On Fri, Jul 18, 2025 at 5:35 PM H. Hartzer <h@hartzer.sh> wrote:
> I have a Intel Atom S1260 system that I finally installed OpenBSD on. It
> boots and shows that Meltdown issues are noticed, and I assume that
> Meltdown mitigations are turned on.
>
> This is not useful, however, because this processor has in-order
> execution and is not subject to these vulnerabilities.
>
> Poking around replacemeltdown() in sys/arch/amd64/amd64/cpu.c, what's
> concerning is that if the comments are correct, the mitigation
> exceptions exist for vulnerable processors.
>
> Silvermont and Airmont are mentioned, which are out of order processors
> that I believe suffer from this slew of issues.
>
> I'm not sure how to identify processor families and models, but this
> seems like it may be a fairly simple fix to speed up the older Atom
> processors (Bonnell) and secure/slow down the newer Atoms listed.
>
> Does sysctl machdep.cpuid provide the family/model info?

Family/model info, as well as relevant cpuid values, can be found in
the dmesg.  Look for the lines beginning with "cpu0:".


Philip Guenther