diff --git a/riscv-elf.adoc b/riscv-elf.adoc
index 77a43cd3..f03d97e3 100644
--- a/riscv-elf.adoc
+++ b/riscv-elf.adoc
@@ -896,6 +896,7 @@ value if the tag number is even.
 | Tag_RISCV_priv_spec                 |        8 | uleb128        | Indicates the major version of the privileged specification.
 | Tag_RISCV_priv_spec_minor           |       10 | uleb128        | Indicates the minor version of the privileged specification.
 | Tag_RISCV_priv_spec_revision        |       12 | uleb128        | Indicates the revision version of the privileged specification.
+| Tag_RISCV_reserved_registers        |       14 | uleb128        | Indicates the extra reserved register information.
 | Reserved for non-standard attribute | >= 32768 | -              | -
 |===
 
@@ -942,6 +943,24 @@ Tag_RISCV_priv_spec contains the major/minor/revision version information of
 the privileged specification. It will report errors if object files of different
 privileged specification versions are merged.
 
+===== Tag_RISCV_reserved_registers, 14, uleb128=register bit-vector
+
+Tag_RISCV_reserved_registers contains the information about the reserved
+registers which are not reserved by ABI. Registers might be reserved by specific
+compiler option like `-ffixed-x4` or a special purpose ABI variant like
+overlay ABI.
+
+The encoding of Tag_RISCV_reserved_registers is a bit-vector, each bit
+corresponding to a register. The bit number for a register is the same as DWARF
+register numbers.
+
+First bit is must set, used to distinguish between attribute is unset or having
+empty reserved register set.
+
+It will report errors if object files are linked with different
+Tag_RISCV_reserved_registers values, or if the tag is missing from any object
+when the tag is set in at least one linked object.
+
 == Code relaxation
 
 At link time, when all the memory objects have been resolved, the code sequence