C# use System.Type as Generic parameter

You can't, directly. The point of generics is to provide compile-time type safety, where you know the type you're interested in at compile-time, and can work with instances of that type. In your case, you only know the Type so you can't get any compile-time checks that any objects you have are instances of that type.

You'll need to call the method via reflection - something like this:

// Get the generic type definition
MethodInfo method = typeof(Session).GetMethod("Linq", 
                                BindingFlags.Public | BindingFlags.Static);

// Build a method with the specific type argument you're interested in
method = method.MakeGenericMethod(typeOne);
// The "null" is because it's a static method
method.Invoke(null, arguments);

If you need to use this type a lot, you might find it more convenient to write your own generic method which calls whatever other generic methods it needs, and then call your method with reflection.

To do this you need to use reflection:

typeof(Session).GetMethod("Linq").MakeGenericMethod(typeOne).Invoke(null, null);

(assuming that Linq<T>() is a static method on the type Session)

If Session is actually an object, you'll need to know where the Linq method is actually declared, and pass in Session as an argument:

typeof(DeclaringType).GetMethod("Linq").MakeGenericMethod(typeOne)
     .Invoke(null, new object[] {Session});