What is “launch efi shell from filesystem device” from the boot manager?

1. Format a USB device in FAT32.
2. Create a directory on the USB device: /efi/boot/
3. Copy the file shell. efi to the directory created above. …
4. Rename the file shell.efi to BOOTX64.efi.
5. Restart the system and enter the UEFI menu.
6. Select the option to Boot from USB.

BIOS tour of ASUS X540S laptop

Launching the Recovery Environment from an EFI shell

Prepare an ESP on a USB drive, and copy an EFI shell on it.

The following example is about creating a small 128 MiB partition from a linux system and copying an x86_64 Shell.efi binary on it:

Then launch the shell from the firmware setup menu of the Windows machine: there should be an item in the Save & Exit menu called Launch EFI Shell from filesystem device.

In the Hardware recovery button documentation it is explained what pressing the button does at a software level: the firmware will call bootmgfw.efi /RecoveryBCD, so this can be also done manually from an EFI shell, like this:

Launching the Windows Recovery Environment by

A friend of mine had a problem with his Windows 10 installation: the system booted but it was unresponsive, so it was not possible to enter the Windows Recovery Environment from Windows.

One thing to notice is that Windows 10 disables by default the familiar F8 boot menu, it can be re-enabled from a working installation, but that was not our case.

Here are, just for reference, some ways to force the system to enter the Windows Recovery Environment in Windows 10, listed in order of increasing desperation :).

Remember that Secure Boot needs to be disabled from the UEFI firmware menu in order to launch an EFI shell.

Manufacturers can set up a Hardware recovery button to launch the Recovery Environment, and ideally they would also document what the button is!

In this case the computer was an Asus X553M laptop and we could not find any info about a key sequence to launch the Recovery Environment at boot (the usual F9 does not work).

By trial and error it turned out that either F10 or F11 —sometimes— work, but they have to be pressed before pressing the power button and kept pressed for a while, pressing the key intermittently apparently is not enough.

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