Given a recent security advisory I would like to disable hyperthreading on my Surface Laptop. Presently I have two physical cores providing four logicals. I have read that if I use msconfig.exe boot options, I will actually end up with one physical core and two logicals, whereas I obviously just want two physicals each with one logical. There's no BIOS that I can see on bootup. How can I accomplish this?

  • "There's no BIOS I can see on bootup" - have you tried shutting down, holding volume up, then pressing power? I don't own a Surface, so I don't know if HT controls are available in the BIOS. – Christopher Hostage Aug 23 '18 at 21:33
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    @ChristopherHostage You can obviously chnage the firmware option me that are available but disabling Hyperthreading ain’t one of them on Surface products – Ramhound Aug 24 '18 at 0:17

There's no BIOS that I can see on bootup.

The only way to disable Hyperthreading is if there was an option since there isn't an option Hyperthreading cannot be disabled on Surface products. Disabling every core except one will resolve the vulnerability described in your link.

How can I accomplish this?

Unless Microsoft releases an update to the firmware for your device, that adds an option that allows you to disable Hyperthreading, it cannot be accomplished with the hardware you have. Hyperthreading must be disabled at the hardware level, this can only be done through the firmware of a device, it cannot be accomplished any other way.

From the Intel Core Processor Datasheet, Volume 1, page 38:

This feature must be enabled using the BIOS and requires operating system support.

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