Hi David, On 09/23/2016 07:43 PM, David Miller wrote: > From: Eric Nelson <e...@nelint.com> > Date: Fri, 23 Sep 2016 10:33:29 -0700 > >> Since the hardware requires longword alignment for its' DMA transfers, >> aligning the IP header will require a memcpy, right? > > I wish hardware designers didn't do this. > > There is no conflict between DMA alignment and properly offseting > the packet data by two bytes. > > All hardware designers have to do is allow 2 padding bytes to be > emitted by the chip before the actual packet data. >
Andrew Lunn pointed out that the hardware does support this, and I just pushed a patch for the vendor kernel to the meta-freescale mailing list: https://lists.yoctoproject.org/pipermail/meta-freescale/2016-September/019228.html > Then the longword or whatever DMA transfer alignment is met > whilst still giving the necessary flexibility for where the > packet data lands. > Right. A relatively small change fixes things right up. Many thanks to Andrew for pointing this out and Russell for providing the basis for my patch. I'll re-work this for the up-stream kernel when I get out from under a couple of unrelated things.
