CUDBG_SIZE
cudbg = malloc(sizeof(struct t4_cudbg_dump) + CUDBG_SIZE);
err(1, "%s:allocate %d bytes failed", __func__, CUDBG_SIZE);
memset(cudbg, 0, sizeof(struct t4_cudbg_dump) + CUDBG_SIZE);
cudbg->len = CUDBG_SIZE;