+++ /dev/null
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-.\"
-.TH KEXEC_LOAD 2 2017-09-15 "Linux" "Linux Programmer's Manual"
-.SH NAME
-kexec_load, kexec_file_load \- load a new kernel for later execution
-.SH SYNOPSIS
-.nf
-.B #include <linux/kexec.h>
-.PP
-.BI "long kexec_load(unsigned long " entry ", unsigned long " nr_segments ","
-.BI " struct kexec_segment *" segments \
-", unsigned long " flags ");"
-.PP
-.BI "long kexec_file_load(int " kernel_fd ", int " initrd_fd ","
-.BI " unsigned long " cmdline_len \
-", const char *" cmdline ","
-.BI " unsigned long " flags ");"
-.fi
-.PP
-.IR Note :
-There are no glibc wrappers for these system calls; see NOTES.
-.SH DESCRIPTION
-The
-.BR kexec_load ()
-system call loads a new kernel that can be executed later by
-.BR reboot (2).
-.PP
-The
-.I flags
-argument is a bit mask that controls the operation of the call.
-The following values can be specified in
-.IR flags :
-.TP
-.BR KEXEC_ON_CRASH " (since Linux 2.6.13)"
-Execute the new kernel automatically on a system crash.
-This "crash kernel" is loaded into an area of reserved memory that
-is determined at boot time using the
-.I crashkernel
-kernel command-line parameter.
-The location of this reserved memory is exported to user space via the
-.I /proc/iomem
-file, in an entry labeled "Crash kernel".
-A user-space application can parse this file and prepare a list of
-segments (see below) that specify this reserved memory as destination.
-If this flag is specified, the kernel checks that the
-target segments specified in
-.I segments
-fall within the reserved region.
-.TP
-.BR 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
-.BR CONFIG_KEXEC_JUMP ,
-and is effective only if
-.I nr_segments
-is greater than 0.
-.PP
-The high-order bits (corresponding to the mask 0xffff0000) of
-.I flags
-contain the architecture of the to-be-executed kernel.
-Specify (OR) the constant
-.B KEXEC_ARCH_DEFAULT
-to use the current architecture,
-or one of the following architecture constants
-.BR KEXEC_ARCH_386 ,
-.BR KEXEC_ARCH_68K ,
-.BR KEXEC_ARCH_X86_64 ,
-.BR KEXEC_ARCH_PPC ,
-.BR KEXEC_ARCH_PPC64 ,
-.BR KEXEC_ARCH_IA_64 ,
-.BR KEXEC_ARCH_ARM ,
-.BR KEXEC_ARCH_S390 ,
-.BR KEXEC_ARCH_SH ,
-.BR KEXEC_ARCH_MIPS ,
-and
-.BR KEXEC_ARCH_MIPS_LE .
-The architecture must be executable on the CPU of the system.
-.PP
-The
-.I entry
-argument is the physical entry address in the kernel image.
-The
-.I nr_segments
-argument is the number of segments pointed to by the
-.I segments
-pointer;
-the kernel imposes an (arbitrary) limit of 16 on the number of segments.
-The
-.I segments
-argument is an array of
-.I kexec_segment
-structures which define the kernel layout:
-.PP
-.in +4n
-.EX
-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 */
-};
-.EE
-.in
-.PP
-The kernel image defined by
-.I segments
-is copied from the calling process into
-the kernel either in regular
-memory or in reserved memory (if
-.BR KEXEC_ON_CRASH
-is set).
-The kernel first performs various sanity checks on the
-information passed in
-.IR segments .
-If these checks pass, the kernel copies the segment data to kernel memory.
-Each segment specified in
-.I segments
-is copied as follows:
-.IP * 3
-.I buf
-and
-.I bufsz
-identify a memory region in the caller's virtual address space
-that is the source of the copy.
-The value in
-.I bufsz
-may not exceed the value in the
-.I memsz
-field.
-.IP *
-.I mem
-and
-.I memsz
-specify a physical address range that is the target of the copy.
-The values specified in both fields must be multiples of
-the system page size.
-.IP *
-.I bufsz
-bytes are copied from the source buffer to the target kernel buffer.
-If
-.I bufsz
-is less than
-.IR memsz ,
-then the excess bytes in the kernel buffer are zeroed out.
-.PP
-In case of a normal kexec (i.e., the
-.BR KEXEC_ON_CRASH
-flag is not set), the segment data is loaded in any available memory
-and is moved to the final destination at kexec reboot time (e.g., when the
-.BR kexec (8)
-command is executed with the
-.I \-e
-option).
-.PP
-In case of kexec on panic (i.e., the
-.BR KEXEC_ON_CRASH
-flag is set), the segment data is
-loaded to reserved memory at the time of the call, and, after a crash,
-the kexec mechanism simply passes control to that kernel.
-.PP
-The
-.BR kexec_load ()
-system call is available only if the kernel was configured with
-.BR CONFIG_KEXEC .
-.SS kexec_file_load()
-The
-.BR kexec_file_load ()
-system call is similar to
-.BR kexec_load (),
-but it takes a different set of arguments.
-It reads the kernel to be loaded from the file referred to by
-the file descriptor
-.IR kernel_fd ,
-and the initrd (initial RAM disk)
-to be loaded from file referred to by the file descriptor
-.IR initrd_fd .
-The
-.IR cmdline
-argument is a pointer to a buffer containing the command line
-for the new kernel.
-The
-.IR cmdline_len
-argument specifies size of the buffer.
-The last byte in the buffer must be a null byte (\(aq\\0\(aq).
-.PP
-The
-.IR flags
-argument is a bit mask which modifies the behavior of the call.
-The following values can be specified in
-.IR flags :
-.TP
-.BR KEXEC_FILE_UNLOAD
-Unload the currently loaded kernel.
-.TP
-.BR KEXEC_FILE_ON_CRASH
-Load the new kernel in the memory region reserved for the crash kernel
-(as for
-.BR KEXEC_ON_CRASH).
-This kernel is booted if the currently running kernel crashes.
-.TP
-.BR KEXEC_FILE_NO_INITRAMFS
-Loading initrd/initramfs is optional.
-Specify this flag if no initramfs is being loaded.
-If this flag is set, the value passed in
-.IR initrd_fd
-is ignored.
-.PP
-The
-.BR kexec_file_load ()
-.\" See also http://lwn.net/Articles/603116/
-system call was added to provide support for systems
-where "kexec" loading should be restricted to
-only kernels that are signed.
-This system call is available only if the kernel was configured with
-.BR CONFIG_KEXEC_FILE .
-.SH RETURN VALUE
-On success, these system calls returns 0.
-On error, \-1 is returned and
-.I errno
-is set to indicate the error.
-.SH ERRORS
-.TP
-.B EADDRNOTAVAIL
-.\" See kernel/kexec.::sanity_check_segment_list in the 3.19 kernel source
-The
-.B KEXEC_ON_CRASH
-flags was specified, but the region specified by the
-.I mem
-and
-.I memsz
-fields of one of the
-.I segments
-entries lies outside the range of memory reserved for the crash kernel.
-.TP
-.B EADDRNOTAVAIL
-The value in a
-.I mem
-or
-.I memsz
-field in one of the
-.I segments
-entries is not a multiple of the system page size.
-.TP
-.B EBADF
-.I kernel_fd
-or
-.I initrd_fd
-is not a valid file descriptor.
-.TP
-.B EBUSY
-Another crash kernel is already being loaded
-or a crash kernel is already in use.
-.TP
-.B EINVAL
-.I flags
-is invalid.
-.TP
-.B EINVAL
-The value of a
-.I bufsz
-field in one of the
-.I segments
-entries exceeds the value in the corresponding
-.I memsz
-field.
-.TP
-.B EINVAL
-.IR nr_segments
-exceeds
-.BR KEXEC_SEGMENT_MAX
-(16).
-.TP
-.B EINVAL
-Two or more of the kernel target buffers overlap.
-.TP
-.B EINVAL
-The value in
-.I cmdline[cmdline_len-1]
-is not \(aq\\0\(aq.
-.TP
-.B EINVAL
-The file referred to by
-.I kernel_fd
-or
-.I initrd_fd
-is empty (length zero).
-.TP
-.B ENOEXEC
-.I kernel_fd
-does not refer to an open file, or the kernel can't load this file.
-Currently, the file must be a bzImage and contain an x86 kernel that
-is loadable above 4\ GiB in memory (see the kernel source file
-.IR Documentation/x86/boot.txt ).
-.TP
-.B ENOMEM
-Could not allocate memory.
-.TP
-.B EPERM
-The caller does not have the
-.BR CAP_SYS_BOOT
-capability.
-.SH VERSIONS
-The
-.BR kexec_load ()
-system call first appeared in Linux 2.6.13.
-The
-.BR kexec_file_load ()
-system call first appeared in Linux 3.17.
-.SH CONFORMING TO
-These system calls are Linux-specific.
-.SH NOTES
-Currently, there is no glibc support for these system calls.
-Call them using
-.BR syscall (2).
-.SH SEE ALSO
-.BR reboot (2),
-.BR syscall (2),
-.BR kexec (8)
-.PP
-The kernel source files
-.IR Documentation/kdump/kdump.txt
-and
-.IR Documentation/admin-guide/kernel-parameters.txt
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