Intel releases new Spectre microcode update for Skylake; other chips remain in beta

Enlarge / Intel Skylake Core i7-6700K. (credit: Orestis Bastounis)

After recommending customers not use its microcode fix for Broadwell and Haswell chips, Intel has issued a new microcode update for Skylake processors that gives operating systems the ability to protect against the Spectre flaw revealed earlier this year.

The Spectre attacks work by persuading a processor's branch predictor to make a specific bad prediction. This bad prediction can then be used to infer the value of data stored in memory, which, in turn, gives an attacker information that they shouldn't otherwise have. The microcode update is designed to give operating systems greater control over the branch predictor, enabling them to prevent one process from influencing the predictions made in another process.

Intel's first microcode update, developed late last year, was included in system firmware updates for machines with Broadwell, Haswell, Skylake, Kaby Lake, and Coffee Lake processors. But users subsequently discovered that the update was causing systems to crash and reboot. Initially, only Broadwell and Haswell systems were confirmed to be affected, but further examination determined that Skylake, Kaby Lake, and Coffee Lake systems were rebooting, too.

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