Hi Syed, Thanks for the response, in order to check whether the data is in page or not, i tried printing the whole page data, i found that it is present in the page, so i calculate the offset at which the data is present by using *(unsigned long) skb->data - (unsigned long) page_address(page)* seem like it working but my question is will it work in all case. So am using the following code *.* *.* *struct page *page = virt_to_page(skb->data);* *int offset = **(unsigned long) skb->data - (unsigned long) page_address(page);* *skb_add_rx_frag(master_skb, skb_shinfo(master_skb)->nr_frags, page, offset, skb->len)* *.* *.* * * is this the right way to do ? i want to understand how the memory handling are happening in kernel, can some one point me to right material. Thank you, On Wed, Mar 30, 2011 at 1:10 AM, sk.syed2 <sk.syed2@gmail.com> wrote:
. struct page *page = virt_to_page(skb->data); If skb->data page aligned?
. And can some one please tell what is the use of the functions like virt_to_page and kmap_atomic_to_page, Generally to lock the page in memory(esp while doing dma) using get_page().
i tried calling virt_to_page(skb->data), but when i print the data in the page address ( page_address(page) ) and the data in pointed by skb->data, i came to know its mapping to a wrong page. If skb->data is not page aligned then page_address(page) will be equal to skb->data+(somevalue) (on nearest page boundary).
-syed