man2/kexec_load.2

   1 .TH KEXEC_LOAD 2 2010-06-16 "Linux" "Linux Programmer's Manual"
   2 .SH NAME
   3 kexec_load \- Load a new kernel for later execution.
   4 .SH SYNOPSIS
   5 .b #include <linux/kexec.h>
   6 .br
   7 .BI "long kexec_load(unsigned long " entry ", unsigned long " nr_segments ","
   8 .br
   9 .BI       "struct kexec_segment *" segments ", unsigned long " flags ");"
  10 .SH DESCRIPTION
  11 .BR kexec_load
  12 loads a new kernel that can be executed later
  13 by
  14 .I reboot(2).
  15 An alternative approach is to specify
  16 .B KEXEC_ON_CRASH
  17 in the
  18 .I flags
  19 argument and then the new kernel will be automatically executed on a
  20 system crash.
  21 .\" XXX figure out how this is really used
  22 With
  23 .B KEXEC_PRESERVE_CONTEXT
  24 specified in
  25 .I flags
  26 kexec will preserve the system hard and
  27 software state before executing the kexec kernel. This
  28 could be used for system suspend.
  29
  30 .I flags
  31 also contains the architecture of the executed kernel or
  32 be
  33 .I KEXEC_ARCH_DEFAULT
  34 for the current architecture.
  35 Valid architectures are
  36 .I KEXEC_ARCH_I386,
  37 .I KEXEC_ARCH_X86_64,
  38 .I KEXEC_ARCH_PPC,
  39 .I KEXEC_ARCH_PPC64,
  40 .I KEXEC_ARCH_IA_64,
  41 .I KEXEC_ARCH_ARM,
  42 .I KEXEC_ARCH_S390,
  43 .I KEXEC_ARCH_SH,
  44 .I KEXEC_ARCH_MIPS,
  45 .I KEXEC_ARCH_MIPS_LE.
  46 The architecture must be executable on the CPU of the system.
  47
  48 .I entry
  49 is the virtual entry address in the kernel image.
  50 .I nr_segments
  51 is the number of segments pointed to by the
  52 .I segments
  53 pointer.
  54 .I segments
  55 is an array of
  56 .I struct kexec_segment
  57 structures which define the kernel layout:
  58 .in +4n
  59 .nf
  60
  61 struct kexec_segment {
  62         void   *buf;    /* Buffer in user space */
  63         size_t  bufsz;  /* Buffer length in user space */
  64         void   *mem;    /* Virtual address of kernel */
  65         size_t  memsz;  /* Virtual address length */
  66 };
  67 .fi
  68 .in
  69 .PP
  70 .\" XXX elaborate on this
  71 The kernel image defined by
  72 .I segments
  73 is copied from the calling process into previously reserved memory.
  74 .SH CONFORMING TO
  75 This system call is Linux-specific.
  76 .SH NOTES
  77 kexec_load is currently not defined in glibc. To call it use:
  78 .in +4n
  79 .nf
  80 #define _GNU_SOURCE
  81 #include <syscall.h>
  82 #include <asm/unistd.h>
  83 #include <linux/kexec.h>
  84
  85 ret = syscall(__NR_kexec_load, entry, nr_segments, segments, flags);
  86 .fi
  87 .in
  88 .PP
  89 .I linux/kexec.h as a exported header is only available in 2.6.38
  90 and later kernels, in earlier kernels the constants need to be copied
  91 out of the kernel source.
  92 .SH SEE ALSO
  93 .BR syscall (2),
  94 .BR reboot (2)