@@ -264,3 +264,13 @@ The following keys are defined:
* :c:macro:`RISCV_HWPROBE_KEY_HIGHEST_VIRT_ADDRESS`: An unsigned long which
represent the highest userspace virtual address usable.
+
+* :c:macro:`RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0`: A bitmask containing the
+ thead vendor extensions that are compatible with the
+ :c:macro:`RISCV_HWPROBE_BASE_BEHAVIOR_IMA`: base system behavior.
+
+ * T-HEAD
+
+ * :c:macro:`RISCV_HWPROBE_VENDOR_EXT_XTHEADVECTOR`: The xtheadvector vendor
+ extension is supported in the T-Head ISA extensions spec starting from
+ commit a18c801634 ("Add T-Head VECTOR vendor extension. ").