1 # SPDX-License-Identifier: GPL-2.0-only
3 menu "Kexec and crash features"
19 bool "Enable kexec system call"
20 depends on ARCH_SUPPORTS_KEXEC
23 kexec is a system call that implements the ability to shutdown your
24 current kernel, and to start another kernel. It is like a reboot
25 but it is independent of the system firmware. And like a reboot
26 you can start any kernel with it, not just Linux.
28 The name comes from the similarity to the exec system call.
30 It is an ongoing process to be certain the hardware in a machine
31 is properly shutdown, so do not be surprised if this code does not
32 initially work for you. As of this writing the exact hardware
33 interface is strongly in flux, so no good recommendation can be
37 bool "Enable kexec file based system call"
38 depends on ARCH_SUPPORTS_KEXEC_FILE
41 This is new version of kexec system call. This system call is
42 file based and takes file descriptors as system call argument
43 for kernel and initramfs as opposed to list of segments as
44 accepted by kexec system call.
47 bool "Verify kernel signature during kexec_file_load() syscall"
48 depends on ARCH_SUPPORTS_KEXEC_SIG
51 This option makes the kexec_file_load() syscall check for a valid
52 signature of the kernel image. The image can still be loaded without
53 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
54 there's a signature that we can check, then it must be valid.
56 In addition to this option, you need to enable signature
57 verification for the corresponding kernel image type being
58 loaded in order for this to work.
60 config KEXEC_SIG_FORCE
61 bool "Require a valid signature in kexec_file_load() syscall"
62 depends on ARCH_SUPPORTS_KEXEC_SIG_FORCE
65 This option makes kernel signature verification mandatory for
66 the kexec_file_load() syscall.
68 config KEXEC_IMAGE_VERIFY_SIG
69 bool "Enable Image signature verification support (ARM)"
70 default ARCH_DEFAULT_KEXEC_IMAGE_VERIFY_SIG
71 depends on ARCH_SUPPORTS_KEXEC_IMAGE_VERIFY_SIG
73 depends on EFI && SIGNED_PE_FILE_VERIFICATION
75 Enable Image signature verification support.
77 config KEXEC_BZIMAGE_VERIFY_SIG
78 bool "Enable bzImage signature verification support"
79 depends on ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
81 depends on SIGNED_PE_FILE_VERIFICATION
82 select SYSTEM_TRUSTED_KEYRING
84 Enable bzImage signature verification support.
88 depends on ARCH_SUPPORTS_KEXEC_JUMP
89 depends on KEXEC && HIBERNATION
91 Jump between original kernel and kexeced kernel and invoke
92 code in physical address mode via KEXEC
95 bool "kernel crash dumps"
96 depends on ARCH_SUPPORTS_CRASH_DUMP
97 depends on ARCH_SUPPORTS_KEXEC
101 Generate crash dump after being started by kexec.
102 This should be normally only set in special crash dump kernels
103 which are loaded in the main kernel with kexec-tools into
104 a specially reserved region and then later executed after
105 a crash by kdump/kexec. The crash dump kernel must be compiled
106 to a memory address not used by the main kernel or BIOS using
107 PHYSICAL_START, or it must be built as a relocatable image
108 (CONFIG_RELOCATABLE=y).
109 For more details see Documentation/admin-guide/kdump/kdump.rst
111 For s390, this option also enables zfcpdump.
112 See also <file:Documentation/s390/zfcpdump.rst>
115 bool "Update the crash elfcorehdr on system configuration changes"
117 depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG)
118 depends on ARCH_SUPPORTS_CRASH_HOTPLUG
120 Enable direct update to the crash elfcorehdr (which contains
121 the list of CPUs and memory regions to be dumped upon a crash)
122 in response to hot plug/unplug or online/offline of CPUs or
123 memory. This is a much more advanced approach than userspace
128 config CRASH_MAX_MEMORY_RANGES
129 int "Specify the maximum number of memory regions for the elfcorehdr"
131 depends on CRASH_HOTPLUG
133 For the kexec_file_load() syscall path, specify the maximum number of
134 memory regions that the elfcorehdr buffer/segment can accommodate.
135 These regions are obtained via walk_system_ram_res(); eg. the
136 'System RAM' entries in /proc/iomem.
137 This value is combined with NR_CPUS_DEFAULT and multiplied by
138 sizeof(Elf64_Phdr) to determine the final elfcorehdr memory buffer/
140 The value 8192, for example, covers a (sparsely populated) 1TiB system
141 consisting of 128MiB memblocks, while resulting in an elfcorehdr
142 memory buffer/segment size under 1MiB. This represents a sane choice
143 to accommodate both baremetal and virtual machine configurations.
145 For the kexec_load() syscall path, CRASH_MAX_MEMORY_RANGES is part of
146 the computation behind the value provided through the
147 /sys/kernel/crash_elfcorehdr_size attribute.