[lwip-devel] [bug #49914] lwip_sendmsg uses PBUF_REF pbufs

[Joel Cunningham]

Follow-up Comment #12, bug #49914 (project lwip):

I'm curious to see how the Linux driver for that hardware handles the
alignment.  I'm somewhat familiar with Linux socket buffers and did a little
digging.

Looks like there is a default alignment applied in alloc_skb() (__alloc_skb):
http://lxr.free-electrons.com/source/net/core/skbuff.c#L203

There is also evidence here that the driver can't specify arbitrary alignments
for TX buffers and must handle a mis-match by making a copy:

http://www.gossamer-threads.com/lists/linux/kernel/1108227

Any chance you can look at the Linux driver?

Maybe we could have a feature where PBUF_RAM alignment could be specified
during compilation.  This might be tricky if there are multiple netifs with
different requirements

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