the Odroid H4 Plus also supports in-band ECC. If I remember right, Memtest86 showed different stats when I ran it with in-band ECC enabled/disabled though I didn't have a good way to test that an error was actually corrected.

Some systems allow forcing an ECC error, but assuming that's not available, if you can adjust memory voltages or timings, you can usually encourage errors that way and confirm memtest detects ECC corrections.

All CPUs with ECC support allow the forcing of ECC errors, but unfortunately in recent years the CPU vendors usually do not document how.

Only when they expose this feature in Linux EDAC drivers it becomes possible to do this. In the past Intel had maintained well its Linux EDAC drivers, but AMD had frequently great delays between the launch of a CPU and the update of the drivers. After the many lay-offs at Intel, it is unknown whether in the future their Linux support will remain as good as in the past.

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