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