$ go build -buildmode=plugin w.go
$ go run x.go
FAIL; got *[8675309]int

$ cat x.go
package main

import (
	"plugin"
	"reflect"
)

func main() {
	v := reflect.New(reflect.ArrayOf(8675309, reflect.TypeOf(0))).Interface()

	p, err := plugin.Open("w.so")
	if err != nil {
		panic(err)
	}
	f, err := p.Lookup("F")
	if err != nil {
		panic(err)
	}
	f.(func(interface{}))(v)
}

$ cat w.go
package main

import "fmt"

func F(x interface{}) {
	switch x.(type) {
	case *[8675309]int:
		fmt.Println("ok")
	default:
		fmt.Printf("FAIL; got %T\n", x)
	}
}