FreeBSD Finally Gets Mitigated For Spectre & Meltdown
Written by Michael Larabel in BSD on 17 February 2018 at 04:13 PM EST. 153 Comments
BSD --
Landing in FreeBSD today was the mitigation work for the Meltdown and Spectre CPU vulnerabilities.

It's taken a few more weeks longer than most of the Linux distributions to be re-worked for Spectre/Meltdown mitigation as well as DragonFlyBSD, but with FreeBSD Revision 329462 it appears their initial fixes are in place.

There is Meltdown mitigation for Intel CPUs via a KPTI implementation similar to Linux, the Kernel Page Table Isolation. There is also a PCID (Process Context Identifier) optimization for Intel Westmere CPUs and newer, just as was also done on Linux.

For their Spectre mitigation they are currently making use of IBRS: Indirect Branch Restricted Speculation. The IBRS feature just as with Linux requires support from the CPU microcode and is for mitigating the Variant Two vulnerability as an alternative to Retpolines.

Their stable 11 code can be found here. Given the severity of Spectre and Meltdown, I wouldn't be surprised if they end up shipping a new stable point release soon.

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Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter or contacted via

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