Brendan (btrotter.delete@this.gmail.com) on April 1, 2021 5:23 pm wrote:
> none (none.delete@this.none.com) on April 1, 2021 4:31 am wrote:
> >
> > Is there some benchmark not coming from one of the interested parties?
> >
> > BTW I thought all Haswell had TSX disabled by a microcode patch. Was it not the case for
> > Haswell E?
>
> There are only 3 cases:
>
> a) The CPU never attempted to support TSX in the first place (all
> AMD CPUs, all old Intel CPUs, recent desktop/laptop Intel CPUs).
>
> b) It was proven faulty, a micro-code patch to disable it was released, some people installed the micro-code
> patch and some didn't, and software has no idea if "CPUID's feature flag says it's supported" means that
> it can be used safely (because there's no sane way to determine if the relevant micro-code patch was/wasn't
> installed). This is mostly all Haswell (including Haswell E), and Broadwell and Skylake.
>
> c) It hasn't been proven faulty yet, a micro-code patch to disable it hasn't been released yet, and software
> has no idea if "CPUID's feature flag says it's supported" means that it can be used safely. This mainly
> happens because nobody cares about proving it's faulty anymore, partly due to unrelated problems (meltdown,
> spectre, zombieload, etc) causing an increase in risk aversion among software developers.
>
> - Brendan
>


Very accurate summary of the status.