Index: share/man/man5/elf.5
===================================================================
--- share/man/man5/elf.5
+++ share/man/man5/elf.5
@@ -1276,6 +1276,46 @@
 This member specifies a constant addend used to compute the value to be
 stored into the relocatable field.
 .El
+.Ss Note Section
+ELF Note sections consist of entries with the following format.
+.Bl -column -offset indent "Sy Field" "Sy Size" "Sy Description"
+.It Sy Field Ta Sy Size Ta Sy Description
+.It namesz   Ta 32 bits Ta Size of "name"
+.It descsz   Ta 32 bits Ta Size of "desc"
+.It type     Ta 32 bits Ta OS-dependent note type
+.It name     Ta namesz  Ta Null-terminated originator name
+.It desc     Ta descsz  Ta OS-dependent note data
+.El
+.Pp
+The name and desc fields are padded to ensure 4-byte alignemnt.
+.Pp
+.Fx defines the following ELF note types
+(with corresponding interpretation of desc):
+.Pp
+.Dv NT_FREEBSD_ABI_TAG
+(OS ABI version)
+Value: 1
+32-bit integer containing expected ABI version (i.e., 
+.Dv __FreeBSD_version )
+.Pp
+.Dv NT_FREEBSD_NOINIT_TAG
+Value: 2
+Indicates that crt does not call init.
+desc is ignored.
+.Pp
+.Dv NT_FREEBSD_ARCH_TAG
+Value: 3
+.Pp
+.Dv NT_FREEBSD_FEATURE_CTL
+(Mitigation / feature enable bits)
+Value: 4
+Contains a bitmask of features to enable:
+.Bl -column -offset indent "Sy Bit" "Sy Description"
+.It 0x01 Ta Disable ASLR
+.It 0x02 Ta Disable implicit PROT_MAX
+.It 0x04 Ta Disable stack gap
+.It 0x08 Ta Binary makes W+X mappings
+.El
 .Sh SEE ALSO
 .Xr as 1 ,
 .Xr gdb 1 ,