How does gnark start GPU acceleration?

[weijizhen]

I am at gnark/.../example, a main. go was created, such as the following code:
package main

import (
"github.com/consensys/gnark-crypto/ecc"
"github.com/consensys/gnark/backend"
"github.com/consensys/gnark/backend/groth16"
"github.com/consensys/gnark/frontend"
"github.com/consensys/gnark/frontend/cs/r1cs"
)

// CubicCircuit defines a simple circuit
// x**3 + x + 5 == y
type CubicCircuit struct {
// struct tags on a variable is optional
// default uses variable name and secret visibility.
X frontend.Variable gnark:"x"
Y frontend.Variable gnark:",public"
}

// Define declares the circuit constraints
// x**3 + x + 5 == y
func (circuit *CubicCircuit) Define(api frontend.API) error {
x3 := api.Mul(circuit.X, circuit.X, circuit.X)
api.AssertIsEqual(circuit.Y, api.Add(x3, circuit.X, 5))
return nil
}

func main() {
// compiles our circuit into a R1CS
var circuit CubicCircuit
ccs, _ := frontend.Compile(ecc.BN254.ScalarField(), r1cs.NewBuilder, &circuit)

// groth16 zkSNARK: Setup
pk, vk, _ := groth16.Setup(ccs)

// witness definition
assignment := CubicCircuit{X: 3, Y: 35}
witness, _ := frontend.NewWitness(&assignment, ecc.BN254.ScalarField())
publicWitness, _ := witness.Public()

// groth16: Prove & Verify
proof, _ := groth16.Prove(ccs, pk, witness, backend.WithIcicleAcceleration())
//proof, _ := groth16.Prove(ccs, pk, witness)
groth16.Verify(proof, vk, publicWitness)

}

errors：
/usr/local/go/pkg/tool/linux_amd64/link: running gcc failed: exit status 1
/usr/bin/ld: cannot find -lbn254: No such file or directory
collect2: error: ld returned 1 exit status

Should I download the article first and then compile it?
Finally, to gnark/.../example and to execute "go run -tags=icicle main.go"
What should I do?

[ivokub]

Hi, indeed setting up the GPU support is a bit cumbersome and depends on the ICICLE library being set up correctly. Have a look at https://github.com/ingonyama-zk/icicle/tree/main/wrappers/golang on how to build ICICLE.