ISA & Extensions

Base ISA Variants

Base ISA		misa	GCC Macro
rv32e	Reduced version of the 32 bit integer ISA designed for embedded systems	0x00000010 (bit 4)	`__riscv __riscv_32e __riscv_xlen=32`
rv32i	A 32 bit integer ISA sufficient to form a compiler target and to support modern operating system environment	0x00000100 (bit 8)	`__riscv __riscv_xlen=32`
rv64i	A 64 bit integer ISA sufficient to form a compiler target and to support modern operating system environment	0x00000100 (bit 8)	`__riscv __riscv_xlen=64`
rv128	A variant of the RISC-V ISA supporting a flat 128-bit address space	0x00000100 (bit 8)

Extension		misa	GCC Macro	Version
M	Integer Multiply/Divide extension	0x00001000 (bit 12)	`__riscv_mul __riscv_div __riscv_muldiv`	2.0 ratification
A	Atomic extension	0x00000001 (bit 0)	`__riscv_atomic`	2.0 frozen
F	Single-precision floating-point extension	0x00000020 (bit 5)	`__riscv_fdiv __riscv_float_abi_single __riscv_flen=32`	2.2 ratification
D	Double-precision floating-point extension	0x00000008 (bit 3)	`__riscv_fdiv __riscv_float_abi_double __riscv_flen=64`	2.2 ratification
Q	Quad-precision floating-point extension	0x00010000 (bit 16)		2.2 ratification
C	Compressed extension	0x00000004 (bit 2)	`__riscv_compressed`	2.0 ratification
L	Decimal Floating-Point extension	0x00000800 (bit 11)
B	Bit-Manipulation extension	0x00000002 (bit 1)		0.0 draft
J	Dynamically Translated Languages extension	0x00000200 (bit 9)
T	Transactional Memory extension	0x00200000 (bit 21)
P	Packed-SIMD extension	0x00008000 (bit 15)		0.2 draft
V	Vector extension	0x00200000 (bit 21)		0.7 draft
N	User-level interrupts supported	0x00002000 (bit 13)		1.1 draft
Counters	Performance Counter CSRs			2.0 draft
G	Additional standard extensions present	0x00000040 (bit 6)
H	Hypervisor extension	0x00000080 (bit 7)
X	Non-standard extensions present	0x00800000 (bit 23)
Zam	Standard Extension for Misaligned Atomics			0.1 draft
Zicsr	Control and Status Register (CSR) Instructions			2.0 ratification
Zifencei	Instruction-Fetch Fence			2.0 ratification
Ztso	Standard Extension for Total Store Ordering			0.1 frozen