1# SPDX-License-Identifier: GPL-2.0-only 2menu "EFI (Extensible Firmware Interface) Support" 3 depends on EFI 4 5config EFI_ESRT 6 bool 7 depends on EFI && !IA64 8 default y 9 10config EFI_VARS_PSTORE 11 tristate "Register efivars backend for pstore" 12 depends on PSTORE 13 select UCS2_STRING 14 default y 15 help 16 Say Y here to enable use efivars as a backend to pstore. This 17 will allow writing console messages, crash dumps, or anything 18 else supported by pstore to EFI variables. 19 20config EFI_VARS_PSTORE_DEFAULT_DISABLE 21 bool "Disable using efivars as a pstore backend by default" 22 depends on EFI_VARS_PSTORE 23 default n 24 help 25 Saying Y here will disable the use of efivars as a storage 26 backend for pstore by default. This setting can be overridden 27 using the efivars module's pstore_disable parameter. 28 29config EFI_RUNTIME_MAP 30 bool "Export efi runtime maps to sysfs" 31 depends on X86 && EFI && KEXEC_CORE 32 default y 33 help 34 Export efi runtime memory maps to /sys/firmware/efi/runtime-map. 35 That memory map is used for example by kexec to set up efi virtual 36 mapping the 2nd kernel, but can also be used for debugging purposes. 37 38 See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map. 39 40config EFI_FAKE_MEMMAP 41 bool "Enable EFI fake memory map" 42 depends on EFI && X86 43 default n 44 help 45 Saying Y here will enable "efi_fake_mem" boot option. 46 By specifying this parameter, you can add arbitrary attribute 47 to specific memory range by updating original (firmware provided) 48 EFI memmap. 49 This is useful for debugging of EFI memmap related feature. 50 e.g. Address Range Mirroring feature. 51 52config EFI_MAX_FAKE_MEM 53 int "maximum allowable number of ranges in efi_fake_mem boot option" 54 depends on EFI_FAKE_MEMMAP 55 range 1 128 56 default 8 57 help 58 Maximum allowable number of ranges in efi_fake_mem boot option. 59 Ranges can be set up to this value using comma-separated list. 60 The default value is 8. 61 62config EFI_SOFT_RESERVE 63 bool "Reserve EFI Specific Purpose Memory" 64 depends on EFI && EFI_STUB && ACPI_HMAT 65 default ACPI_HMAT 66 help 67 On systems that have mixed performance classes of memory EFI 68 may indicate specific purpose memory with an attribute (See 69 EFI_MEMORY_SP in UEFI 2.8). A memory range tagged with this 70 attribute may have unique performance characteristics compared 71 to the system's general purpose "System RAM" pool. On the 72 expectation that such memory has application specific usage, 73 and its base EFI memory type is "conventional" answer Y to 74 arrange for the kernel to reserve it as a "Soft Reserved" 75 resource, and set aside for direct-access (device-dax) by 76 default. The memory range can later be optionally assigned to 77 the page allocator by system administrator policy via the 78 device-dax kmem facility. Say N to have the kernel treat this 79 memory as "System RAM" by default. 80 81 If unsure, say Y. 82 83config EFI_DXE_MEM_ATTRIBUTES 84 bool "Adjust memory attributes in EFISTUB" 85 depends on EFI && EFI_STUB && X86 86 default y 87 help 88 UEFI specification does not guarantee all memory to be 89 accessible for both write and execute as the kernel expects 90 it to be. 91 Use DXE services to check and alter memory protection 92 attributes during boot via EFISTUB to ensure that memory 93 ranges used by the kernel are writable and executable. 94 95config EFI_PARAMS_FROM_FDT 96 bool 97 help 98 Select this config option from the architecture Kconfig if 99 the EFI runtime support gets system table address, memory 100 map address, and other parameters from the device tree. 101 102config EFI_RUNTIME_WRAPPERS 103 bool 104 105config EFI_GENERIC_STUB 106 bool 107 108config EFI_ZBOOT 109 bool "Enable the generic EFI decompressor" 110 depends on EFI_GENERIC_STUB && !ARM 111 select HAVE_KERNEL_GZIP 112 select HAVE_KERNEL_LZ4 113 select HAVE_KERNEL_LZMA 114 select HAVE_KERNEL_LZO 115 select HAVE_KERNEL_XZ 116 select HAVE_KERNEL_ZSTD 117 help 118 Create the bootable image as an EFI application that carries the 119 actual kernel image in compressed form, and decompresses it into 120 memory before executing it via LoadImage/StartImage EFI boot service 121 calls. For compatibility with non-EFI loaders, the payload can be 122 decompressed and executed by the loader as well, provided that the 123 loader implements the decompression algorithm and that non-EFI boot 124 is supported by the encapsulated image. (The compression algorithm 125 used is described in the zboot image header) 126 127config EFI_ARMSTUB_DTB_LOADER 128 bool "Enable the DTB loader" 129 depends on EFI_GENERIC_STUB && !RISCV && !LOONGARCH 130 default y 131 help 132 Select this config option to add support for the dtb= command 133 line parameter, allowing a device tree blob to be loaded into 134 memory from the EFI System Partition by the stub. 135 136 If the device tree is provided by the platform or by 137 the bootloader this option may not be needed. 138 But, for various development reasons and to maintain existing 139 functionality for bootloaders that do not have such support 140 this option is necessary. 141 142config EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER 143 bool "Enable the command line initrd loader" if !X86 144 depends on EFI_STUB && (EFI_GENERIC_STUB || X86) 145 default y if X86 146 depends on !RISCV && !LOONGARCH 147 help 148 Select this config option to add support for the initrd= command 149 line parameter, allowing an initrd that resides on the same volume 150 as the kernel image to be loaded into memory. 151 152 This method is deprecated. 153 154config EFI_BOOTLOADER_CONTROL 155 tristate "EFI Bootloader Control" 156 select UCS2_STRING 157 default n 158 help 159 This module installs a reboot hook, such that if reboot() is 160 invoked with a string argument NNN, "NNN" is copied to the 161 "LoaderEntryOneShot" EFI variable, to be read by the 162 bootloader. If the string matches one of the boot labels 163 defined in its configuration, the bootloader will boot once 164 to that label. The "LoaderEntryRebootReason" EFI variable is 165 set with the reboot reason: "reboot" or "shutdown". The 166 bootloader reads this reboot reason and takes particular 167 action according to its policy. 168 169config EFI_CAPSULE_LOADER 170 tristate "EFI capsule loader" 171 depends on EFI && !IA64 172 help 173 This option exposes a loader interface "/dev/efi_capsule_loader" for 174 users to load EFI capsules. This driver requires working runtime 175 capsule support in the firmware, which many OEMs do not provide. 176 177 Most users should say N. 178 179config EFI_CAPSULE_QUIRK_QUARK_CSH 180 bool "Add support for Quark capsules with non-standard headers" 181 depends on X86 && !64BIT 182 select EFI_CAPSULE_LOADER 183 default y 184 help 185 Add support for processing Quark X1000 EFI capsules, whose header 186 layout deviates from the layout mandated by the UEFI specification. 187 188config EFI_TEST 189 tristate "EFI Runtime Service Tests Support" 190 depends on EFI 191 default n 192 help 193 This driver uses the efi.<service> function pointers directly instead 194 of going through the efivar API, because it is not trying to test the 195 kernel subsystem, just for testing the UEFI runtime service 196 interfaces which are provided by the firmware. This driver is used 197 by the Firmware Test Suite (FWTS) for testing the UEFI runtime 198 interfaces readiness of the firmware. 199 Details for FWTS are available from: 200 <https://wiki.ubuntu.com/FirmwareTestSuite> 201 202 Say Y here to enable the runtime services support via /dev/efi_test. 203 If unsure, say N. 204 205config EFI_DEV_PATH_PARSER 206 bool 207 208config APPLE_PROPERTIES 209 bool "Apple Device Properties" 210 depends on EFI_STUB && X86 211 select EFI_DEV_PATH_PARSER 212 select UCS2_STRING 213 help 214 Retrieve properties from EFI on Apple Macs and assign them to 215 devices, allowing for improved support of Apple hardware. 216 Properties that would otherwise be missing include the 217 Thunderbolt Device ROM and GPU configuration data. 218 219 If unsure, say Y if you have a Mac. Otherwise N. 220 221config RESET_ATTACK_MITIGATION 222 bool "Reset memory attack mitigation" 223 depends on EFI_STUB 224 help 225 Request that the firmware clear the contents of RAM after a reboot 226 using the TCG Platform Reset Attack Mitigation specification. This 227 protects against an attacker forcibly rebooting the system while it 228 still contains secrets in RAM, booting another OS and extracting the 229 secrets. This should only be enabled when userland is configured to 230 clear the MemoryOverwriteRequest flag on clean shutdown after secrets 231 have been evicted, since otherwise it will trigger even on clean 232 reboots. 233 234config EFI_RCI2_TABLE 235 bool "EFI Runtime Configuration Interface Table Version 2 Support" 236 depends on X86 || COMPILE_TEST 237 help 238 Displays the content of the Runtime Configuration Interface 239 Table version 2 on Dell EMC PowerEdge systems as a binary 240 attribute 'rci2' under /sys/firmware/efi/tables directory. 241 242 RCI2 table contains BIOS HII in XML format and is used to populate 243 BIOS setup page in Dell EMC OpenManage Server Administrator tool. 244 The BIOS setup page contains BIOS tokens which can be configured. 245 246 Say Y here for Dell EMC PowerEdge systems. 247 248config EFI_DISABLE_PCI_DMA 249 bool "Clear Busmaster bit on PCI bridges during ExitBootServices()" 250 help 251 Disable the busmaster bit in the control register on all PCI bridges 252 while calling ExitBootServices() and passing control to the runtime 253 kernel. System firmware may configure the IOMMU to prevent malicious 254 PCI devices from being able to attack the OS via DMA. However, since 255 firmware can't guarantee that the OS is IOMMU-aware, it will tear 256 down IOMMU configuration when ExitBootServices() is called. This 257 leaves a window between where a hostile device could still cause 258 damage before Linux configures the IOMMU again. 259 260 If you say Y here, the EFI stub will clear the busmaster bit on all 261 PCI bridges before ExitBootServices() is called. This will prevent 262 any malicious PCI devices from being able to perform DMA until the 263 kernel reenables busmastering after configuring the IOMMU. 264 265 This option will cause failures with some poorly behaved hardware 266 and should not be enabled without testing. The kernel commandline 267 options "efi=disable_early_pci_dma" or "efi=no_disable_early_pci_dma" 268 may be used to override this option. 269 270config EFI_EARLYCON 271 def_bool y 272 depends on SERIAL_EARLYCON && !ARM && !IA64 273 select FONT_SUPPORT 274 select ARCH_USE_MEMREMAP_PROT 275 276config EFI_CUSTOM_SSDT_OVERLAYS 277 bool "Load custom ACPI SSDT overlay from an EFI variable" 278 depends on ACPI 279 default ACPI_TABLE_UPGRADE 280 help 281 Allow loading of an ACPI SSDT overlay from an EFI variable specified 282 by a kernel command line option. 283 284 See Documentation/admin-guide/acpi/ssdt-overlays.rst for more 285 information. 286 287config EFI_DISABLE_RUNTIME 288 bool "Disable EFI runtime services support by default" 289 default y if PREEMPT_RT 290 help 291 Allow to disable the EFI runtime services support by default. This can 292 already be achieved by using the efi=noruntime option, but it could be 293 useful to have this default without any kernel command line parameter. 294 295 The EFI runtime services are disabled by default when PREEMPT_RT is 296 enabled, because measurements have shown that some EFI functions calls 297 might take too much time to complete, causing large latencies which is 298 an issue for Real-Time kernels. 299 300 This default can be overridden by using the efi=runtime option. 301 302config EFI_COCO_SECRET 303 bool "EFI Confidential Computing Secret Area Support" 304 help 305 Confidential Computing platforms (such as AMD SEV) allow the 306 Guest Owner to securely inject secrets during guest VM launch. 307 The secrets are placed in a designated EFI reserved memory area. 308 309 In order to use the secrets in the kernel, the location of the secret 310 area (as published in the EFI config table) must be kept. 311 312 If you say Y here, the address of the EFI secret area will be kept 313 for usage inside the kernel. This will allow the 314 virt/coco/efi_secret module to access the secrets, which in turn 315 allows userspace programs to access the injected secrets. 316 317config EFI_EMBEDDED_FIRMWARE 318 bool 319 select CRYPTO_LIB_SHA256 320 321endmenu 322 323config UEFI_CPER 324 bool 325 326config UEFI_CPER_ARM 327 bool 328 depends on UEFI_CPER && ( ARM || ARM64 ) 329 default y 330 331config UEFI_CPER_X86 332 bool 333 depends on UEFI_CPER && X86 334 default y 335