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With the discovery of a bug in the implementation of TSX, all CPUs designed before that discovery have the extension disabled via microcode.

Half a year later, I haven't found much about new steppings of broadwell that fix the erratum. wikipedia's TSX article says "The bug was fixed in F-0 steppings of the vPro-enabled Core M-5Y70 Broadwell CPU in November 2014", with a link to http://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/core-m-processor-family-spec-update.pdf.

I also found an article saying that Xeon D CPUs will have usable TSX, and that TSX will be available in the upcoming “Haswell-EX” Xeon E7 processors, according to one of Intel's CPU designers.

So the question: which currently available CPUs have a fixed implementation of TSX? Especially, any CPUs that could be put into a budget desktop (not Xeons), but answers detailing which mobile, embedded, system-on-chip, and workstation / server Xeon CPUs have a production-safe TSX implementation are welcome.

BTW, I know TSX is only going to give speedups of a couple % at best on most things. I'm mostly interested for future-proofing, since software might start to make more use of parallelism for things where locking overhead was a killer without TSX.

Also, I couldn't find any definitive answer to when fixed steppings of CPUs will become available, so the Internet is in need of having this information all in one place.

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  • You have basically listed those that do. This seeens to close to a hardware shopping question
    – Ramhound
    Mar 27, 2015 at 23:46
  • Yes, that's why I'm asking. Is there a different stackexchange site that's more appropriate? Should I edit my question to take out the ones I've found so far, and move that to an answer? I'm asking because I don't 100% trust what I've found so far, and I haven't found any authoritative info on when new steppings of existings chips might come out, or already are out.
    – Peter Cordes
    Mar 28, 2015 at 1:38
  • Neither of the two pages I found mentioned the other, so that's why I wanted to collect things in one place.
    – Peter Cordes
    Mar 28, 2015 at 1:40

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Update on this: HLE is disabled on all current CPUs because of the TAA vulnerability. RTM is still usable on CPUs that didn't have it disabled because of bugs, if the OS doesn't disable it.

  • Haswell Xeon E7 series supports TSX. This is the Haswell-EX core, for servers with more than 2 sockets. (Haswell-EP is the up-to-dual socket part, and has broken TSX.)

  • Xeon D (low-power Broadwell) has working TSX.

  • Desktop Broadwell has working TSX on the 5775C part with eDRAM.

  • Skylake has working TSX.

  • Haswell and Haswell-EP have broken TSX. AFAICT, fixed steppings do not exist.

  • All mobile Broadwell parts have broken TSX, AFAICT.

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