AMD’s Ryzen 7 has been generally well-received by the enthusiast community, but there’s been one low-level problem that we’ve been watching but haven’t previously reported on. In early June, Ryzen users running Linux began reporting segmentation faults when running multiple concurrent compilation workloads using multiple different versions of GCC. LVVM/Clang was not affected, and the issue appears confined to Linux. Moreover, it wasn’t apparently common, even among Linux users — Michael Larabel, of Phoronix.com, reported that his own test rigs had been absolutely solid, even under heavy workloads.
Like the Pentium FDIV bug of yesteryear, this was a real issue, but one that realistically only impacted a fraction of a fraction of buyers. AMD had previously said it was investigating the problem (which isn’t present on any Epyc or Threadripper CPUs) and it’s now announced a solution: CPU replacement.
Phoronix reports AMD provided them with a new Ryzen 7 1800X CPU and that this chip has refused to crash, even when running a “kill Ryzen” script that would previously deliberately create a compiler segmentation fault. While some users thought the issue was confined to a RAM, motherboard, or BIOS-related issue, Phoronix’s testing proves otherwise. Swap the new Ryzen 7 1800X for an older part, and the problem reappears. Switch back to the new chip, and it vanishes. Larabel has tentatively concluded that the issue appears confined to Ryzen CPUs manufactured before Week 25 of this year (the new chip was built in Week 30), but no other details on what caused it are available.
The good news is, AMD is replacing the CPUs of anyone who has this issue. Again, while the issue is real, it appears to only trigger in an extremely small number of cases when running a Linux workload under specific and particular circumstances.