From: Brad Smith <brad@comstyle.com>
Subject: riscv64: Zvkb extension HWCAP
To: tech@openbsd.org
Cc: jsing@openbsd.org
Date: Tue, 19 May 2026 02:38:57 -0400

While porting some software for RISC-V CPU feature detection I noticed
a few pieces of software like Orc and some crypto libraries check for
the RISC-V extension Zvkb.


Index: include/elf.h
===================================================================
RCS file: /cvs/src/sys/arch/riscv64/include/elf.h,v
retrieving revision 1.4
diff -u -p -u -p -r1.4 elf.h
--- include/elf.h	2 May 2026 14:09:17 -0000	1.4
+++ include/elf.h	17 May 2026 23:41:02 -0000
@@ -92,5 +92,6 @@ extern unsigned long hwcap2;
 #define HWCAP2_ISA_ZVKSED	(1UL << 13)	/* Vector ShangMi SM4 */
 #define HWCAP2_ISA_ZVKSH	(1UL << 14)	/* Vector ShangMi SM3 */
 #define HWCAP2_ISA_ZVKT		(1UL << 15)	/* Vector Data-Independent Execution */
+#define HWCAP2_ISA_ZVKB		(1UL << 16)	/* Vector Cryptography Bit Manipulation */
 
 #endif /* !_MACHINE_ELF_H_ */
Index: riscv64/cpu.c
===================================================================
RCS file: /cvs/src/sys/arch/riscv64/riscv64/cpu.c,v
retrieving revision 1.28
diff -u -p -u -p -r1.28 cpu.c
--- riscv64/cpu.c	9 May 2026 17:38:50 -0000	1.28
+++ riscv64/cpu.c	17 May 2026 23:41:02 -0000
@@ -128,6 +128,7 @@ const struct extension {
 	{ "zvksed", 0, HWCAP2_ISA_ZVKSED },
 	{ "zvksh", 0, HWCAP2_ISA_ZVKSH },
 	{ "zvkt", 0, HWCAP2_ISA_ZVKT },
+	{ "zvkb", 0, HWCAP2_ISA_ZVKB },
 	{ NULL, 0, 0 }
 };