12 files changed, 190 insertions, 14 deletions
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
@@ -243,6 +243,7 @@ MAN+=	abort2.2 \
 	jail.2 \
 	kcmp.2 \
 	kenv.2 \
+	kexec_load.2 \
 	kill.2 \
 	kldfind.2 \
 	kldfirstmod.2 \
diff --git a/lib/libsys/_libsys.h b/lib/libsys/_libsys.h
index 6bd768708a78..12417b572a60 100644
--- a/lib/libsys/_libsys.h
+++ b/lib/libsys/_libsys.h
@@ -32,6 +32,7 @@ struct itimerspec;
 struct itimerval;
 struct jail;
 struct kevent;
+struct kexec_segment;
 struct kld_file_stat;
 struct mac;
 struct module_stat;
@@ -470,6 +471,7 @@ typedef int (__sys_getgroups_t)(int, gid_t *);
 typedef int (__sys_setgroups_t)(int, const gid_t *);
 typedef int (__sys_jail_attach_jd_t)(int);
 typedef int (__sys_jail_remove_jd_t)(int);
+typedef int (__sys_kexec_load_t)(uint64_t, u_long, struct kexec_segment *, u_long);
 
 _Noreturn void __sys__exit(int rval);
 int __sys_fork(void);
@@ -876,6 +878,7 @@ int __sys_getgroups(int gidsetsize, gid_t * gidset);
 int __sys_setgroups(int gidsetsize, const gid_t * gidset);
 int __sys_jail_attach_jd(int fd);
 int __sys_jail_remove_jd(int fd);
+int __sys_kexec_load(uint64_t entry, u_long nseg, struct kexec_segment * segments, u_long flags);
 __END_DECLS
 
 #endif /* __LIBSYS_H_ */
diff --git a/lib/libsys/clock_gettime.2 b/lib/libsys/clock_gettime.2
index 89551d0f720b..841673648dfc 100644
--- a/lib/libsys/clock_gettime.2
+++ b/lib/libsys/clock_gettime.2
@@ -27,7 +27,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd August 10, 2024
+.Dd October 15, 2025
 .Dt CLOCK_GETTIME 2
 .Os
 .Sh NAME
@@ -80,7 +80,6 @@ Behavior during a leap second is not defined by and POSIX standard.
 Increments in SI seconds, even while the system is suspended.
 Its epoch is unspecified.
 The count is not adjusted by leap seconds.
-.Fx implements
 .It Dv CLOCK_UPTIME
 .It Dv CLOCK_UPTIME_PRECISE
 .It Dv CLOCK_UPTIME_FAST
diff --git a/lib/libsys/closefrom.2 b/lib/libsys/closefrom.2
index 1885a6fdeaa8..e6b4a5a3e9d7 100644
--- a/lib/libsys/closefrom.2
+++ b/lib/libsys/closefrom.2
@@ -23,7 +23,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd May 17, 2025
+.Dd October 27, 2025
 .Dt CLOSEFROM 2
 .Os
 .Sh NAME
@@ -94,6 +94,11 @@ function first appeared in
 .Fx 8.0 .
 .Pp
 The
+.Fn close_range
+function first appeared in
+.Fx 12.2 .
+.Pp
+The
 .Dv CLOSE_RANGE_CLOFORK
 flag appeared in
 .Fx 15.0 .
diff --git a/lib/libsys/getrlimitusage.2 b/lib/libsys/getrlimitusage.2
index e2114def56c2..d0e92d7f88b4 100644
--- a/lib/libsys/getrlimitusage.2
+++ b/lib/libsys/getrlimitusage.2
@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd September 27, 2024
+.Dd October 24, 2025
 .Dt GETRLIMITUSAGE 2
 .Os
 .Sh NAME
@@ -97,4 +97,4 @@ and
 The
 .Fn getrlimitusage
 system call appeared in
-.Bx 15.0 .
+.Fx 14.2 .
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/pathconf.2 b/lib/libsys/pathconf.2
index 5a983a3a13e2..5348128be706 100644
--- a/lib/libsys/pathconf.2
+++ b/lib/libsys/pathconf.2
@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd August 6, 2025
+.Dd October 31, 2025
 .Dt PATHCONF 2
 .Os
 .Sh NAME
@@ -180,7 +180,8 @@ Return 1 if named attributes are enabled for the file system, otherwise 0.
 .It Li _PC_HAS_NAMEDATTR
 Return 1 if one or more named attributes exist for the file, otherwise 0.
 .It Li _PC_HAS_HIDDENSYSTEM
-Return 1 if both
+Return 1 if all of the
+.Dv UF_ARCHIVE ,
 .Dv UF_HIDDEN
 and
 .Dv UF_SYSTEM
@@ -192,6 +193,9 @@ Returns the block size required for block cloning via
 .Xr copy_file_range 2
 for a file system if block cloning is supported,
 otherwise 0.
+.It Li _PC_CASE_INSENSITIVE
+Return 1 if the file system performs case insensitive lookups,
+otherwise 0.
 .El
 .Sh RETURN VALUES
 If the call to
diff --git a/lib/libsys/posix_fallocate.2 b/lib/libsys/posix_fallocate.2
index 8be075b41331..94858c4a0f90 100644
--- a/lib/libsys/posix_fallocate.2
+++ b/lib/libsys/posix_fallocate.2
@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 30, 2020
+.Dd November 2, 2025
 .Dt POSIX_FALLOCATE 2
 .Os
 .Sh NAME
@@ -105,8 +105,7 @@ The
 .Fa len
 argument was less than or equal to zero, the
 .Fa offset
-argument was less than zero,
-or the operation is not supported by the file system.
+argument was less than zero.
 .It Bq Er EIO
 An I/O error occurred while reading from or writing to a file system.
 .It Bq Er EINTEGRITY
@@ -123,6 +122,8 @@ media.
 The file descriptor
 .Fa fd
 has insufficient rights.
+.It Bq Er EOPNOTSUPP
+The operation is not supported by the file system.
 .It Bq Er ESPIPE
 The
 .Fa fd
@@ -137,12 +138,29 @@ argument is associated with a pipe or FIFO.
 The
 .Fn posix_fallocate
 system call conforms to
-.St -p1003.1-2004 .
+.St -p1003.1-2024 .
 .Sh HISTORY
 The
 .Fn posix_fallocate
 function appeared in
 .Fx 9.0 .
+.Pp
+Previous versions of
+.Nm
+used
+.Er EINVAL
+to indicate that the operation is not supported by the file system, as specified
+in
+.St -p1003.1
+Base Specifications, Issue 7.
+.St -p1003.1
+Base Specifications, Issue 8 switched to requiring
+.Er EOPNOTSUPP
+for this error case.
+ZFS adopted the latter convention in
+.Fx 15.0 ,
+and the remaining filesystems in base adopted it in
+.Fx 15.1 .
 .Sh AUTHORS
 .Fn posix_fallocate
 and this manual page were initially written by
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
@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd July 10, 2018
+.Dd October 29, 2025
 .Dt REBOOT 2
 .Os
 .Sh NAME
@@ -126,6 +126,10 @@ on the console.
 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 @@ variable
 The caller is not the super-user.
 .El
 .Sh SEE ALSO
+.Xr kexec_load 2 ,
 .Xr crash 8 ,
 .Xr halt 8 ,
 .Xr init 8 ,
diff --git a/lib/libsys/revoke.2 b/lib/libsys/revoke.2
index f5ae1e92c357..938d2f083e27 100644
--- a/lib/libsys/revoke.2
+++ b/lib/libsys/revoke.2
@@ -28,7 +28,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd January 25, 2016
+.Dd October 24, 2025
 .Dt REVOKE 2
 .Os
 .Sh NAME
@@ -62,7 +62,7 @@ using a special close method which does not block.
 Access to a file may be revoked only by its owner or the super user.
 The
 .Fn revoke
-system call is currently supported only for block and character special
+system call is currently supported only for character special
 device files.
 It is normally used to prepare a terminal device for a new login session,
 preventing any access by a previous user of the terminal.
diff --git a/lib/libsys/syscalls.map b/lib/libsys/syscalls.map
index b5400b9849b3..d00c862eb462 100644
--- a/lib/libsys/syscalls.map
+++ b/lib/libsys/syscalls.map
@@ -817,4 +817,6 @@ FBSDprivate_1.0 {
 	__sys_jail_attach_jd;
 	_jail_remove_jd;
 	__sys_jail_remove_jd;
+	_kexec_load;
+	__sys_kexec_load;
 };
diff --git a/lib/libsys/write.2 b/lib/libsys/write.2
index d2ff41ceead9..77067893ab4c 100644
--- a/lib/libsys/write.2
+++ b/lib/libsys/write.2
@@ -132,6 +132,26 @@ and
 may write fewer bytes than requested;
 the return value must be noted,
 and the remainder of the operation should be retried when possible.
+.Sh ATOMICITY OF WRITES
+When operating on regular files on local file systems, the effects of
+.Fn write
+are atomic.
+As required by the POSIX standard,
+the
+.Fn read ,
+.Fn write ,
+and
+.Fn ftruncate
+functions and their variations are atomic with respect to
+each other on the file data and metadata for regular files.
+See for instance
+.St -p1003.1-2024
+Volume 2, Section 2.9.7 for more information.
+.Pp
+.Fx
+implements the requirement by taking
+a read/write range lock on the file byte range
+affected by the corresponding function.
 .Sh RETURN VALUES
 Upon successful completion the number of bytes which were written
 is returned.