CPU Identification¶

Header: libxs_cpuid.h

Portable CPU feature detection for x86-64, AArch64, and RISC-V targets. Returns an ISA level that can be compared numerically -- higher values indicate more capable instruction sets. x86 levels use thermometer ordering: higher numeric value implies all features of lower levels. AVX10/256 sits below AVX512 because it lacks 512-bit vectors.

ISA Constants¶

Constant	Value	Architecture
`LIBXS_TARGET_ARCH_UNKNOWN`	0	Unknown / unsupported
`LIBXS_TARGET_ARCH_GENERIC`	1	Portable scalar baseline
`LIBXS_X86_GENERIC`	1002	x86-64 baseline
`LIBXS_X86_SSE3`	1003	SSE3
`LIBXS_X86_SSE42`	1004	SSE4.2
`LIBXS_X86_AVX`	1005	AVX
`LIBXS_X86_AVX2`	1006	AVX2 + FMA
`LIBXS_X86_AVX10_256`	1030	AVX10.1/256: all features, 256-bit max (Sierra Forest)
`LIBXS_X86_AVX512`	1100	AVX-512 (F + CD + DQ + BW + VL + VNNI)
`LIBXS_X86_AVX512_AMX`	1105	AVX-512 + AMX (TILE + INT8 + BF16); Sapphire/Granite Rapids
`LIBXS_X86_AVX512_INT8`	1110	AVX-512 + AVX-VNNI-INT8 (VPDPBUUD/BSSD)
`LIBXS_X86_AVX10_512`	1200	AVX10.1/512 + AMX + INT8: full feature set
`LIBXS_AARCH64`	2001	ARMv8.1 baseline
`LIBXS_AARCH64_SVE128`	2201	SVE 128-bit
`LIBXS_AARCH64_SVE256`	2301	SVE 256-bit
`LIBXS_AARCH64_SVE512`	2401	SVE 512-bit
`LIBXS_RV64_MVL128`	3001	RISC-V RVV 128-bit
`LIBXS_RV64_MVL256`	3002	RISC-V RVV 256-bit
`LIBXS_RV64_MVL128_LMUL`	3003	RISC-V RVV 128-bit (non-unit LMUL)
`LIBXS_RV64_MVL256_LMUL`	3004	RISC-V RVV 256-bit (non-unit LMUL)
`LIBXS_X86_ALLFEAT`	1999	x86 sentinel (all features)
`LIBXS_AARCH64_ALLFEAT`	2999	AArch64 sentinel (all features)
`LIBXS_RV64_ALLFEAT`	3999	RISC-V sentinel (all features)

Types¶

typedef struct libxs_cpuid_t {
  char model[256];   /* CPU model name from OS */
  int constant_tsc;  /* non-zero if TSC is invariant */
} libxs_cpuid_t;

Functions¶

int libxs_cpuid(libxs_cpuid_t* info);

Detect the ISA level of the current platform. Optionally fills info with the CPU model name and TSC capability. Returns a constant from the table above.

const char* libxs_cpuid_name(int id);

Returns a human-readable string for the given ISA constant, e.g., "avx2".

int libxs_cpuid_id(const char* name);

Translates a name (e.g., "avx512") to the corresponding ISA constant.

int libxs_cpuid_vlen(int id);

Returns the SIMD vector length in bytes for the given ISA level (0 for scalar-only targets).

int libxs_cpuid_amx_enable(void);

Request AMX tile state (XTILE_DATA) from the OS. Must be called before any AMX tile instruction. Returns EXIT_SUCCESS if tiles are ready (or were already enabled), EXIT_FAILURE on unsupported platform or OS refusal. Not called automatically by libxs_cpuid to avoid the per-thread XSAVE overhead for non-AMX workloads.