diff --git a/lib/libsys/kexec_load.2 b/lib/libsys/kexec_load.2
new file mode 100644
--- /dev/null
+++ b/lib/libsys/kexec_load.2
@@ -0,0 +1,125 @@
+.\" Copyright (c) 2025
+.\"	Juniper Networks, Inc.  All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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+.\"
+.Dd August 26, 2025
+.Dt KEXEC_LOAD 2
+.Os
+.Sh NAME
+.Nm kexec_load
+.Nd prepare new kernel to reboot into
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.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
+.Fn reboot 2 .
+.Pp
+The
+.Fa flags
+argument is a bitmask of flags that control the operation of the call.
+This argument is currently unused.
+.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.
+.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.
+.Pp
+The
+.Fn kexec_load 2
+system call stages the kernel image in safe memory along with all
+machine-dependent image data until
+.Fn 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.
+.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.
diff --git a/lib/libsys/reboot.2 b/lib/libsys/reboot.2
--- a/lib/libsys/reboot.2
+++ b/lib/libsys/reboot.2
@@ -126,6 +126,10 @@
 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.,
@@ -149,6 +153,7 @@
 The caller is not the super-user.
 .El
 .Sh SEE ALSO
+.Xr kexec_load 2 ,
 .Xr crash 8 ,
 .Xr halt 8 ,
 .Xr init 8 ,