Re: [lwip-users] lwipopts: TX_SINGLE_PBUF

[Simon Goldschmidt]

David Gauchard wrote:
> There are two comments in opt.h:
> "@todo: TCP and IP-frag do not work with this, yet:" next to 
> LWIP_NETIF_TX_SINGLE_PBUF
>  "Try to create unfragmented TCP packets" next to TCP_OVERSIZE
> 
> Is there anything planned to get rid of the "todo" and "try" in the above
> comments ?

The whole point of LWIP_NETIF_TX_SINGLE_PBUF was that the stack tries to do its 
best.
A driver should still be prepared to get chained pbufs and copy them into one 
piece.

LWIP_NETIF_TX_SINGLE_PBUF should be a performance optmization to e.g. prevent 
copying
data into a chained pbuf when we know it has to be copied again later to create 
a pbuf
in one piece. Where this doesn't hurt much, I don't currently see a problem to 
make the
driver do this.

You should be able to just use pbuf_clone() if p->next != NULL.

Of course I'm open to fix the possibly remaining chained pbuf issues, but I 
can't
afford the time for this currently.


Simon