{
  "id": 10084201,
  "title": "The lost atomic update on LoongArch LA664",
  "url": "https://urgent.news/2026/09/26/the-lost-atomic-update-on-loongarch-la664",
  "topic": "tech",
  "section": "Tech",
  "published": "2026-09-26T18:44:00.000Z",
  "source": {
    "name": "Lobsters",
    "slug": "lobsters",
    "url": "https://jia.je/hardware/2026/09/24/loongson-cpu-erratum-en/"
  },
  "original_language": "en",
  "account": null,
  "summary": "In February 2026, Wang Miao encountered an issue while packaging the normaliz software for Debian on a LoongArch server. The software's built-in test was stuck in an infinite loop, which Wang Miao traced back to the use of OpenMP's #pragma omp atomic for accumulating a shared variable. The loop's exit condition required the accumulated value to reach a specific number, but the result was always less than that number, causing the infinite loop. Despite the complexity of the code, the team was unable to reduce the issue to a minimal example that could be easily understood, so they shelved the matter. Half a year later, in August, Wang Miao returned to investigate, and they employed an AI-assisted approach to create a stable minimal reproduction of the issue. This investigation revealed that the CPU's atomic add instruction occasionally fails to be atomic, which led to the discovery of a new CPU erratum. Loongson, the manufacturer of the LoongArch processor, acknowledged the issue and released a test firmware fix before National Day (October 1), which should resolve the problem.",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}