passing userspace buffer to kernel

I want to compare the performance when we copy skb from kernel to us开发者_运维技巧erspace using DMA and normal skb_copy_datagram_iovec(). I create a module to test. May anyone show me how we can create a big buffer from userspace and pass it to my module (as tcp_recvmsg() is passed an iovec from userspace). Any suggestions are appreciated. Thanks in advance!

Write a Linux character device driver and implement the writev method. For details check out Linux Device Drivers latest edition.