0001 .. SPDX-License-Identifier: GPL-2.0
0002
0003 =====================================
0004 General note on [U]EFI x86_64 support
0005 =====================================
0006
0007 The nomenclature EFI and UEFI are used interchangeably in this document.
0008
0009 Although the tools below are _not_ needed for building the kernel,
0010 the needed bootloader support and associated tools for x86_64 platforms
0011 with EFI firmware and specifications are listed below.
0012
0013 1. UEFI specification: http://www.uefi.org
0014
0015 2. Booting Linux kernel on UEFI x86_64 platform requires bootloader
0016 support. Elilo with x86_64 support can be used.
0017
0018 3. x86_64 platform with EFI/UEFI firmware.
0019
0020 Mechanics
0021 ---------
0022
0023 - Build the kernel with the following configuration::
0024
0025 CONFIG_FB_EFI=y
0026 CONFIG_FRAMEBUFFER_CONSOLE=y
0027
0028 If EFI runtime services are expected, the following configuration should
0029 be selected::
0030
0031 CONFIG_EFI=y
0032 CONFIG_EFIVAR_FS=y or m # optional
0033
0034 - Create a VFAT partition on the disk
0035 - Copy the following to the VFAT partition:
0036
0037 elilo bootloader with x86_64 support, elilo configuration file,
0038 kernel image built in first step and corresponding
0039 initrd. Instructions on building elilo and its dependencies
0040 can be found in the elilo sourceforge project.
0041
0042 - Boot to EFI shell and invoke elilo choosing the kernel image built
0043 in first step.
0044 - If some or all EFI runtime services don't work, you can try following
0045 kernel command line parameters to turn off some or all EFI runtime
0046 services.
0047
0048 noefi
0049 turn off all EFI runtime services
0050 reboot_type=k
0051 turn off EFI reboot runtime service
0052
0053 - If the EFI memory map has additional entries not in the E820 map,
0054 you can include those entries in the kernels memory map of available
0055 physical RAM by using the following kernel command line parameter.
0056
0057 add_efi_memmap
0058 include EFI memory map of available physical RAM
