[PATCH v3 11/13] riscv: hwprobe: Document thead vendor extensions and xtheadvector extension

[Charlie Jenkins <charlie@rivosinc.com>]

Document support for thead vendor extensions using the key
RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0 and xtheadvector extension using
the key RISCV_HWPROBE_VENDOR_EXT_XTHEADVECTOR.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Evan Green <evan@rivosinc.com>
---
 Documentation/arch/riscv/hwprobe.rst | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst
index 204cd4433af5..9c0ef8c57228 100644
--- a/Documentation/arch/riscv/hwprobe.rst
+++ b/Documentation/arch/riscv/hwprobe.rst
@@ -214,3 +214,13 @@ The following keys are defined:
 
 * :c:macro:`RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE`: An unsigned int which
   represents the size of the Zicboz block in bytes.
+
+* :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. ").

-- 
2.34.1