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My BIOS offers me the option to launch an EFI shell, but I have no idea what that is. Does it allow me to turn on CPU flags like VT-x or something similar? Why would I want to use it?

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  • Just check the manual to the motherboard.
    – Ramhound
    Commented May 8, 2013 at 0:50
  • This presentation (PDF. 2010) has "What is the UEFI 2.0 shell?" (page 8).
    – Peter Mortensen
    Commented Mar 1, 2023 at 7:04

1 Answer 1

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The EFI Shell is a "shell" (think of a command prompt or a terminal shell) that a (U)EFI BIOS can boot directly into (instead of your OS), allowing control and scripting of many items including booting scenarios.

Installing an EFI shell in an "EFI System" partition (type EF00) formatted with a VFAT file system and properly named shellx64.efi for a 64-bit system will allow you to boot directly into it from your BIOS.

See Basic Instructions for Using the Extensible Firmware Interface (EFI)] (PDF)

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    Thanks for the better answer than mine. The only thing I would add is the shell looks like a mini-OS and not able to configure 'BIOS' type settings the OP was asking about.
    – Brad Patton
    Commented May 8, 2013 at 13:16
  • why does it need to be properly named shellx64.efi - is there a default action to that locates the shell and makes it available on that (path)name?
    – user373230
    Commented Jan 9, 2018 at 9:27
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    the link is dead
    – styrofoam fly
    Commented Aug 15, 2019 at 8:23
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    What it can set does depend on your BIOS, but many do allow features to be adjusted that can't be from the general menu. The only way to know what it allows access to is to look.
    – Robert Wm Ruedisueli
    Commented Jun 14, 2021 at 11:55
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    As of 2023-06, the link is working.
    – nealmcb
    Commented Jun 3, 2023 at 13:27

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