kexec_load(2) 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 bit mask that controls 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 high-order bits (corresponding to the mask 0xffff0000) 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_68K, 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 executable 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 kernel imposes an (arbitrary) limit of 16 on the number of segments. 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.


Another crash kernel is already being loaded or a crash kernel is already in use.
flags is invalid; or nr_segments is too large
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 constants must be defined manually.

This system call is available only if the kernel was configured with CONFIG_KEXEC.


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