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_ARMSTUB_DTB_LOADER 109 bool "Enable the DTB loader" 110 depends on EFI_GENERIC_STUB && !RISCV 111 default y 112 help 113 Select this config option to add support for the dtb= command 114 line parameter, allowing a device tree blob to be loaded into 115 memory from the EFI System Partition by the stub. 116 117 If the device tree is provided by the platform or by 118 the bootloader this option may not be needed. 119 But, for various development reasons and to maintain existing 120 functionality for bootloaders that do not have such support 121 this option is necessary. 122 123config EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER 124 bool "Enable the command line initrd loader" if !X86 125 depends on EFI_STUB && (EFI_GENERIC_STUB || X86) 126 default y if X86 127 depends on !RISCV 128 help 129 Select this config option to add support for the initrd= command 130 line parameter, allowing an initrd that resides on the same volume 131 as the kernel image to be loaded into memory. 132 133 This method is deprecated. 134 135config EFI_BOOTLOADER_CONTROL 136 tristate "EFI Bootloader Control" 137 select UCS2_STRING 138 default n 139 help 140 This module installs a reboot hook, such that if reboot() is 141 invoked with a string argument NNN, "NNN" is copied to the 142 "LoaderEntryOneShot" EFI variable, to be read by the 143 bootloader. If the string matches one of the boot labels 144 defined in its configuration, the bootloader will boot once 145 to that label. The "LoaderEntryRebootReason" EFI variable is 146 set with the reboot reason: "reboot" or "shutdown". The 147 bootloader reads this reboot reason and takes particular 148 action according to its policy. 149 150config EFI_CAPSULE_LOADER 151 tristate "EFI capsule loader" 152 depends on EFI && !IA64 153 help 154 This option exposes a loader interface "/dev/efi_capsule_loader" for 155 users to load EFI capsules. This driver requires working runtime 156 capsule support in the firmware, which many OEMs do not provide. 157 158 Most users should say N. 159 160config EFI_CAPSULE_QUIRK_QUARK_CSH 161 bool "Add support for Quark capsules with non-standard headers" 162 depends on X86 && !64BIT 163 select EFI_CAPSULE_LOADER 164 default y 165 help 166 Add support for processing Quark X1000 EFI capsules, whose header 167 layout deviates from the layout mandated by the UEFI specification. 168 169config EFI_TEST 170 tristate "EFI Runtime Service Tests Support" 171 depends on EFI 172 default n 173 help 174 This driver uses the efi.<service> function pointers directly instead 175 of going through the efivar API, because it is not trying to test the 176 kernel subsystem, just for testing the UEFI runtime service 177 interfaces which are provided by the firmware. This driver is used 178 by the Firmware Test Suite (FWTS) for testing the UEFI runtime 179 interfaces readiness of the firmware. 180 Details for FWTS are available from: 181 <https://wiki.ubuntu.com/FirmwareTestSuite> 182 183 Say Y here to enable the runtime services support via /dev/efi_test. 184 If unsure, say N. 185 186config EFI_DEV_PATH_PARSER 187 bool 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 251config EFI_EARLYCON 252 def_bool y 253 depends on SERIAL_EARLYCON && !ARM && !IA64 254 select FONT_SUPPORT 255 select ARCH_USE_MEMREMAP_PROT 256 257config EFI_CUSTOM_SSDT_OVERLAYS 258 bool "Load custom ACPI SSDT overlay from an EFI variable" 259 depends on ACPI 260 default ACPI_TABLE_UPGRADE 261 help 262 Allow loading of an ACPI SSDT overlay from an EFI variable specified 263 by a kernel command line option. 264 265 See Documentation/admin-guide/acpi/ssdt-overlays.rst for more 266 information. 267 268config EFI_DISABLE_RUNTIME 269 bool "Disable EFI runtime services support by default" 270 default y if PREEMPT_RT 271 help 272 Allow to disable the EFI runtime services support by default. This can 273 already be achieved by using the efi=noruntime option, but it could be 274 useful to have this default without any kernel command line parameter. 275 276 The EFI runtime services are disabled by default when PREEMPT_RT is 277 enabled, because measurements have shown that some EFI functions calls 278 might take too much time to complete, causing large latencies which is 279 an issue for Real-Time kernels. 280 281 This default can be overridden by using the efi=runtime option. 282 283config EFI_COCO_SECRET 284 bool "EFI Confidential Computing Secret Area Support" 285 help 286 Confidential Computing platforms (such as AMD SEV) allow the 287 Guest Owner to securely inject secrets during guest VM launch. 288 The secrets are placed in a designated EFI reserved memory area. 289 290 In order to use the secrets in the kernel, the location of the secret 291 area (as published in the EFI config table) must be kept. 292 293 If you say Y here, the address of the EFI secret area will be kept 294 for usage inside the kernel. This will allow the 295 virt/coco/efi_secret module to access the secrets, which in turn 296 allows userspace programs to access the injected secrets. 297 298config EFI_EMBEDDED_FIRMWARE 299 bool 300 select CRYPTO_LIB_SHA256 301 302endmenu 303 304config UEFI_CPER 305 bool 306 307config UEFI_CPER_ARM 308 bool 309 depends on UEFI_CPER && ( ARM || ARM64 ) 310 default y 311 312config UEFI_CPER_X86 313 bool 314 depends on UEFI_CPER && X86 315 default y 316