On Wed, Sep 28, 2016 at 10:14:52AM -0700, Eric Nelson wrote: > Thanks David, > > On 09/28/2016 09:42 AM, David Laight wrote: > > From reading this it seems that the effect of FEC_RACC_SHIFT16 is to > > add two bytes of 'junk' to the start of every receive frame. > > That's right. Two bytes of junk between the MAC header and the > IP header.
That's wrong. FEC_RACC_SHIFT16 adds two bytes to the _beginning_ of the packet, not in the middle of the packet: 7 RX FIFO Shift-16 SHIFT16 When this field is set, the actual frame data starts at bit 16 of the first word read from the RX FIFO aligning the Ethernet payload on a 32-bit boundary. NOTE: This function only affects the FIFO storage and has no influence on the statistics, which use the actual length of the frame received. 0 Disabled. 1 Instructs the MAC to write two additional bytes in front of each frame received into the RX FIFO. *in front* of the frame - that's before the Ethernet header. Not between the ethernet and IP headers. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.