Find specific Neoverse features

Versions of Arm-based instances on Neoverse

To confirm the CPU architecture on your system, use the following command to extract a human-readable string:

    

        
        
lscpu | grep -i model

    

The output will include a line such as Model name: Neoverse-V3-AE or similar, depending on your hardware. This string is important if you need to specify the CPU type for cross-compiling and passing the -mcpu flag to compilers. If the model name is not output, which can occur do to the lscpu utility not being aware of recent CPUs, you can extract the CPU part number with the tip below.

    

        
        
grep "CPU part" /proc/cpuinfo | sort -u

    

    

        
        CPU part        : 0xd83

        
    

Identify supported CPU features

To identify Arm architecture features at runtime in a C program, you can use the Linux hardware capabilities (HWCAP) vector. The source code below reads a specific vector that contains this information.

Use a text editor to copy and paste the C program below into a file named hw_cap.c:

    

        
        
#include <stdio.h>
#include <sys/auxv.h>
#include <asm/hwcap.h>

int main()
{
    long hwcaps = getauxval(AT_HWCAP);

    if (hwcaps & HWCAP_AES) {
        printf("AES instructions are available\n");
    } else {
        printf("AES instructions are not available\n");
    }
    if (hwcaps & HWCAP_CRC32) {
        printf("CRC32 instructions are available\n");
    } else {
        printf("CRC32 instructions are not available\n");
    }
    if (hwcaps & HWCAP_PMULL) {
        printf("PMULL/PMULL2 instructions that operate on 64-bit data are available\n");
    } else {
        printf("PMULL/PMULL2 instructions are not available\n");
    }
    if (hwcaps & HWCAP_SHA1) {
        printf("SHA1 instructions are available\n");
    } else {
        printf("SHA1 instructions are not available\n");
    }
    if (hwcaps & HWCAP_SHA2) {
        printf("SHA2 instructions are available\n");
    } else {
        printf("SHA2 instructions are not available\n");
    }
    if (hwcaps & HWCAP_SVE) {
        printf("Scalable Vector Extension (SVE) instructions are available\n");
    } else {
        printf("Scalable Vector Extension (SVE) instructions are not available\n");
    }

    return 0;
}

    

Compile and run the program with the compiler installed in the previous section:

    

        
        
gcc-16 hw_cap.c -o hw_cap
./hw_cap

    

The output below confirms that Scalable Vector Extensions (SVE) are available:

    

        
        AES instructions are available
CRC32 instructions are available
PMULL/PMULL2 instructions that operate on 64-bit data are available
SHA1 instructions are available
SHA2 instructions are available
Scalable Vector Extension (SVE) instructions are available

        
    

For the latest list of all hardware capabilities available for a specific Linux kernel version, see the arch/arm/include/uapi/asm/hwcap.h header file in the Linux Kernel source code.

Additionally, knowing the SVE vector width is useful for optimizing software performance.

Use a text editor to copy and paste the following C code into a file named sve_width.c:

    

        
        
#include <arm_sve.h>
#include <stdio.h>

int main() {
    int sve_width = svcntb();
    printf("SVE vector length: %d bytes\n", sve_width);
    return 0;
}

    

Compile and run the program with the following commands:

    

        
        
g++-16 -mcpu=neoverse-v3ae sve_width.c -o sve_width 
./sve_width

    

The output shows that the Arm AGI CPU has a SVE width of 16 bytes (128 bits).

    

        
        SVE vector length: 16 bytes

        
    

Supported Compiler Features

Fortunately, the g++ compiler automatically identifies the host system’s capability. You can use the -### argument to show the full options used when compiling.

You can observe which processors are potential targets for compiling your code using the following g++ command:

    

        
        
g++ -E -mcpu=help -xc /dev/null

    

The output is:

    

        
        cc1: note: valid arguments are: cortex-a34 cortex-a35 cortex-a53 cortex-a57 cortex-a72 cortex-a73 thunderx thunderxt88 thunderxt88p1 octeontx octeontx81 octeontx83 thunderxt81 thunderxt83 ampere1 ampere1a ampere1b ampere1c emag xgene1 falkor qdf24xx exynos-m1 phecda thunderx2t99p1 vulcan thunderx2t99 cortex-a55 cortex-a75 cortex-a76 cortex-a76ae cortex-a77 cortex-a78 cortex-a78ae cortex-a78c cortex-a65 cortex-a65ae cortex-x1 cortex-x1c neoverse-n1 ares neoverse-e1 octeontx2 octeontx2t98 octeontx2t96 octeontx2t93 octeontx2f95 octeontx2f95n octeontx2f95mm a64fx fujitsu-monaka hip12 tsv110 thunderx3t110 neoverse-v1 zeus neoverse-512tvb saphira oryon-1 cortex-a57.cortex-a53 cortex-a72.cortex-a53 cortex-a73.cortex-a35 cortex-a73.cortex-a53 cortex-a75.cortex-a55 cortex-a76.cortex-a55 cortex-r82 cortex-r82ae apple-a12 apple-m1 apple-m1 apple-m1 apple-m1 apple-m2 apple-m2 apple-m2 apple-m2 apple-m3 apple-m3 apple-m3 apple-m4 apple-m4 apple-m4 cortex-a510 cortex-a520 cortex-a520ae cortex-a710 cortex-a715 cortex-a720 cortex-a720ae cortex-a725 cortex-a320 cortex-x2 cortex-x3 cortex-x4 cortex-x925 neoverse-n2 cobalt-100 neoverse-n3 neoverse-v2 grace neoverse-v3 neoverse-v3ae c1-nano c1-pro c1-premium c1-ultra demeter olympus gb10 generic generic-armv8-a generic-armv9-a

        
    

Comparing the same command using default g++ version 13.3.0 shows that there are fewer CPU targets available, with notably omission of Neoverse V3-AE architecture, used in the 1st generation Arm AGI CPU.

    

        
        
g++ -E -mcpu=help -xc /dev/null

    

The output from version 13 is:

    

        
        cc1: note: valid arguments are: cortex-a35 cortex-a53 cortex-a57 cortex-a72 cortex-a73 thunderx thunderxt88p1 thunderxt88 octeontx octeontx81 octeontx83 thunderxt81 thunderxt83 emag xgene1 falkor qdf24xx exynos-m1 phecda thunderx2t99p1 vulcan thunderx2t99 cortex-a55 cortex-a75 cortex-a76 ares neoverse-n1 neoverse-e1 a64fx tsv110 zeus neoverse-v1 neoverse-512tvb saphira neoverse-n2 cortex-a57.cortex-a53 cortex-a72.cortex-a53 cortex-a73.cortex-a35 cortex-a73.cortex-a53 cortex-a75.cortex-a55 cortex-a76.cortex-a55 generic