On Wed, Oct 26, 2016 at 12:52:45PM -0400, David Miller wrote: > From: "Michael S. Tsirkin" <m...@redhat.com> > Date: Wed, 26 Oct 2016 19:36:45 +0300 > > > On Wed, Oct 26, 2016 at 03:52:02PM +0200, Jesper Dangaard Brouer wrote: > >> On Sat, 22 Oct 2016 04:07:23 +0000 > >> Shrijeet Mukherjee <shrij...@gmail.com> wrote: > >> > >> > This patch adds support for xdp ndo and also inserts the xdp program > >> > call into the merged RX buffers and big buffers paths > >> > >> I really appreciate you are doing this for virtio_net. > >> > >> My first question is: Is the (packet) page data writable? > >> (MST might be able to answer?) > >> > >> As this is currently an XDP requirement[1]. > > > > I'm not sure I understand what does writable mean. > > Could you explain a bit more pls? > > We do copy data into skb ATM but I plan to change that. > > The packet data area must be writable,
This is the part I don't fully understand. It's in RAM so of course it's writeable. > and the page it lives in must > not be shared with any other entity in the system. We share pages between arbitrary multiple packets. I think that's OK - or is there an assumption that multiple programs will be attached with different priveledges? > This is because the eBPF program that executes via XDP must be able > to modify and read arbitrary parts of the packet area. -- MST
