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CentOS 7.0 - man page for kexec_load (centos section 2)

KEXEC_LOAD(2)						     Linux Programmer's Manual						     KEXEC_LOAD(2)

kexec_load - load a new kernel for later execution
#include <linux/kexec.h> long kexec_load(unsigned long entry, unsigned long nr_segments, struct kexec_segment *segments, unsigned long flags); Note: There is no glibc wrapper for this system call; see NOTES.
The kexec_load() system call loads a new kernel that can be executed later by reboot(2). The flags argument is a mask whose high-order bits control the operation of the call. The following values can be specified in flags: KEXEC_ON_CRASH (since Linux 2.6.13) Execute the new kernel automatically on a system crash. KEXEC_PRESERVE_CONTEXT (since Linux 2.6.27) Preserve the system hardware and software states before executing the new kernel. This could be used for system suspend. This flag is available only if the kernel was configured with CONFIG_KEXEC_JUMP, and is effective only if nr_segments is greater than 0. The low-order bits of flags contain the architecture of the to-be-executed kernel. Specify (OR) the constant KEXEC_ARCH_DEFAULT to use the current architecture, or one of the following architecture constants KEXEC_ARCH_386, KEXEC_ARCH_X86_64, KEXEC_ARCH_PPC, KEXEC_ARCH_PPC64, KEXEC_ARCH_IA_64, KEXEC_ARCH_ARM, KEXEC_ARCH_S390, KEXEC_ARCH_SH, KEXEC_ARCH_MIPS, and KEXEC_ARCH_MIPS_LE. The architecture must be exe- cutable on the CPU of the system. The entry argument is the physical entry address in the kernel image. The nr_segments argument is the number of segments pointed to by the segments pointer. The segments argument is an array of kexec_segment structures which define the kernel layout: struct kexec_segment { void *buf; /* Buffer in user space */ size_t bufsz; /* Buffer length in user space */ void *mem; /* Physical address of kernel */ size_t memsz; /* Physical address length */ }; The kernel image defined by segments is copied from the calling process into previously reserved memory.
On success, kexec_load() returns 0. On error, -1 is returned and errno is set to indicate the error.
EBUSY Another crash kernel is already being loaded or a crash kernel is already in use. EINVAL flags is invalid; or nr_segments is too large EPERM The caller does not have the CAP_SYS_BOOT capability.
The kexec_load() system call first appeared in Linux 2.6.13.
This system call is Linux-specific.
Currently, there is no glibc support for kexec_load(). Call it using syscall(2). The required constants are in the Linux kernel source file linux/kexec.h, which is not currently exported to glibc. Therefore, these con- stants must be defined manually. This system call is available only if the kernel was configured with CONFIG_KEXEC.
reboot(2), syscall(2)
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at Linux 2012-07-13 KEXEC_LOAD(2)