Re. Davicom DM9102A Network Problems

Christian Pellegrin chri at
Thu Aug 1 00:11:24 EST 2002

On Wed, 31 Jul 2002, Howard Gray wrote:

> Howard Gray wrote....
> >> How can the tulip driver work with the DM9102A at all if the transmit
> >> buffers are not guaranteed to be correctly aligned ?
> But my question still remains: How can I get a double word aligned transmit
> buffer using the network core's sk_buff mechanism ? If I can't do that I'll
> have to rewrite the driver to use use my own aligned buffers and copy the
> sk_buff data to them. It's a pity because then it doesn't make much sense to
> follow that with a DMA transfer....

>From Alex Zeffertt mpc860sar.c (in this case 16-byte aligned, just change
to 16 to 4 and 15 to 3):

        // Allocate a socket buffer
        newskb = dev_alloc_skb(mtu_ + 15);

        if (newskb) {
          // Make sure that newskb->data gives a burst-aligned
          // pointer (divisible by 16)
          if ((len = (ulong)newskb->data & (ulong)0x0f)){
            skb_reserve(newskb, 16 - len);


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