Intel’s fix for Spectre variant 2 – the branch target injection design flaw affecting most of its processor chips – is not to fix it.

Rather than preventing abuse of processor branch prediction by disabling the capability and incurring a performance hit, Chipzilla’s future chips – at least for a few years until microarchitecture changes can be implemented – will ship vulnerable by default but will include a protection flag that can be set by software.

Intel explained its approach in its technical note about Spectre mitigation, titled Speculative Execution Side Channel Mitigations. Instead of treating Spectre as a bug, the chip maker is offering Spectre protection as a feature.

The decision to address the flaw with an opt-in flag rather than activating defenses by default has left Linux kernel steward Linus Torvalds apoplectic.

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