[lwip-users] Re: [lwip] Recent change in pbuf.c

[leon . woestenberg]

Hello David,

could you please indicate what part of the link header is prepended by your
Ethernet chip automatically?

Jani's patch looks OK to me.

Leon Woestenberg.


There was a recent change in pbuf.c by jani which says: "fix pbuf_alloc for
layer PBUF_LINK". This change has caused some problems for me and I want to
explore why.

In my ethernet driver I am using PBUF_LINK when allocating pbufs for the
receive buffers. This recent change will reserve bytes in the front of the
pbuf, presumably for a link-level header. However, the ethernet chip will
be putting a link-level header in the packet already. So I would claim that
the offset for PBUF-LINK should be 0 (which it was before it was changed).
Now, I could change my allocation to PBUF_RAW, but I would claim that would
wrong.


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