xref: /openbmc/linux/drivers/firmware/efi/Kconfig (revision b285d2ae) 
1# SPDX-License-Identifier: GPL-2.0-only
2menu "EFI (Extensible Firmware Interface) Support"
3	depends on EFI
4
5config EFI_VARS
6	tristate "EFI Variable Support via sysfs"
7	depends on EFI
8	default n
9	help
10	  If you say Y here, you are able to get EFI (Extensible Firmware
11	  Interface) variable information via sysfs.  You may read,
12	  write, create, and destroy EFI variables through this interface.
13
14	  Note that using this driver in concert with efibootmgr requires
15	  at least test release version 0.5.0-test3 or later, which is
16	  available from:
17	  <http://linux.dell.com/efibootmgr/testing/efibootmgr-0.5.0-test3.tar.gz>
18
19	  Subsequent efibootmgr releases may be found at:
20	  <http://github.com/vathpela/efibootmgr>
21
22config EFI_ESRT
23	bool
24	depends on EFI && !IA64
25	default y
26
27config EFI_VARS_PSTORE
28	tristate "Register efivars backend for pstore"
29	depends on EFI_VARS && PSTORE
30	default y
31	help
32	  Say Y here to enable use efivars as a backend to pstore. This
33	  will allow writing console messages, crash dumps, or anything
34	  else supported by pstore to EFI variables.
35
36config EFI_VARS_PSTORE_DEFAULT_DISABLE
37	bool "Disable using efivars as a pstore backend by default"
38	depends on EFI_VARS_PSTORE
39	default n
40	help
41	  Saying Y here will disable the use of efivars as a storage
42	  backend for pstore by default. This setting can be overridden
43	  using the efivars module's pstore_disable parameter.
44
45config EFI_RUNTIME_MAP
46	bool "Export efi runtime maps to sysfs"
47	depends on X86 && EFI && KEXEC_CORE
48	default y
49	help
50	  Export efi runtime memory maps to /sys/firmware/efi/runtime-map.
51	  That memory map is used for example by kexec to set up efi virtual
52	  mapping the 2nd kernel, but can also be used for debugging purposes.
53
54	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
55
56config EFI_FAKE_MEMMAP
57	bool "Enable EFI fake memory map"
58	depends on EFI && X86
59	default n
60	help
61	  Saying Y here will enable "efi_fake_mem" boot option.
62	  By specifying this parameter, you can add arbitrary attribute
63	  to specific memory range by updating original (firmware provided)
64	  EFI memmap.
65	  This is useful for debugging of EFI memmap related feature.
66	  e.g. Address Range Mirroring feature.
67
68config EFI_MAX_FAKE_MEM
69	int "maximum allowable number of ranges in efi_fake_mem boot option"
70	depends on EFI_FAKE_MEMMAP
71	range 1 128
72	default 8
73	help
74	  Maximum allowable number of ranges in efi_fake_mem boot option.
75	  Ranges can be set up to this value using comma-separated list.
76	  The default value is 8.
77
78config EFI_SOFT_RESERVE
79	bool "Reserve EFI Specific Purpose Memory"
80	depends on EFI && EFI_STUB && ACPI_HMAT
81	default ACPI_HMAT
82	help
83	  On systems that have mixed performance classes of memory EFI
84	  may indicate specific purpose memory with an attribute (See
85	  EFI_MEMORY_SP in UEFI 2.8). A memory range tagged with this
86	  attribute may have unique performance characteristics compared
87	  to the system's general purpose "System RAM" pool. On the
88	  expectation that such memory has application specific usage,
89	  and its base EFI memory type is "conventional" answer Y to
90	  arrange for the kernel to reserve it as a "Soft Reserved"
91	  resource, and set aside for direct-access (device-dax) by
92	  default. The memory range can later be optionally assigned to
93	  the page allocator by system administrator policy via the
94	  device-dax kmem facility. Say N to have the kernel treat this
95	  memory as "System RAM" by default.
96
97	  If unsure, say Y.
98
99config EFI_PARAMS_FROM_FDT
100	bool
101	help
102	  Select this config option from the architecture Kconfig if
103	  the EFI runtime support gets system table address, memory
104          map address, and other parameters from the device tree.
105
106config EFI_RUNTIME_WRAPPERS
107	bool
108
109config EFI_GENERIC_STUB
110	bool
111
112config EFI_ARMSTUB_DTB_LOADER
113	bool "Enable the DTB loader"
114	depends on EFI_GENERIC_STUB
115	default y
116	help
117	  Select this config option to add support for the dtb= command
118	  line parameter, allowing a device tree blob to be loaded into
119	  memory from the EFI System Partition by the stub.
120
121	  If the device tree is provided by the platform or by
122	  the bootloader this option may not be needed.
123	  But, for various development reasons and to maintain existing
124	  functionality for bootloaders that do not have such support
125	  this option is necessary.
126
127config EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER
128	bool "Enable the command line initrd loader" if !X86
129	depends on EFI_STUB && (EFI_GENERIC_STUB || X86)
130	default y
131	help
132	  Select this config option to add support for the initrd= command
133	  line parameter, allowing an initrd that resides on the same volume
134	  as the kernel image to be loaded into memory.
135
136	  This method is deprecated.
137
138config EFI_BOOTLOADER_CONTROL
139	tristate "EFI Bootloader Control"
140	depends on EFI_VARS
141	default n
142	help
143	  This module installs a reboot hook, such that if reboot() is
144	  invoked with a string argument NNN, "NNN" is copied to the
145	  "LoaderEntryOneShot" EFI variable, to be read by the
146	  bootloader. If the string matches one of the boot labels
147	  defined in its configuration, the bootloader will boot once
148	  to that label. The "LoaderEntryRebootReason" EFI variable is
149	  set with the reboot reason: "reboot" or "shutdown". The
150	  bootloader reads this reboot reason and takes particular
151	  action according to its policy.
152
153config EFI_CAPSULE_LOADER
154	tristate "EFI capsule loader"
155	depends on EFI
156	help
157	  This option exposes a loader interface "/dev/efi_capsule_loader" for
158	  users to load EFI capsules. This driver requires working runtime
159	  capsule support in the firmware, which many OEMs do not provide.
160
161	  Most users should say N.
162
163config EFI_CAPSULE_QUIRK_QUARK_CSH
164	bool "Add support for Quark capsules with non-standard headers"
165	depends on X86 && !64BIT
166	select EFI_CAPSULE_LOADER
167	default y
168	help
169	  Add support for processing Quark X1000 EFI capsules, whose header
170	  layout deviates from the layout mandated by the UEFI specification.
171
172config EFI_TEST
173	tristate "EFI Runtime Service Tests Support"
174	depends on EFI
175	default n
176	help
177	  This driver uses the efi.<service> function pointers directly instead
178	  of going through the efivar API, because it is not trying to test the
179	  kernel subsystem, just for testing the UEFI runtime service
180	  interfaces which are provided by the firmware. This driver is used
181	  by the Firmware Test Suite (FWTS) for testing the UEFI runtime
182	  interfaces readiness of the firmware.
183	  Details for FWTS are available from:
184	  <https://wiki.ubuntu.com/FirmwareTestSuite>
185
186	  Say Y here to enable the runtime services support via /dev/efi_test.
187	  If unsure, say N.
188
189config APPLE_PROPERTIES
190	bool "Apple Device Properties"
191	depends on EFI_STUB && X86
192	select EFI_DEV_PATH_PARSER
193	select UCS2_STRING
194	help
195	  Retrieve properties from EFI on Apple Macs and assign them to
196	  devices, allowing for improved support of Apple hardware.
197	  Properties that would otherwise be missing include the
198	  Thunderbolt Device ROM and GPU configuration data.
199
200	  If unsure, say Y if you have a Mac.  Otherwise N.
201
202config RESET_ATTACK_MITIGATION
203	bool "Reset memory attack mitigation"
204	depends on EFI_STUB
205	help
206	  Request that the firmware clear the contents of RAM after a reboot
207	  using the TCG Platform Reset Attack Mitigation specification. This
208	  protects against an attacker forcibly rebooting the system while it
209	  still contains secrets in RAM, booting another OS and extracting the
210	  secrets. This should only be enabled when userland is configured to
211	  clear the MemoryOverwriteRequest flag on clean shutdown after secrets
212	  have been evicted, since otherwise it will trigger even on clean
213	  reboots.
214
215config EFI_RCI2_TABLE
216	bool "EFI Runtime Configuration Interface Table Version 2 Support"
217	depends on X86 || COMPILE_TEST
218	help
219	  Displays the content of the Runtime Configuration Interface
220	  Table version 2 on Dell EMC PowerEdge systems as a binary
221	  attribute 'rci2' under /sys/firmware/efi/tables directory.
222
223	  RCI2 table contains BIOS HII in XML format and is used to populate
224	  BIOS setup page in Dell EMC OpenManage Server Administrator tool.
225	  The BIOS setup page contains BIOS tokens which can be configured.
226
227	  Say Y here for Dell EMC PowerEdge systems.
228
229config EFI_DISABLE_PCI_DMA
230       bool "Clear Busmaster bit on PCI bridges during ExitBootServices()"
231       help
232	  Disable the busmaster bit in the control register on all PCI bridges
233	  while calling ExitBootServices() and passing control to the runtime
234	  kernel. System firmware may configure the IOMMU to prevent malicious
235	  PCI devices from being able to attack the OS via DMA. However, since
236	  firmware can't guarantee that the OS is IOMMU-aware, it will tear
237	  down IOMMU configuration when ExitBootServices() is called. This
238	  leaves a window between where a hostile device could still cause
239	  damage before Linux configures the IOMMU again.
240
241	  If you say Y here, the EFI stub will clear the busmaster bit on all
242	  PCI bridges before ExitBootServices() is called. This will prevent
243	  any malicious PCI devices from being able to perform DMA until the
244	  kernel reenables busmastering after configuring the IOMMU.
245
246	  This option will cause failures with some poorly behaved hardware
247	  and should not be enabled without testing. The kernel commandline
248	  options "efi=disable_early_pci_dma" or "efi=no_disable_early_pci_dma"
249	  may be used to override this option.
250
251endmenu
252
253config EFI_EMBEDDED_FIRMWARE
254	bool
255	depends on EFI
256	select CRYPTO_LIB_SHA256
257
258config UEFI_CPER
259	bool
260
261config UEFI_CPER_ARM
262	bool
263	depends on UEFI_CPER && ( ARM || ARM64 )
264	default y
265
266config UEFI_CPER_X86
267	bool
268	depends on UEFI_CPER && X86
269	default y
270
271config EFI_DEV_PATH_PARSER
272	bool
273	depends on ACPI
274	default n
275
276config EFI_EARLYCON
277	def_bool y
278	depends on SERIAL_EARLYCON && !ARM && !IA64
279	select FONT_SUPPORT
280	select ARCH_USE_MEMREMAP_PROT
281
282config EFI_CUSTOM_SSDT_OVERLAYS
283	bool "Load custom ACPI SSDT overlay from an EFI variable"
284	depends on EFI_VARS && ACPI
285	default ACPI_TABLE_UPGRADE
286	help
287	  Allow loading of an ACPI SSDT overlay from an EFI variable specified
288	  by a kernel command line option.
289
290	  See Documentation/admin-guide/acpi/ssdt-overlays.rst for more
291	  information.
292