**What is an EFI stub?** An EFI stub is *a kernel in the form of an EFI executable which can be directly booted from UEFI firmware.* > **Is a bootloader required for EFI stubs?** > *No*, a bootloader isn't required for EFI stubs. # Kernel configuration **What kernel configuration options must be enabled for EFI stub support?** The kernel configuration options that must be enabled for EFI stub support are: * EFI runtime service support (`CONFIG_EFI`). * EFI stub support (`CONFIG_EFI_STUB`). * EFI mixed-mode support (`CONFIG_EFI_MIXED`) - This setting is only required if you're booting a 64-bit kernel from 32-bit firmware, the CPU supports 64-bit mode, and EFI handover is enabled. # Installation **What partition do you have to create in order to use an EFI stub?** The partition you have to create in order to use an EFI stub is *an EFI System Partition (ESP).* # Automated **What should you keep in mind with EFI stub booting and different UEFI vendors?** With EFI stub booting and different UEFI vendors, you should keep in mind that *it's not guaranteed to work for all UEFI systems.* **What package provides automated EFI stub booting?** The package that provides automated EFI stub booting is *`sys-kernel/installkernel-38`.* > **What USE flag needs to be enabled in order for `installkernel-38` to set up EFI stub booting?** > In order for `installkernel-38` to set up EFI stub booting, the USE flag that needs to be enable is *the `efistub` USE flag.* > > **What does `installkernel-38` do when the `efistub` USE flag is enabled?** > When the `efistub` USE flag is enabled, `installkernel-38` *relocates the regular boot layout from `/boot` to the `EFI/Gentoo` directory on the ESP.* ...