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 CRASH_DUMP 113 bool "kernel crash dumps" 114 default ARCH_DEFAULT_CRASH_DUMP 115 depends on ARCH_SUPPORTS_CRASH_DUMP 116 depends on KEXEC_CORE 117 select VMCORE_INFO 118 select CRASH_RESERVE 119 help 120 Generate crash dump after being started by kexec. 121 This should be normally only set in special crash dump kernels 122 which are loaded in the main kernel with kexec-tools into 123 a specially reserved region and then later executed after 124 a crash by kdump/kexec. The crash dump kernel must be compiled 125 to a memory address not used by the main kernel or BIOS using 126 PHYSICAL_START, or it must be built as a relocatable image 127 (CONFIG_RELOCATABLE=y). 128 For more details see Documentation/admin-guide/kdump/kdump.rst 129 130 For s390, this option also enables zfcpdump. 131 See also <file:Documentation/arch/s390/zfcpdump.rst> 132 133config CRASH_DM_CRYPT 134 bool "Support saving crash dump to dm-crypt encrypted volume" 135 depends on KEXEC_FILE 136 depends on CRASH_DUMP 137 depends on DM_CRYPT 138 depends on KEYS 139 help 140 With this option enabled, user space can intereact with 141 /sys/kernel/config/crash_dm_crypt_keys to make the dm crypt keys 142 persistent for the dump-capture kernel. 143 144config CRASH_DM_CRYPT_CONFIGS 145 def_tristate CRASH_DM_CRYPT 146 select CONFIGFS_FS 147 help 148 CRASH_DM_CRYPT cannot directly select CONFIGFS_FS, because that 149 is required to be built-in. 150 151config CRASH_HOTPLUG 152 bool "Update the crash elfcorehdr on system configuration changes" 153 default y 154 depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG) 155 depends on ARCH_SUPPORTS_CRASH_HOTPLUG 156 help 157 Enable direct update to the crash elfcorehdr (which contains 158 the list of CPUs and memory regions to be dumped upon a crash) 159 in response to hot plug/unplug or online/offline of CPUs or 160 memory. This is a much more advanced approach than userspace 161 attempting that. 162 163 If unsure, say Y. 164 165config CRASH_MAX_MEMORY_RANGES 166 int "Specify the maximum number of memory regions for the elfcorehdr" 167 default 8192 168 depends on CRASH_HOTPLUG 169 help 170 For the kexec_file_load() syscall path, specify the maximum number of 171 memory regions that the elfcorehdr buffer/segment can accommodate. 172 These regions are obtained via walk_system_ram_res(); eg. the 173 'System RAM' entries in /proc/iomem. 174 This value is combined with NR_CPUS_DEFAULT and multiplied by 175 sizeof(Elf64_Phdr) to determine the final elfcorehdr memory buffer/ 176 segment size. 177 The value 8192, for example, covers a (sparsely populated) 1TiB system 178 consisting of 128MiB memblocks, while resulting in an elfcorehdr 179 memory buffer/segment size under 1MiB. This represents a sane choice 180 to accommodate both baremetal and virtual machine configurations. 181 182 For the kexec_load() syscall path, CRASH_MAX_MEMORY_RANGES is part of 183 the computation behind the value provided through the 184 /sys/kernel/crash_elfcorehdr_size attribute. 185 186endmenu 187