xref: /openbmc/linux/drivers/firmware/efi/Kconfig (revision 11a163f2) 
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 && (X86 || IA64)
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	  Note that this driver is only retained for compatibility with
14	  legacy users: new users should use the efivarfs filesystem
15	  instead.
16
17config EFI_ESRT
18	bool
19	depends on EFI && !IA64
20	default y
21
22config EFI_VARS_PSTORE
23	tristate "Register efivars backend for pstore"
24	depends on PSTORE
25	default y
26	help
27	  Say Y here to enable use efivars as a backend to pstore. This
28	  will allow writing console messages, crash dumps, or anything
29	  else supported by pstore to EFI variables.
30
31config EFI_VARS_PSTORE_DEFAULT_DISABLE
32	bool "Disable using efivars as a pstore backend by default"
33	depends on EFI_VARS_PSTORE
34	default n
35	help
36	  Saying Y here will disable the use of efivars as a storage
37	  backend for pstore by default. This setting can be overridden
38	  using the efivars module's pstore_disable parameter.
39
40config EFI_RUNTIME_MAP
41	bool "Export efi runtime maps to sysfs"
42	depends on X86 && EFI && KEXEC_CORE
43	default y
44	help
45	  Export efi runtime memory maps to /sys/firmware/efi/runtime-map.
46	  That memory map is used for example by kexec to set up efi virtual
47	  mapping the 2nd kernel, but can also be used for debugging purposes.
48
49	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
50
51config EFI_FAKE_MEMMAP
52	bool "Enable EFI fake memory map"
53	depends on EFI && X86
54	default n
55	help
56	  Saying Y here will enable "efi_fake_mem" boot option.
57	  By specifying this parameter, you can add arbitrary attribute
58	  to specific memory range by updating original (firmware provided)
59	  EFI memmap.
60	  This is useful for debugging of EFI memmap related feature.
61	  e.g. Address Range Mirroring feature.
62
63config EFI_MAX_FAKE_MEM
64	int "maximum allowable number of ranges in efi_fake_mem boot option"
65	depends on EFI_FAKE_MEMMAP
66	range 1 128
67	default 8
68	help
69	  Maximum allowable number of ranges in efi_fake_mem boot option.
70	  Ranges can be set up to this value using comma-separated list.
71	  The default value is 8.
72
73config EFI_SOFT_RESERVE
74	bool "Reserve EFI Specific Purpose Memory"
75	depends on EFI && EFI_STUB && ACPI_HMAT
76	default ACPI_HMAT
77	help
78	  On systems that have mixed performance classes of memory EFI
79	  may indicate specific purpose memory with an attribute (See
80	  EFI_MEMORY_SP in UEFI 2.8). A memory range tagged with this
81	  attribute may have unique performance characteristics compared
82	  to the system's general purpose "System RAM" pool. On the
83	  expectation that such memory has application specific usage,
84	  and its base EFI memory type is "conventional" answer Y to
85	  arrange for the kernel to reserve it as a "Soft Reserved"
86	  resource, and set aside for direct-access (device-dax) by
87	  default. The memory range can later be optionally assigned to
88	  the page allocator by system administrator policy via the
89	  device-dax kmem facility. Say N to have the kernel treat this
90	  memory as "System RAM" by default.
91
92	  If unsure, say Y.
93
94config EFI_PARAMS_FROM_FDT
95	bool
96	help
97	  Select this config option from the architecture Kconfig if
98	  the EFI runtime support gets system table address, memory
99          map address, and other parameters from the device tree.
100
101config EFI_RUNTIME_WRAPPERS
102	bool
103
104config EFI_GENERIC_STUB
105	bool
106
107config EFI_ARMSTUB_DTB_LOADER
108	bool "Enable the DTB loader"
109	depends on EFI_GENERIC_STUB && !RISCV
110	default y
111	help
112	  Select this config option to add support for the dtb= command
113	  line parameter, allowing a device tree blob to be loaded into
114	  memory from the EFI System Partition by the stub.
115
116	  If the device tree is provided by the platform or by
117	  the bootloader this option may not be needed.
118	  But, for various development reasons and to maintain existing
119	  functionality for bootloaders that do not have such support
120	  this option is necessary.
121
122config EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER
123	bool "Enable the command line initrd loader" if !X86
124	depends on EFI_STUB && (EFI_GENERIC_STUB || X86)
125	default y
126	depends on !RISCV
127	help
128	  Select this config option to add support for the initrd= command
129	  line parameter, allowing an initrd that resides on the same volume
130	  as the kernel image to be loaded into memory.
131
132	  This method is deprecated.
133
134config EFI_BOOTLOADER_CONTROL
135	tristate "EFI Bootloader Control"
136	default n
137	help
138	  This module installs a reboot hook, such that if reboot() is
139	  invoked with a string argument NNN, "NNN" is copied to the
140	  "LoaderEntryOneShot" EFI variable, to be read by the
141	  bootloader. If the string matches one of the boot labels
142	  defined in its configuration, the bootloader will boot once
143	  to that label. The "LoaderEntryRebootReason" EFI variable is
144	  set with the reboot reason: "reboot" or "shutdown". The
145	  bootloader reads this reboot reason and takes particular
146	  action according to its policy.
147
148config EFI_CAPSULE_LOADER
149	tristate "EFI capsule loader"
150	depends on EFI
151	help
152	  This option exposes a loader interface "/dev/efi_capsule_loader" for
153	  users to load EFI capsules. This driver requires working runtime
154	  capsule support in the firmware, which many OEMs do not provide.
155
156	  Most users should say N.
157
158config EFI_CAPSULE_QUIRK_QUARK_CSH
159	bool "Add support for Quark capsules with non-standard headers"
160	depends on X86 && !64BIT
161	select EFI_CAPSULE_LOADER
162	default y
163	help
164	  Add support for processing Quark X1000 EFI capsules, whose header
165	  layout deviates from the layout mandated by the UEFI specification.
166
167config EFI_TEST
168	tristate "EFI Runtime Service Tests Support"
169	depends on EFI
170	default n
171	help
172	  This driver uses the efi.<service> function pointers directly instead
173	  of going through the efivar API, because it is not trying to test the
174	  kernel subsystem, just for testing the UEFI runtime service
175	  interfaces which are provided by the firmware. This driver is used
176	  by the Firmware Test Suite (FWTS) for testing the UEFI runtime
177	  interfaces readiness of the firmware.
178	  Details for FWTS are available from:
179	  <https://wiki.ubuntu.com/FirmwareTestSuite>
180
181	  Say Y here to enable the runtime services support via /dev/efi_test.
182	  If unsure, say N.
183
184config APPLE_PROPERTIES
185	bool "Apple Device Properties"
186	depends on EFI_STUB && X86
187	select EFI_DEV_PATH_PARSER
188	select UCS2_STRING
189	help
190	  Retrieve properties from EFI on Apple Macs and assign them to
191	  devices, allowing for improved support of Apple hardware.
192	  Properties that would otherwise be missing include the
193	  Thunderbolt Device ROM and GPU configuration data.
194
195	  If unsure, say Y if you have a Mac.  Otherwise N.
196
197config RESET_ATTACK_MITIGATION
198	bool "Reset memory attack mitigation"
199	depends on EFI_STUB
200	help
201	  Request that the firmware clear the contents of RAM after a reboot
202	  using the TCG Platform Reset Attack Mitigation specification. This
203	  protects against an attacker forcibly rebooting the system while it
204	  still contains secrets in RAM, booting another OS and extracting the
205	  secrets. This should only be enabled when userland is configured to
206	  clear the MemoryOverwriteRequest flag on clean shutdown after secrets
207	  have been evicted, since otherwise it will trigger even on clean
208	  reboots.
209
210config EFI_RCI2_TABLE
211	bool "EFI Runtime Configuration Interface Table Version 2 Support"
212	depends on X86 || COMPILE_TEST
213	help
214	  Displays the content of the Runtime Configuration Interface
215	  Table version 2 on Dell EMC PowerEdge systems as a binary
216	  attribute 'rci2' under /sys/firmware/efi/tables directory.
217
218	  RCI2 table contains BIOS HII in XML format and is used to populate
219	  BIOS setup page in Dell EMC OpenManage Server Administrator tool.
220	  The BIOS setup page contains BIOS tokens which can be configured.
221
222	  Say Y here for Dell EMC PowerEdge systems.
223
224config EFI_DISABLE_PCI_DMA
225       bool "Clear Busmaster bit on PCI bridges during ExitBootServices()"
226       help
227	  Disable the busmaster bit in the control register on all PCI bridges
228	  while calling ExitBootServices() and passing control to the runtime
229	  kernel. System firmware may configure the IOMMU to prevent malicious
230	  PCI devices from being able to attack the OS via DMA. However, since
231	  firmware can't guarantee that the OS is IOMMU-aware, it will tear
232	  down IOMMU configuration when ExitBootServices() is called. This
233	  leaves a window between where a hostile device could still cause
234	  damage before Linux configures the IOMMU again.
235
236	  If you say Y here, the EFI stub will clear the busmaster bit on all
237	  PCI bridges before ExitBootServices() is called. This will prevent
238	  any malicious PCI devices from being able to perform DMA until the
239	  kernel reenables busmastering after configuring the IOMMU.
240
241	  This option will cause failures with some poorly behaved hardware
242	  and should not be enabled without testing. The kernel commandline
243	  options "efi=disable_early_pci_dma" or "efi=no_disable_early_pci_dma"
244	  may be used to override this option.
245
246endmenu
247
248config EFI_EMBEDDED_FIRMWARE
249	bool
250	depends on EFI
251	select CRYPTO_LIB_SHA256
252
253config UEFI_CPER
254	bool
255
256config UEFI_CPER_ARM
257	bool
258	depends on UEFI_CPER && ( ARM || ARM64 )
259	default y
260
261config UEFI_CPER_X86
262	bool
263	depends on UEFI_CPER && X86
264	default y
265
266config EFI_DEV_PATH_PARSER
267	bool
268	depends on ACPI
269	default n
270
271config EFI_EARLYCON
272	def_bool y
273	depends on SERIAL_EARLYCON && !ARM && !IA64
274	select FONT_SUPPORT
275	select ARCH_USE_MEMREMAP_PROT
276
277config EFI_CUSTOM_SSDT_OVERLAYS
278	bool "Load custom ACPI SSDT overlay from an EFI variable"
279	depends on EFI && ACPI
280	default ACPI_TABLE_UPGRADE
281	help
282	  Allow loading of an ACPI SSDT overlay from an EFI variable specified
283	  by a kernel command line option.
284
285	  See Documentation/admin-guide/acpi/ssdt-overlays.rst for more
286	  information.
287