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_ARMSTUB 110 bool 111 112config EFI_ARMSTUB_DTB_LOADER 113 bool "Enable the DTB loader" 114 depends on EFI_ARMSTUB 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_BOOTLOADER_CONTROL 128 tristate "EFI Bootloader Control" 129 depends on EFI_VARS 130 default n 131 ---help--- 132 This module installs a reboot hook, such that if reboot() is 133 invoked with a string argument NNN, "NNN" is copied to the 134 "LoaderEntryOneShot" EFI variable, to be read by the 135 bootloader. If the string matches one of the boot labels 136 defined in its configuration, the bootloader will boot once 137 to that label. The "LoaderEntryRebootReason" EFI variable is 138 set with the reboot reason: "reboot" or "shutdown". The 139 bootloader reads this reboot reason and takes particular 140 action according to its policy. 141 142config EFI_CAPSULE_LOADER 143 tristate "EFI capsule loader" 144 depends on EFI 145 help 146 This option exposes a loader interface "/dev/efi_capsule_loader" for 147 users to load EFI capsules. This driver requires working runtime 148 capsule support in the firmware, which many OEMs do not provide. 149 150 Most users should say N. 151 152config EFI_CAPSULE_QUIRK_QUARK_CSH 153 bool "Add support for Quark capsules with non-standard headers" 154 depends on X86 && !64BIT 155 select EFI_CAPSULE_LOADER 156 default y 157 help 158 Add support for processing Quark X1000 EFI capsules, whose header 159 layout deviates from the layout mandated by the UEFI specification. 160 161config EFI_TEST 162 tristate "EFI Runtime Service Tests Support" 163 depends on EFI 164 default n 165 help 166 This driver uses the efi.<service> function pointers directly instead 167 of going through the efivar API, because it is not trying to test the 168 kernel subsystem, just for testing the UEFI runtime service 169 interfaces which are provided by the firmware. This driver is used 170 by the Firmware Test Suite (FWTS) for testing the UEFI runtime 171 interfaces readiness of the firmware. 172 Details for FWTS are available from: 173 <https://wiki.ubuntu.com/FirmwareTestSuite> 174 175 Say Y here to enable the runtime services support via /dev/efi_test. 176 If unsure, say N. 177 178config APPLE_PROPERTIES 179 bool "Apple Device Properties" 180 depends on EFI_STUB && X86 181 select EFI_DEV_PATH_PARSER 182 select UCS2_STRING 183 help 184 Retrieve properties from EFI on Apple Macs and assign them to 185 devices, allowing for improved support of Apple hardware. 186 Properties that would otherwise be missing include the 187 Thunderbolt Device ROM and GPU configuration data. 188 189 If unsure, say Y if you have a Mac. Otherwise N. 190 191config RESET_ATTACK_MITIGATION 192 bool "Reset memory attack mitigation" 193 depends on EFI_STUB 194 help 195 Request that the firmware clear the contents of RAM after a reboot 196 using the TCG Platform Reset Attack Mitigation specification. This 197 protects against an attacker forcibly rebooting the system while it 198 still contains secrets in RAM, booting another OS and extracting the 199 secrets. This should only be enabled when userland is configured to 200 clear the MemoryOverwriteRequest flag on clean shutdown after secrets 201 have been evicted, since otherwise it will trigger even on clean 202 reboots. 203 204config EFI_RCI2_TABLE 205 bool "EFI Runtime Configuration Interface Table Version 2 Support" 206 depends on X86 || COMPILE_TEST 207 help 208 Displays the content of the Runtime Configuration Interface 209 Table version 2 on Dell EMC PowerEdge systems as a binary 210 attribute 'rci2' under /sys/firmware/efi/tables directory. 211 212 RCI2 table contains BIOS HII in XML format and is used to populate 213 BIOS setup page in Dell EMC OpenManage Server Administrator tool. 214 The BIOS setup page contains BIOS tokens which can be configured. 215 216 Say Y here for Dell EMC PowerEdge systems. 217 218config EFI_DISABLE_PCI_DMA 219 bool "Clear Busmaster bit on PCI bridges during ExitBootServices()" 220 help 221 Disable the busmaster bit in the control register on all PCI bridges 222 while calling ExitBootServices() and passing control to the runtime 223 kernel. System firmware may configure the IOMMU to prevent malicious 224 PCI devices from being able to attack the OS via DMA. However, since 225 firmware can't guarantee that the OS is IOMMU-aware, it will tear 226 down IOMMU configuration when ExitBootServices() is called. This 227 leaves a window between where a hostile device could still cause 228 damage before Linux configures the IOMMU again. 229 230 If you say Y here, the EFI stub will clear the busmaster bit on all 231 PCI bridges before ExitBootServices() is called. This will prevent 232 any malicious PCI devices from being able to perform DMA until the 233 kernel reenables busmastering after configuring the IOMMU. 234 235 This option will cause failures with some poorly behaved hardware 236 and should not be enabled without testing. The kernel commandline 237 options "efi=disable_early_pci_dma" or "efi=no_disable_early_pci_dma" 238 may be used to override this option. 239 240endmenu 241 242config EFI_EMBEDDED_FIRMWARE 243 bool 244 depends on EFI 245 select CRYPTO_LIB_SHA256 246 247config UEFI_CPER 248 bool 249 250config UEFI_CPER_ARM 251 bool 252 depends on UEFI_CPER && ( ARM || ARM64 ) 253 default y 254 255config UEFI_CPER_X86 256 bool 257 depends on UEFI_CPER && X86 258 default y 259 260config EFI_DEV_PATH_PARSER 261 bool 262 depends on ACPI 263 default n 264 265config EFI_EARLYCON 266 def_bool y 267 depends on SERIAL_EARLYCON && !ARM && !IA64 268 select FONT_SUPPORT 269 select ARCH_USE_MEMREMAP_PROT 270