On Tue, Dec 17, 2019 at 7:05 AM Vladimír Čunát <vladimir.cunat@xxxxxx> wrote: > > Hello. > > I configured .frame_headroom = 0 (default) but I receive packets with > larger one (256). Am I doing something wrong? Kernel [docs] says: > This is correct. The 256 headroom is for XDP frame's headroom, reserved in driver. So you shouldn't use it. if you configure .frame_headroom = 256, then your frame will start with 256 + 256. > > There is also an option to set the headroom of each single buffer in > the UMEM. If you set this to N bytes, it means that the packet will > start N bytes into the buffer leaving the first N bytes for the > application to use. Yes William > > which doesn't sound to leave an option for kernel-space to > change/increase it, but apparently it does so for me. In my case it > wouldn't really be an issue, except it makes me unsure e.g. whether 2k > frames are guaranteed to handle standard 1.5k payloads. > > [docs] > https://www.kernel.org/doc/html/latest/networking/af_xdp.html?highlight=headroom > > Thanks > --Vladimir >
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