Most system calls, including bzero, are not available on the device hence can’t be called.
Are you trying to call bzero directly? If so, then try changing this to an explicit loop.
Otherwise, is this code Fortran where you have something like “A=0” where A is an array? If so, try compiling with “-Mnoidiom” so the compiler doesn’t implicitly replace this with a call to bzero.
Can you post an example of the loop you’re trying to offload? This would help to understand what the issue is.