1.. SPDX-License-Identifier: GPL-2.0 2 3===================================== 4General note on [U]EFI x86_64 support 5===================================== 6 7The nomenclature EFI and UEFI are used interchangeably in this document. 8 9Although the tools below are _not_ needed for building the kernel, 10the needed bootloader support and associated tools for x86_64 platforms 11with EFI firmware and specifications are listed below. 12 131. UEFI specification: http://www.uefi.org 14 152. Booting Linux kernel on UEFI x86_64 platform requires bootloader 16 support. Elilo with x86_64 support can be used. 17 183. x86_64 platform with EFI/UEFI firmware. 19 20Mechanics 21--------- 22 23- Build the kernel with the following configuration:: 24 25 CONFIG_FB_EFI=y 26 CONFIG_FRAMEBUFFER_CONSOLE=y 27 28 If EFI runtime services are expected, the following configuration should 29 be selected:: 30 31 CONFIG_EFI=y 32 CONFIG_EFI_VARS=y or m # optional 33 34- Create a VFAT partition on the disk 35- Copy the following to the VFAT partition: 36 37 elilo bootloader with x86_64 support, elilo configuration file, 38 kernel image built in first step and corresponding 39 initrd. Instructions on building elilo and its dependencies 40 can be found in the elilo sourceforge project. 41 42- Boot to EFI shell and invoke elilo choosing the kernel image built 43 in first step. 44- If some or all EFI runtime services don't work, you can try following 45 kernel command line parameters to turn off some or all EFI runtime 46 services. 47 48 noefi 49 turn off all EFI runtime services 50 reboot_type=k 51 turn off EFI reboot runtime service 52 53- If the EFI memory map has additional entries not in the E820 map, 54 you can include those entries in the kernels memory map of available 55 physical RAM by using the following kernel command line parameter. 56 57 add_efi_memmap 58 include EFI memory map of available physical RAM 59