1# SPDX-License-Identifier: GPL-2.0-only 2 3menu "Kexec and crash features" 4 5config CRASH_RESERVE 6 bool 7 8config VMCORE_INFO 9 bool 10 11config KEXEC_CORE 12 bool 13 14config KEXEC_ELF 15 bool 16 17config HAVE_IMA_KEXEC 18 bool 19 20config KEXEC 21 bool "Enable kexec system call" 22 depends on ARCH_SUPPORTS_KEXEC 23 select KEXEC_CORE 24 help 25 kexec is a system call that implements the ability to shutdown your 26 current kernel, and to start another kernel. It is like a reboot 27 but it is independent of the system firmware. And like a reboot 28 you can start any kernel with it, not just Linux. 29 30 The name comes from the similarity to the exec system call. 31 32 It is an ongoing process to be certain the hardware in a machine 33 is properly shutdown, so do not be surprised if this code does not 34 initially work for you. As of this writing the exact hardware 35 interface is strongly in flux, so no good recommendation can be 36 made. 37 38config KEXEC_FILE 39 bool "Enable kexec file based system call" 40 depends on ARCH_SUPPORTS_KEXEC_FILE 41 select CRYPTO_LIB_SHA256 42 select KEXEC_CORE 43 help 44 This is new version of kexec system call. This system call is 45 file based and takes file descriptors as system call argument 46 for kernel and initramfs as opposed to list of segments as 47 accepted by kexec system call. 48 49config KEXEC_SIG 50 bool "Verify kernel signature during kexec_file_load() syscall" 51 depends on ARCH_SUPPORTS_KEXEC_SIG 52 depends on KEXEC_FILE 53 help 54 This option makes the kexec_file_load() syscall check for a valid 55 signature of the kernel image. The image can still be loaded without 56 a valid signature unless you also enable KEXEC_SIG_FORCE, though if 57 there's a signature that we can check, then it must be valid. 58 59 In addition to this option, you need to enable signature 60 verification for the corresponding kernel image type being 61 loaded in order for this to work. 62 63config KEXEC_SIG_FORCE 64 bool "Require a valid signature in kexec_file_load() syscall" 65 depends on ARCH_SUPPORTS_KEXEC_SIG_FORCE 66 depends on KEXEC_SIG 67 help 68 This option makes kernel signature verification mandatory for 69 the kexec_file_load() syscall. 70 71config KEXEC_IMAGE_VERIFY_SIG 72 bool "Enable Image signature verification support (ARM)" 73 default ARCH_DEFAULT_KEXEC_IMAGE_VERIFY_SIG 74 depends on ARCH_SUPPORTS_KEXEC_IMAGE_VERIFY_SIG 75 depends on KEXEC_SIG 76 depends on EFI && SIGNED_PE_FILE_VERIFICATION 77 help 78 Enable Image signature verification support. 79 80config KEXEC_BZIMAGE_VERIFY_SIG 81 bool "Enable bzImage signature verification support" 82 depends on ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG 83 depends on KEXEC_SIG 84 depends on SIGNED_PE_FILE_VERIFICATION 85 select SYSTEM_TRUSTED_KEYRING 86 help 87 Enable bzImage signature verification support. 88 89config KEXEC_JUMP 90 bool "kexec jump" 91 depends on ARCH_SUPPORTS_KEXEC_JUMP 92 depends on KEXEC && HIBERNATION 93 help 94 Jump between original kernel and kexeced kernel and invoke 95 code in physical address mode via KEXEC 96 97config KEXEC_HANDOVER 98 bool "kexec handover" 99 depends on ARCH_SUPPORTS_KEXEC_HANDOVER && ARCH_SUPPORTS_KEXEC_FILE 100 depends on !DEFERRED_STRUCT_PAGE_INIT 101 select MEMBLOCK_KHO_SCRATCH 102 select KEXEC_FILE 103 select DEBUG_FS 104 select LIBFDT 105 select CMA 106 help 107 Allow kexec to hand over state across kernels by generating and 108 passing additional metadata to the target kernel. This is useful 109 to keep data or state alive across the kexec. For this to work, 110 both source and target kernels need to have this option enabled. 111 112config KEXEC_HANDOVER_DEBUG 113 bool "Enable Kexec Handover debug checks" 114 depends on KEXEC_HANDOVER 115 help 116 This option enables extra sanity checks for the Kexec Handover 117 subsystem. Since, KHO performance is crucial in live update 118 scenarios and the extra code might be adding overhead it is 119 only optionally enabled. 120 121config CRASH_DUMP 122 bool "kernel crash dumps" 123 default ARCH_DEFAULT_CRASH_DUMP 124 depends on ARCH_SUPPORTS_CRASH_DUMP 125 depends on KEXEC_CORE 126 select VMCORE_INFO 127 select CRASH_RESERVE 128 help 129 Generate crash dump after being started by kexec. 130 This should be normally only set in special crash dump kernels 131 which are loaded in the main kernel with kexec-tools into 132 a specially reserved region and then later executed after 133 a crash by kdump/kexec. The crash dump kernel must be compiled 134 to a memory address not used by the main kernel or BIOS using 135 PHYSICAL_START, or it must be built as a relocatable image 136 (CONFIG_RELOCATABLE=y). 137 For more details see Documentation/admin-guide/kdump/kdump.rst 138 139 For s390, this option also enables zfcpdump. 140 See also <file:Documentation/arch/s390/zfcpdump.rst> 141 142config CRASH_DM_CRYPT 143 bool "Support saving crash dump to dm-crypt encrypted volume" 144 depends on KEXEC_FILE 145 depends on CRASH_DUMP 146 depends on DM_CRYPT 147 depends on KEYS 148 help 149 With this option enabled, user space can intereact with 150 /sys/kernel/config/crash_dm_crypt_keys to make the dm crypt keys 151 persistent for the dump-capture kernel. 152 153config CRASH_DM_CRYPT_CONFIGS 154 def_tristate CRASH_DM_CRYPT 155 select CONFIGFS_FS 156 help 157 CRASH_DM_CRYPT cannot directly select CONFIGFS_FS, because that 158 is required to be built-in. 159 160config CRASH_DUMP_KUNIT_TEST 161 tristate "Unit Tests for kernel crash dumps" if !KUNIT_ALL_TESTS 162 depends on CRASH_DUMP && KUNIT 163 default KUNIT_ALL_TESTS 164 help 165 This option builds KUnit unit tests for kernel crash dumps. The unit 166 tests will be used to verify the correctness of covered functions and 167 also prevent any regression. 168 169 If unsure, say N. 170 171config CRASH_HOTPLUG 172 bool "Update the crash elfcorehdr on system configuration changes" 173 default y 174 depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG) 175 depends on ARCH_SUPPORTS_CRASH_HOTPLUG 176 help 177 Enable direct update to the crash elfcorehdr (which contains 178 the list of CPUs and memory regions to be dumped upon a crash) 179 in response to hot plug/unplug or online/offline of CPUs or 180 memory. This is a much more advanced approach than userspace 181 attempting that. 182 183 If unsure, say Y. 184 185config CRASH_MAX_MEMORY_RANGES 186 int "Specify the maximum number of memory regions for the elfcorehdr" 187 default 8192 188 depends on CRASH_HOTPLUG 189 help 190 For the kexec_file_load() syscall path, specify the maximum number of 191 memory regions that the elfcorehdr buffer/segment can accommodate. 192 These regions are obtained via walk_system_ram_res(); eg. the 193 'System RAM' entries in /proc/iomem. 194 This value is combined with NR_CPUS_DEFAULT and multiplied by 195 sizeof(Elf64_Phdr) to determine the final elfcorehdr memory buffer/ 196 segment size. 197 The value 8192, for example, covers a (sparsely populated) 1TiB system 198 consisting of 128MiB memblocks, while resulting in an elfcorehdr 199 memory buffer/segment size under 1MiB. This represents a sane choice 200 to accommodate both baremetal and virtual machine configurations. 201 202 For the kexec_load() syscall path, CRASH_MAX_MEMORY_RANGES is part of 203 the computation behind the value provided through the 204 /sys/kernel/crash_elfcorehdr_size attribute. 205 206endmenu 207