diff --git a/lib/libsys/Makefile.sys b/lib/libsys/Makefile.sys
index bd65b58083c2..1d1a4f1136ce 100644
--- a/lib/libsys/Makefile.sys
+++ b/lib/libsys/Makefile.sys
@@ -1,565 +1,566 @@
 # Implement symbols common to libc and libsys.
 #
 # When dynamically linked, the libc symbols are filtered by the actual
 # implementations in libsys.  When statically linked, both libc and
 # libsys contain full implementations to preserve the API of libc.a.
 #
 # The following variable are programmer-defined:
 #
 # MDASM		Override the default syscall implementation in MIASM
 #		(from syscall.mk below).  Each entry is a source file
 #		name (e.g., vfork.S).
 #		Generally defined in <arch>/Makefile.sys.
 # NOASM		Don't generate system call stubs.  Each entry is an
 #		object file name (e.g., yeild.o).  Don't add more of these.
 # PSEUDO	Generate _<sys> and __sys_<sys> symbols, but not <sys>.
 #		Each entry is a bare syscall name (e.g., "clock_gettime").
 # INTERPOSED	Like PSEUDO, but <sys>.c is added to SRCS.
 #		Used for syscalls intercepted by the threading library.
 #
 .PATH: ${LIBSYS_SRCTOP}/${LIBC_ARCH} ${LIBSYS_SRCTOP}
 
 # Include the generated makefile containing the *complete* list
 # of syscall names in MIASM.
 .include "${SRCTOP}/sys/sys/syscall.mk"
 
 # Include machine dependent definitions.
 .include "${LIBSYS_SRCTOP}/${LIBC_ARCH}/Makefile.sys"
 .if ${LIBC_ARCH} == "i386" || ${LIBC_ARCH} == "amd64"
 .include "${LIBSYS_SRCTOP}/x86/Makefile.sys"
 .endif
 
 SRCS+= clock_gettime.c gettimeofday.c __vdso_gettimeofday.c
 
 # Sources common to both syscall interfaces:
 SRCS+=	\
 	__error.c \
 	__getosreldate.c \
 	getpagesize.c \
 	getpagesizes.c \
 	libsys_sigwait.c
 
 .if ${LIB} == "c"
 # Trapping stubs in dynamic libc to be filtered by libsys.
 SOBJS+=	libc_stubs.pico
 
 # Link the full implementation of ELF auxargs for static libc.
 STATICOBJS+=	auxv.o
 
 STATICOBJS+=	interposing_table.o
 .endif
 
 PSEUDO= \
 	__realpathat \
 	clock_gettime \
 	getlogin \
 	gettimeofday \
 	sched_getcpu
 
 INTERPOSED = \
 	accept \
 	accept4 \
 	aio_suspend \
 	clock_nanosleep \
 	close \
 	connect \
 	fcntl \
 	fdatasync \
 	fsync \
 	fork \
 	kevent \
 	msync \
 	nanosleep \
 	open \
 	openat \
 	pdfork \
 	poll \
 	ppoll \
 	pselect \
 	ptrace \
 	read \
 	readv \
 	recvfrom \
 	recvmsg \
 	select \
 	sendmsg \
 	sendto \
 	setcontext \
 	sigaction \
 	sigprocmask \
 	sigsuspend \
 	sigtimedwait \
 	sigwait \
 	sigwaitinfo \
 	swapcontext \
 	wait4 \
 	wait6 \
 	write \
 	writev
 
 PSEUDO+=	${INTERPOSED}
 
 # Add machine dependent asm sources:
 SRCS+=${MDASM}
 
 # Look though the complete list of syscalls (MIASM) for names that are
 # not defined with machine dependent implementations (MDASM), not declared
 # without a trival <sys> symbol (PSEUDO).  Add each syscall that satisfies
 # these conditions to the ASM list.
 .for _asm in ${MIASM}
 .if !${MDASM:R:M${_asm:R}} && !${NOASM:R:M${_asm:R}} && !${PSEUDO:M${_asm:R}}
 ASM+=$(_asm)
 .endif
 .endfor
 
 SASM=	${ASM:S/.o/.S/}
 
 SPSEUDO= ${PSEUDO:C/^.*$/_&.S/}
 
 SRCS+=	${SASM} ${SPSEUDO}
 
 SYM_MAPS+=	${LIBSYS_SRCTOP}/syscalls.map
 SYM_MAPS+=	${LIBSYS_SRCTOP}/Symbol.sys.map
 .if exists(${LIBSYS_SRCTOP}/${LIBC_ARCH}/Symbol.sys.map)
 SYM_MAPS+=	${LIBSYS_SRCTOP}/${LIBC_ARCH}/Symbol.sys.map
 .endif
 
 # Generated files
 CLEANFILES+=	${SASM} ${SPSEUDO}
 
 NOTE_GNU_STACK='\t.section .note.GNU-stack,"",%%progbits\n'
 .if ${MACHINE_CPUARCH} == "aarch64"
 FEATURE_NOTE='\#include <sys/elf_common.h>\nGNU_PROPERTY_AARCH64_FEATURE_1_NOTE(GNU_PROPERTY_AARCH64_FEATURE_1_VAL)\n'
 .else
 FEATURE_NOTE=''
 .endif
 
 # Add this file as a dependency of the generated assembly along with
 # the two included files compat.h and SYS.h.  Depending on this Makefile
 # will cause some needless regenerations, but handles both changes in
 # generated assembly and movement between MIASM and PSEUDO/INTERPOSED.
 # The dependency on compat.h and SYS.h should properly be on the
 # <foo>.S-><foo>.o rules, but there are too many .o variants for it to
 # be easy and touching the geneated source files has the same effect in
 # practice.
 __makefile_sys:=	${.PARSEDIR}/${.PARSEFILE}
 __asm_deps=	${__makefile_sys} \
 		${LIBC_SRCTOP}/include/compat.h \
 		${LIBSYS_SRCTOP}/${LIBC_ARCH}/SYS.h
 
 ${SASM}: ${__asm_deps}
 	printf '/* %sgenerated by libsys/Makefile.sys */\n' @ > ${.TARGET}
 	printf '#include "compat.h"\n' >> ${.TARGET}
 	printf '#include "SYS.h"\nRSYSCALL(${.PREFIX})\n' >> ${.TARGET}
 	printf  ${NOTE_GNU_STACK} >>${.TARGET}
 	printf  ${FEATURE_NOTE} >> ${.TARGET}
 
 ${SPSEUDO}: ${__asm_deps}
 	printf '/* %sgenerated by libsys/Makefile.sys */\n' @ > ${.TARGET}
 	printf '#include "compat.h"\n' >> ${.TARGET}
 	printf '#include "SYS.h"\nPSEUDO(${.PREFIX:S/_//})\n' \
 	    >> ${.TARGET}
 	printf ${NOTE_GNU_STACK} >>${.TARGET}
 	printf ${FEATURE_NOTE} >> ${.TARGET}
 
 .if ${LIB} == "sys"
 MAN+=	abort2.2 \
 	accept.2 \
 	access.2 \
 	acct.2 \
 	adjtime.2 \
 	aio_cancel.2 \
 	aio_error.2 \
 	aio_fsync.2 \
 	aio_mlock.2 \
 	aio_read.2 \
 	aio_return.2 \
 	aio_suspend.2 \
 	aio_waitcomplete.2 \
 	aio_write.2 \
 	auxv.3 \
 	bind.2 \
 	bindat.2 \
 	brk.2 \
 	cap_enter.2 \
 	cap_fcntls_limit.2 \
 	cap_ioctls_limit.2 \
 	cap_rights_limit.2 \
 	chdir.2 \
 	chflags.2 \
 	chmod.2 \
 	chown.2 \
 	chroot.2 \
 	clock_gettime.2 \
 	close.2 \
 	closefrom.2 \
 	connect.2 \
 	connectat.2 \
 	copy_file_range.2 \
 	cpuset.2 \
 	cpuset_getaffinity.2 \
 	cpuset_getdomain.2 \
 	creat.2 \
 	dup.2 \
 	eventfd.2 \
 	execve.2 \
 	_exit.2 \
 	extattr_get_file.2 \
 	fcntl.2 \
 	ffclock.2 \
 	fhlink.2 \
 	fhopen.2 \
 	fhreadlink.2 \
 	flock.2 \
 	fork.2 \
 	fspacectl.2 \
 	fsync.2 \
 	getdirentries.2 \
 	getdtablesize.2 \
 	getfh.2 \
 	getfsstat.2 \
 	getgid.2 \
 	getgroups.2 \
 	getitimer.2 \
 	getlogin.2 \
 	getloginclass.2 \
 	getpeername.2 \
 	getpgrp.2 \
 	getpid.2 \
 	getpriority.2 \
 	getrandom.2 \
 	getrlimit.2 \
 	getrlimitusage.2 \
 	getrusage.2 \
 	getsid.2 \
 	getsockname.2 \
 	getsockopt.2 \
 	gettimeofday.2 \
 	getuid.2 \
 	inotify.2 \
 	intro.2 \
 	ioctl.2 \
 	issetugid.2 \
 	jail.2 \
 	kcmp.2 \
 	kenv.2 \
+	kexec_load.2 \
 	kill.2 \
 	kldfind.2 \
 	kldfirstmod.2 \
 	kldload.2 \
 	kldnext.2 \
 	kldstat.2 \
 	kldsym.2 \
 	kldunload.2 \
 	kqueue.2 \
 	ktrace.2 \
 	link.2 \
 	lio_listio.2 \
 	listen.2 \
 	lseek.2 \
 	madvise.2 \
 	membarrier.2 \
 	mincore.2 \
 	minherit.2 \
 	mkdir.2 \
 	mkfifo.2 \
 	mknod.2 \
 	mlock.2 \
 	mlockall.2 \
 	mmap.2 \
 	modfind.2 \
 	modnext.2 \
 	modstat.2 \
 	mount.2 \
 	mprotect.2 \
 	mq_close.2 \
 	mq_getattr.2 \
 	mq_notify.2 \
 	mq_open.2 \
 	mq_receive.2 \
 	mq_send.2 \
 	mq_setattr.2 \
 	mq_unlink.2 \
 	msgctl.2 \
 	msgget.2 \
 	msgrcv.2 \
 	msgsnd.2 \
 	msync.2 \
 	munmap.2 \
 	nanosleep.2 \
 	nfssvc.2 \
 	ntp_adjtime.2 \
 	open.2 \
 	pathconf.2 \
 	pdfork.2 \
 	pipe.2 \
 	poll.2 \
 	posix_fadvise.2 \
 	posix_fallocate.2 \
 	posix_openpt.2 \
 	procctl.2 \
 	profil.2 \
 	pselect.2 \
 	ptrace.2 \
 	quotactl.2 \
 	rctl_add_rule.2 \
 	read.2 \
 	readlink.2 \
 	reboot.2 \
 	recv.2 \
 	rename.2 \
 	revoke.2 \
 	rfork.2 \
 	rmdir.2 \
 	rtprio.2 \
 	sched_get_priority_max.2 \
 	sched_getcpu.3 \
 	sched_setparam.2 \
 	sched_setscheduler.2 \
 	sched_yield.2 \
 	sctp_generic_recvmsg.2 \
 	sctp_generic_sendmsg.2 \
 	sctp_peeloff.2 \
 	select.2 \
 	semctl.2 \
 	semget.2 \
 	semop.2 \
 	send.2 \
 	setcred.2 \
 	setfib.2 \
 	sendfile.2 \
 	setgroups.2 \
 	setpgid.2 \
 	setregid.2 \
 	setresuid.2 \
 	setreuid.2 \
 	setsid.2 \
 	setuid.2 \
 	shmat.2 \
 	shmctl.2 \
 	shmget.2 \
 	shm_open.2 \
 	shutdown.2 \
 	sigaction.2 \
 	sigaltstack.2 \
 	sigfastblock.2 \
 	sigpending.2 \
 	sigprocmask.2 \
 	sigqueue.2 \
 	sigreturn.2 \
 	sigstack.2 \
 	sigsuspend.2 \
 	sigwait.2 \
 	sigwaitinfo.2 \
 	socket.2 \
 	socketpair.2 \
 	stat.2 \
 	statfs.2 \
 	swapon.2 \
 	symlink.2 \
 	sync.2 \
 	sysarch.2 \
 	syscall.2 \
 	thr_exit.2 \
 	thr_kill.2 \
 	thr_new.2 \
 	thr_self.2 \
 	thr_set_name.2 \
 	thr_suspend.2 \
 	thr_wake.2 \
 	timer_create.2 \
 	timer_delete.2 \
 	timer_settime.2 \
 	timerfd.2 \
 	truncate.2 \
 	umask.2 \
 	undelete.2 \
 	unlink.2 \
 	utimensat.2 \
 	utimes.2 \
 	utrace.2 \
 	uuidgen.2 \
 	vfork.2 \
 	wait.2 \
 	write.2 \
 	_umtx_op.2
 
 MAN+= \
 	getpagesize.3 \
 	getpagesizes.3 \
 	lockf.3 \
 	rfork_thread.3 \
 	sleep.3 \
 	usleep.3
 
 MLINKS+=aio_read.2 aio_readv.2 \
 	aio_read.2 aio_read2.2
 MLINKS+=aio_write.2 aio_writev.2 \
 	aio_write.2 aio_write2.2
 MLINKS+=accept.2 accept4.2
 MLINKS+=access.2 eaccess.2 \
 	access.2 faccessat.2
 MLINKS+=auxv.3 elf_aux_info.3
 MLINKS+=brk.2 sbrk.2
 MLINKS+=cap_enter.2 cap_getmode.2
 MLINKS+=cap_fcntls_limit.2 cap_fcntls_get.2
 MLINKS+=cap_ioctls_limit.2 cap_ioctls_get.2
 MLINKS+=chdir.2 fchdir.2
 MLINKS+=chflags.2 chflagsat.2 \
 	chflags.2 fchflags.2 \
 	chflags.2 lchflags.2
 MLINKS+=chmod.2 fchmod.2 \
 	chmod.2 fchmodat.2 \
 	chmod.2 lchmod.2
 MLINKS+=chown.2 fchown.2 \
 	chown.2 fchownat.2 \
 	chown.2 lchown.2
 MLINKS+=chroot.2 fchroot.2
 MLINKS+=clock_gettime.2 clock_getres.2 \
 	clock_gettime.2 clock_settime.2
 MLINKS+=closefrom.2 close_range.2
 MLINKS+=nanosleep.2 clock_nanosleep.2
 MLINKS+=cpuset.2 cpuset_getid.2 \
 	cpuset.2 cpuset_setid.2
 MLINKS+=cpuset_getaffinity.2 cpuset_setaffinity.2
 MLINKS+=cpuset_getdomain.2 cpuset_setdomain.2
 MLINKS+=dup.2 dup2.2
 MLINKS+=eventfd.2 eventfd_read.3 \
 	eventfd.2 eventfd_write.3
 MLINKS+=execve.2 fexecve.2
 MLINKS+=extattr_get_file.2 extattr.2 \
 	extattr_get_file.2 extattr_delete_fd.2 \
 	extattr_get_file.2 extattr_delete_file.2 \
 	extattr_get_file.2 extattr_delete_link.2 \
 	extattr_get_file.2 extattr_get_fd.2 \
 	extattr_get_file.2 extattr_get_link.2 \
 	extattr_get_file.2 extattr_list_fd.2 \
 	extattr_get_file.2 extattr_list_file.2 \
 	extattr_get_file.2 extattr_list_link.2 \
 	extattr_get_file.2 extattr_set_fd.2 \
 	extattr_get_file.2 extattr_set_file.2 \
 	extattr_get_file.2 extattr_set_link.2
 MLINKS+=ffclock.2 ffclock_getcounter.2 \
 	ffclock.2 ffclock_getestimate.2 \
 	ffclock.2 ffclock_setestimate.2
 MLINKS+=fhlink.2 fhlinkat.2
 MLINKS+=fhopen.2 fhstat.2 fhopen.2 fhstatfs.2
 MLINKS+=fork.2 _Fork.2
 MLINKS+=fsync.2 fdatasync.2
 MLINKS+=getdirentries.2 getdents.2
 MLINKS+=getfh.2 lgetfh.2 \
 	getfh.2 getfhat.2
 MLINKS+=getgid.2 getegid.2
 MLINKS+=getitimer.2 setitimer.2
 MLINKS+=getlogin.2 getlogin_r.3
 MLINKS+=getlogin.2 setlogin.2
 MLINKS+=getloginclass.2 setloginclass.2
 MLINKS+=getpgrp.2 getpgid.2
 MLINKS+=getpid.2 getppid.2
 MLINKS+=getpriority.2 setpriority.2
 MLINKS+=getrlimit.2 setrlimit.2
 MLINKS+=getsockopt.2 setsockopt.2
 MLINKS+=gettimeofday.2 settimeofday.2
 MLINKS+=getuid.2 geteuid.2
 MLINKS+=inotify.2 inotify_init.2 \
 	inotify.2 inotify_init1.2 \
 	inotify.2 inotify_add_watch.2 \
 	inotify.2 inotify_add_watch_at.2 \
 	inotify.2 inotify_rm_watch.2
 MLINKS+=intro.2 errno.2
 MLINKS+=jail.2 jail_attach.2 \
 	jail.2 jail_get.2 \
 	jail.2 jail_remove.2 \
 	jail.2 jail_set.2
 MLINKS+=kldunload.2 kldunloadf.2
 MLINKS+=kqueue.2 kevent.2 \
 	kqueue.2 kqueue1.2 \
 	kqueue.2 kqueuex.2 \
 	kqueue.2 EV_SET.3
 MLINKS+=link.2 linkat.2
 MLINKS+=madvise.2 posix_madvise.2
 MLINKS+=mkdir.2 mkdirat.2
 MLINKS+=mkfifo.2 mkfifoat.2
 MLINKS+=mknod.2 mknodat.2
 MLINKS+=mlock.2 munlock.2
 MLINKS+=mlockall.2 munlockall.2
 MLINKS+=modnext.2 modfnext.2
 MLINKS+=mount.2 nmount.2 \
 	mount.2 unmount.2
 MLINKS+=mq_receive.2 mq_timedreceive.2
 MLINKS+=mq_send.2 mq_timedsend.2
 MLINKS+=ntp_adjtime.2 ntp_gettime.2
 MLINKS+=open.2 openat.2
 MLINKS+=pathconf.2 fpathconf.2
 MLINKS+=pathconf.2 lpathconf.2
 MLINKS+=pdfork.2 pdgetpid.2\
 	pdfork.2 pdkill.2
 MLINKS+=pipe.2 pipe2.2
 MLINKS+=poll.2 ppoll.2
 MLINKS+=rctl_add_rule.2 rctl_get_limits.2 \
 	rctl_add_rule.2 rctl_get_racct.2 \
 	rctl_add_rule.2 rctl_get_rules.2 \
 	rctl_add_rule.2 rctl_remove_rule.2
 MLINKS+=read.2 pread.2 \
 	read.2 preadv.2 \
 	read.2 readv.2
 MLINKS+=readlink.2 readlinkat.2
 MLINKS+=recv.2 recvfrom.2 \
 	recv.2 recvmmsg.2 \
 	recv.2 recvmsg.2
 MLINKS+=rename.2 renameat.2
 MLINKS+=rtprio.2 rtprio_thread.2
 MLINKS+=sched_get_priority_max.2 sched_get_priority_min.2 \
 	sched_get_priority_max.2 sched_rr_get_interval.2
 MLINKS+=sched_setparam.2 sched_getparam.2
 MLINKS+=sched_setscheduler.2 sched_getscheduler.2
 MLINKS+=sctp_generic_sendmsg.2 sctp_generic_sendmsg_iov.2
 MLINKS+=select.2 FD_CLR.3 \
 	select.2 FD_ISSET.3 \
 	select.2 FD_SET.3 \
 	select.2 FD_ZERO.3
 MLINKS+=send.2 sendmmsg.2 \
 	send.2 sendmsg.2 \
 	send.2 sendto.2
 MLINKS+=setpgid.2 setpgrp.2
 MLINKS+=setresuid.2 getresgid.2 \
 	setresuid.2 getresuid.2 \
 	setresuid.2 setresgid.2
 MLINKS+=setuid.2 setegid.2 \
 	setuid.2 seteuid.2 \
 	setuid.2 setgid.2
 MLINKS+=shmat.2 shmdt.2
 MLINKS+=shm_open.2 memfd_create.3 \
 	shm_open.2 shm_create_largepage.3 \
 	shm_open.2 shm_unlink.2 \
 	shm_open.2 shm_rename.2
 MLINKS+=sigwaitinfo.2 sigtimedwait.2
 MLINKS+=stat.2 fstat.2 \
 	stat.2 fstatat.2 \
 	stat.2 lstat.2
 MLINKS+=statfs.2 fstatfs.2
 MLINKS+=swapon.2 swapoff.2
 MLINKS+=symlink.2 symlinkat.2
 MLINKS+=syscall.2 __syscall.2
 MLINKS+=timer_settime.2 timer_getoverrun.2 \
 	timer_settime.2 timer_gettime.2
 MLINKS+=timerfd.2 timerfd_create.2 \
 	timerfd.2 timerfd_gettime.2 \
 	timerfd.2 timerfd_settime.2
 MLINKS+=thr_kill.2 thr_kill2.2
 MLINKS+=truncate.2 ftruncate.2
 MLINKS+=unlink.2 unlinkat.2
 MLINKS+=unlink.2 funlinkat.2
 MLINKS+=utimensat.2 futimens.2
 MLINKS+=utimes.2 futimes.2 \
 	utimes.2 futimesat.2 \
 	utimes.2 lutimes.2
 MLINKS+=wait.2 wait3.2 \
 	wait.2 wait4.2 \
 	wait.2 waitpid.2 \
 	wait.2 waitid.2 \
 	wait.2 wait6.2
 MLINKS+=write.2 pwrite.2 \
 	write.2 pwritev.2 \
 	write.2 writev.2
 .endif # ${LIB} == "sys"
diff --git a/lib/libsys/kexec_load.2 b/lib/libsys/kexec_load.2
new file mode 100644
index 000000000000..c3d458f34100
--- /dev/null
+++ b/lib/libsys/kexec_load.2
@@ -0,0 +1,119 @@
+.\"
+.\" SPDX-License-Identifier: BSD-3-Clause
+.\"
+.\" Copyright (c) 2025	Juniper Networks, Inc.
+.\"
+.Dd October 29, 2025
+.Dt KEXEC_LOAD 2
+.Os
+.Sh NAME
+.Nm kexec_load
+.Nd prepare new kernel to reboot into
+.Sh SYNOPSIS
+.Lb libc
+.In sys/kexec.h
+.Ft int
+.Fn kexec_load "uint64_t entry" "unsigned long count" \
+ "struct kexec_segment *segments" "unsigned long flags"
+.Sh DESCRIPTION
+The
+.Fn kexec_load
+system call loads a new kernel that can be executed later by
+.Xr reboot 2 .
+Subsequent calls will replace previously loaded images.
+.Pp
+The
+.Fa flags
+argument is a bitmask of flags that control the operation of the call.
+This argument is present for compatibility with Linux, although it is currently
+unused and must be 0.
+.Pp
+The
+.Fa entry
+argument is the physical address of the entry point of the new kernel image.
+.Pp
+The
+.Fa count
+argument is the number of segments in the image, currently limited to 16.
+A value of 0 will unload the currently staged image, if one exists, without
+staging a new image.
+.Pp
+The
+.Fa segments
+argument is an array of
+.Fa count
+members of the following structure:
+.Bd -literal -offset indent
+struct  kexec_segment {
+    void *buf;
+    size_t bufsz;
+    vm_paddr_t mem;
+    vm_size_t memsz;
+};
+.Ed
+.Pp
+The
+.Va buf
+and
+.Va bufsz
+members specify a memory region in the caller's address space containing the
+source of the segment.
+The
+.Va mem
+and
+.Va memsz
+members specify the target physical region of the segment.
+.Va bufsz
+must be less than or equal to
+.Va memsz ,
+and
+.Va mem
+and
+.Va memsz
+must be page aligned.
+The region covered by
+.Va mem
+must be in the list covered by the
+.Va vm.phys_segs
+sysctl.
+.Pp
+The
+.Fn kexec_load
+system call stages the kernel image in safe memory along with all
+machine-dependent image data until
+.Xr reboot 2
+is called with the
+.Va RB_KEXEC
+flag to load the image and execute the new kernel.
+.Sh RETURN VALUES
+The
+.Fn kexec_load
+system call returns 0 on success.
+On failure, -1 is returned, and
+.Va errno
+is set to indicate the error.
+On success any previously loaded image is unloaded and replaced with the new
+image.
+On failure, the previously loaded image is unchanged.
+.Sh ERRORS
+The following errors may be returned:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+Too many segments in image.
+.It Bq Er EINVAL
+The value of
+.Va bufsz
+is larger than
+.Va memsz
+in one or more segments.
+.It Bq Er EINVAL
+Machine-dependent load error.
+.It Bq Er EBUSY
+Another
+.Fn kexec_load
+call is in progress.
+.Sh HISTORY
+The
+.Nm
+system call appeared in
+.Fx 16.0 .
diff --git a/lib/libsys/reboot.2 b/lib/libsys/reboot.2
index f6c7bf6c83cc..54fa8b599cd5 100644
--- a/lib/libsys/reboot.2
+++ b/lib/libsys/reboot.2
@@ -1,162 +1,167 @@
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-.Dd July 10, 2018
+.Dd October 29, 2025
 .Dt REBOOT 2
 .Os
 .Sh NAME
 .Nm reboot
 .Nd reboot system or halt processor
 .Sh LIBRARY
 .Lb libc
 .Sh SYNOPSIS
 .In unistd.h
 .In sys/reboot.h
 .Ft int
 .Fn reboot "int howto"
 .Sh DESCRIPTION
 The
 .Fn reboot
 system call
 reboots the system.
 Only the super-user may reboot a machine on demand.
 However, a reboot is invoked
 automatically in the event of unrecoverable system failures.
 .Pp
 The
 .Fa howto
 argument
 is a mask of options; the system call interface allows the following
 options, defined in the include file
 .In sys/reboot.h ,
 to be passed
 to the new kernel or the new bootstrap and init programs.
 .Bl -tag -width RB_POWERCYCLE
 .It Dv RB_AUTOBOOT
 The default, causing the system to reboot in its usual fashion.
 .It Dv RB_ASKNAME
 Normally the system only prompts the user if the loader specified root
 file system has an error.
 This flag forces it to always prompt the user for the root partition.
 .It Dv RB_DFLTROOT
 Use the compiled in root device.
 Normally, the system uses the device from which it was booted
 as the root device if possible.
 (The default behavior is dependent on the ability of the bootstrap program
 to determine the drive from which it was loaded, which is not possible
 on all systems.)
 .It Dv RB_DUMP
 Dump kernel memory before rebooting; see
 .Xr savecore 8
 for more information.
 .It Dv RB_HALT
 The processor is simply halted; no reboot takes place.
 This option should be used with caution.
 .It Dv RB_POWERCYCLE
 After halting, the shutdown code will do what it can to turn
 off the power and then turn the power back on.
 This requires hardware support, usually an auxiliary microprocessor
 that can sequence the power supply.
 At present only the
 .Xr ipmi 4
 driver implements this feature.
 .It Dv RB_POWEROFF
 After halting, the shutdown code will do what it can to turn
 off the power.
 This requires hardware support.
 .It Dv RB_KDB
 Load the symbol table and enable a built-in debugger in the system.
 This option will have no useful function if the kernel is not configured
 for debugging.
 Several other options have different meaning if combined
 with this option, although their use may not be possible
 via the
 .Fn reboot
 system call.
 See
 .Xr ddb 4
 for more information.
 .It Dv RB_NOSYNC
 Normally, the disks are sync'd (see
 .Xr sync 8 )
 before the processor is halted or rebooted.
 This option may be useful if file system changes have been made manually
 or if the processor is on fire.
 .It Dv RB_REROOT
 Instead of rebooting, unmount all filesystems except the one containing
 currently-running executable, and mount root filesystem using the same
 mechanism which is used during normal boot, based on
 vfs.root.mountfrom
 .Xr kenv 1
 variable.
 .It Dv RB_RDONLY
 Initially mount the root file system read-only.
 This is currently the default, and this option has been deprecated.
 .It Dv RB_SINGLE
 Normally, the reboot procedure involves an automatic disk consistency
 check and then multi-user operations.
 .Dv RB_SINGLE
 prevents this, booting the system with a single-user shell
 on the console.
 .Dv RB_SINGLE
 is actually interpreted by the
 .Xr init 8
 program in the newly booted system.
+.It Dv RB_KEXEC
+Execute a new kernel loaded via
+.Fn kexec_load 2 .
+If no kernel was loaded, reboot as normal.
 .El
 .Pp
 When no options are given (i.e.,
 .Dv RB_AUTOBOOT
 is used), the system is
 rebooted from file
 .Dq kernel
 in the root file system of unit 0
 of a disk chosen in a processor specific way.
 An automatic consistency check of the disks is normally performed
 (see
 .Xr fsck 8 ) .
 .Sh RETURN VALUES
 If successful, this call never returns.
 Otherwise, a -1 is returned and an error is returned in the global
 variable
 .Va errno .
 .Sh ERRORS
 .Bl -tag -width Er
 .It Bq Er EPERM
 The caller is not the super-user.
 .El
 .Sh SEE ALSO
+.Xr kexec_load 2 ,
 .Xr crash 8 ,
 .Xr halt 8 ,
 .Xr init 8 ,
 .Xr reboot 8 ,
 .Xr savecore 8 ,
 .Xr reboot 9
 .Sh HISTORY
 The
 .Fn reboot
 system call appeared in
 .Bx 4.0 .