kernel/Kconfig.kexec

   1 # SPDX-License-Identifier: GPL-2.0-only
   2
   3 menu "Kexec and crash features"
   4
   5 config CRASH_CORE
   6         bool
   7
   8 config KEXEC_CORE
   9         select CRASH_CORE
  10         bool
  11
  12 config KEXEC_ELF
  13         bool
  14
  15 config HAVE_IMA_KEXEC
  16         bool
  17
  18 config KEXEC
  19         bool "Enable kexec system call"
  20         depends on ARCH_SUPPORTS_KEXEC
  21         select KEXEC_CORE
  22         help
  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.
  27
  28           The name comes from the similarity to the exec system call.
  29
  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
  34           made.
  35
  36 config KEXEC_FILE
  37         bool "Enable kexec file based system call"
  38         depends on ARCH_SUPPORTS_KEXEC_FILE
  39         select KEXEC_CORE
  40         help
  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.
  45
  46 config KEXEC_SIG
  47         bool "Verify kernel signature during kexec_file_load() syscall"
  48         depends on ARCH_SUPPORTS_KEXEC_SIG
  49         depends on KEXEC_FILE
  50         help
  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.
  55
  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.
  59
  60 config KEXEC_SIG_FORCE
  61         bool "Require a valid signature in kexec_file_load() syscall"
  62         depends on ARCH_SUPPORTS_KEXEC_SIG_FORCE
  63         depends on KEXEC_SIG
  64         help
  65           This option makes kernel signature verification mandatory for
  66           the kexec_file_load() syscall.
  67
  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
  72         depends on KEXEC_SIG
  73         depends on EFI && SIGNED_PE_FILE_VERIFICATION
  74         help
  75           Enable Image signature verification support.
  76
  77 config KEXEC_BZIMAGE_VERIFY_SIG
  78         bool "Enable bzImage signature verification support"
  79         depends on ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
  80         depends on KEXEC_SIG
  81         depends on SIGNED_PE_FILE_VERIFICATION
  82         select SYSTEM_TRUSTED_KEYRING
  83         help
  84           Enable bzImage signature verification support.
  85
  86 config KEXEC_JUMP
  87         bool "kexec jump"
  88         depends on ARCH_SUPPORTS_KEXEC_JUMP
  89         depends on KEXEC && HIBERNATION
  90         help
  91           Jump between original kernel and kexeced kernel and invoke
  92           code in physical address mode via KEXEC
  93
  94 config CRASH_DUMP
  95         bool "kernel crash dumps"
  96         depends on ARCH_SUPPORTS_CRASH_DUMP
  97         select CRASH_CORE
  98         select KEXEC_CORE
  99         help
 100           Generate crash dump after being started by kexec.
 101           This should be normally only set in special crash dump kernels
 102           which are loaded in the main kernel with kexec-tools into
 103           a specially reserved region and then later executed after
 104           a crash by kdump/kexec. The crash dump kernel must be compiled
 105           to a memory address not used by the main kernel or BIOS using
 106           PHYSICAL_START, or it must be built as a relocatable image
 107           (CONFIG_RELOCATABLE=y).
 108           For more details see Documentation/admin-guide/kdump/kdump.rst
 109
 110           For s390, this option also enables zfcpdump.
 111           See also <file:Documentation/arch/s390/zfcpdump.rst>
 112
 113 config CRASH_HOTPLUG
 114         bool "Update the crash elfcorehdr on system configuration changes"
 115         default y
 116         depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG)
 117         depends on ARCH_SUPPORTS_CRASH_HOTPLUG
 118         help
 119           Enable direct update to the crash elfcorehdr (which contains
 120           the list of CPUs and memory regions to be dumped upon a crash)
 121           in response to hot plug/unplug or online/offline of CPUs or
 122           memory. This is a much more advanced approach than userspace
 123           attempting that.
 124
 125           If unsure, say Y.
 126
 127 config CRASH_MAX_MEMORY_RANGES
 128         int "Specify the maximum number of memory regions for the elfcorehdr"
 129         default 8192
 130         depends on CRASH_HOTPLUG
 131         help
 132           For the kexec_file_load() syscall path, specify the maximum number of
 133           memory regions that the elfcorehdr buffer/segment can accommodate.
 134           These regions are obtained via walk_system_ram_res(); eg. the
 135           'System RAM' entries in /proc/iomem.
 136           This value is combined with NR_CPUS_DEFAULT and multiplied by
 137           sizeof(Elf64_Phdr) to determine the final elfcorehdr memory buffer/
 138           segment size.
 139           The value 8192, for example, covers a (sparsely populated) 1TiB system
 140           consisting of 128MiB memblocks, while resulting in an elfcorehdr
 141           memory buffer/segment size under 1MiB. This represents a sane choice
 142           to accommodate both baremetal and virtual machine configurations.
 143
 144           For the kexec_load() syscall path, CRASH_MAX_MEMORY_RANGES is part of
 145           the computation behind the value provided through the
 146           /sys/kernel/crash_elfcorehdr_size attribute.
 147
 148 endmenu