Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

# SPDX-License-Identifier: GPL-2.0-only
menu "EFI (Extensible Firmware Interface) Support"
	depends on CONFIG_EFI

config CONFIG_EFI_VARS
	tristate "EFI Variable Support via sysfs"
	depends on CONFIG_EFI
	default n
	help
	  If you say Y here, you are able to get CONFIG_EFI (Extensible Firmware
	  Interface) variable information via sysfs.  You may read,
	  write, create, and destroy CONFIG_EFI variables through this interface.

	  Note that using this driver in concert with efibootmgr requires
	  at least test release version 0.5.0-test3 or later, which is
	  available from:
	  <http://linux.dell.com/efibootmgr/testing/efibootmgr-0.5.0-test3.tar.gz>

	  Subsequent efibootmgr releases may be found at:
	  <http://github.com/vathpela/efibootmgr>

config CONFIG_EFI_ESRT
	bool
	depends on CONFIG_EFI && !CONFIG_IA64
	default y

config CONFIG_EFI_VARS_PSTORE
	tristate "Register efivars backend for pstore"
	depends on CONFIG_EFI_VARS && CONFIG_PSTORE
	default y
	help
	  Say Y here to enable use efivars as a backend to pstore. This
	  will allow writing console messages, crash dumps, or anything
	  else supported by pstore to CONFIG_EFI variables.

config CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE
	bool "Disable using efivars as a pstore backend by default"
	depends on CONFIG_EFI_VARS_PSTORE
	default n
	help
	  Saying Y here will disable the use of efivars as a storage
	  backend for pstore by default. This setting can be overridden
	  using the efivars module's pstore_disable parameter.

config CONFIG_EFI_RUNTIME_MAP
	bool "Export efi runtime maps to sysfs"
	depends on CONFIG_X86 && CONFIG_EFI && CONFIG_KEXEC_CORE
	default y
	help
	  Export efi runtime memory maps to /sys/firmware/efi/runtime-map.
	  That memory map is used for example by kexec to set up efi virtual
	  mapping the 2nd kernel, but can also be used for debugging purposes.

	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.

config CONFIG_EFI_FAKE_MEMMAP
	bool "Enable EFI fake memory map"
	depends on CONFIG_EFI && CONFIG_X86
	default n
	help
	  Saying Y here will enable "efi_fake_mem" boot option.
	  By specifying this parameter, you can add arbitrary attribute
	  to specific memory range by updating original (firmware provided)
	  CONFIG_EFI memmap.
	  This is useful for debugging of CONFIG_EFI memmap related feature.
	  e.g. Address Range Mirroring feature.

config CONFIG_EFI_MAX_FAKE_MEM
	int "maximum allowable number of ranges in efi_fake_mem boot option"
	depends on CONFIG_EFI_FAKE_MEMMAP
	range 1 128
	default 8
	help
	  Maximum allowable number of ranges in efi_fake_mem boot option.
	  Ranges can be set up to this value using comma-separated list.
	  The default value is 8.

config CONFIG_EFI_PARAMS_FROM_FDT
	bool
	help
	  Select this config option from the architecture Kconfig if
	  the CONFIG_EFI runtime support gets system table address, memory
          map address, and other parameters from the device tree.

config CONFIG_EFI_RUNTIME_WRAPPERS
	bool

config CONFIG_EFI_ARMSTUB
	bool

config CONFIG_EFI_ARMSTUB_DTB_LOADER
	bool "Enable the DTB loader"
	depends on CONFIG_EFI_ARMSTUB
	default y
	help
	  Select this config option to add support for the dtb= command
	  line parameter, allowing a device tree blob to be loaded into
	  memory from the CONFIG_EFI System Partition by the stub.

	  If the device tree is provided by the platform or by
	  the bootloader this option may not be needed.
	  But, for various development reasons and to maintain existing
	  functionality for bootloaders that do not have such support
	  this option is necessary.

config CONFIG_EFI_BOOTLOADER_CONTROL
	tristate "EFI Bootloader Control"
	depends on CONFIG_EFI_VARS
	default n
	---help---
	  This module installs a reboot hook, such that if reboot() is
	  invoked with a string argument NNN, "NNN" is copied to the
	  "LoaderEntryOneShot" CONFIG_EFI variable, to be read by the
	  bootloader. If the string matches one of the boot labels
	  defined in its configuration, the bootloader will boot once
	  to that label. The "LoaderEntryRebootReason" CONFIG_EFI variable is
	  set with the reboot reason: "reboot" or "shutdown". The
	  bootloader reads this reboot reason and takes particular
	  action according to its policy.

config CONFIG_EFI_CAPSULE_LOADER
	tristate "EFI capsule loader"
	depends on CONFIG_EFI
	help
	  This option exposes a loader interface "/dev/efi_capsule_loader" for
	  users to load CONFIG_EFI capsules. This driver requires working runtime
	  capsule support in the firmware, which many OEMs do not provide.

	  Most users should say N.

config CONFIG_EFI_CAPSULE_QUIRK_QUARK_CSH
	bool "Add support for Quark capsules with non-standard headers"
	depends on CONFIG_X86 && !CONFIG_64BIT
	select CONFIG_EFI_CAPSULE_LOADER
	default y
	help
	  Add support for processing Quark X1000 CONFIG_EFI capsules, whose header
	  layout deviates from the layout mandated by the UEFI specification.

config CONFIG_EFI_TEST
	tristate "EFI Runtime Service Tests Support"
	depends on CONFIG_EFI
	default n
	help
	  This driver uses the efi.<service> function pointers directly instead
	  of going through the efivar API, because it is not trying to test the
	  kernel subsystem, just for testing the UEFI runtime service
	  interfaces which are provided by the firmware. This driver is used
	  by the Firmware Test Suite (FWTS) for testing the UEFI runtime
	  interfaces readiness of the firmware.
	  Details for FWTS are available from:
	  <https://wiki.ubuntu.com/FirmwareTestSuite>

	  Say Y here to enable the runtime services support via /dev/efi_test.
	  If unsure, say N.

config CONFIG_APPLE_PROPERTIES
	bool "Apple Device Properties"
	depends on CONFIG_EFI_STUB && CONFIG_X86
	select CONFIG_EFI_DEV_PATH_PARSER
	select CONFIG_UCS2_STRING
	help
	  Retrieve properties from CONFIG_EFI on Apple Macs and assign them to
	  devices, allowing for improved support of Apple hardware.
	  Properties that would otherwise be missing include the
	  Thunderbolt Device CONFIG_ROM and GPU configuration data.

	  If unsure, say Y if you have a Mac.  Otherwise N.

config CONFIG_RESET_ATTACK_MITIGATION
	bool "Reset memory attack mitigation"
	depends on CONFIG_EFI_STUB
	help
	  Request that the firmware clear the contents of RAM after a reboot
	  using the TCG Platform Reset Attack Mitigation specification. This
	  protects against an attacker forcibly rebooting the system while it
	  still contains secrets in RAM, booting another OS and extracting the
	  secrets. This should only be enabled when userland is configured to
	  clear the MemoryOverwriteRequest flag on clean shutdown after secrets
	  have been evicted, since otherwise it will trigger even on clean
	  reboots.

config CONFIG_EFI_RCI2_TABLE
	bool "EFI Runtime Configuration Interface Table Version 2 Support"
	depends on CONFIG_X86 || CONFIG_COMPILE_TEST
	help
	  Displays the content of the Runtime Configuration Interface
	  Table version 2 on Dell EMC PowerEdge systems as a binary
	  attribute 'rci2' under /sys/firmware/efi/tables directory.

	  RCI2 table contains BIOS HII in XML format and is used to populate
	  BIOS setup page in Dell EMC OpenManage Server Administrator tool.
	  The BIOS setup page contains BIOS tokens which can be configured.

	  Say Y here for Dell EMC PowerEdge systems.

endmenu

config CONFIG_UEFI_CPER
	bool

config CONFIG_UEFI_CPER_ARM
	bool
	depends on CONFIG_UEFI_CPER && ( CONFIG_ARM || CONFIG_ARM64 )
	default y

config CONFIG_UEFI_CPER_X86
	bool
	depends on CONFIG_UEFI_CPER && CONFIG_X86
	default y

config CONFIG_EFI_DEV_PATH_PARSER
	bool
	depends on CONFIG_ACPI
	default n

config CONFIG_EFI_EARLYCON
	def_bool y
	depends on CONFIG_SERIAL_EARLYCON && !CONFIG_ARM && !CONFIG_IA64
	select CONFIG_FONT_SUPPORT
	select CONFIG_ARCH_USE_MEMREMAP_PROT