Re: [lwip-users] Socket-API and memory allocation.

[Jonathan Larmour]

address@hidden wrote:
> Hello.
>
> I'm using LwIP 1.2.0 and I've run into some problems when it comes to
> the bulk of parameters that tunes LwIP when it comes to memory consumption
> and performance. The current problem is if there is any document
> describing the relation between all the parameters that are defined in
> opts.h.

Only the comments in opts.h really. The code in CVS has some new 
consistency checking in it, although there's only so far that can go.

> Another problem I have is how LwIP handles allocation errors (or rather
> DOESNT handle them). For example when using the Socket API and calling
> send(), the code ends up at the following point:
>
> send() (or lwip_send()) ends up calling netcon_write().
> netcon_write() first allocates a API_MSG, and seem to handle any failure
> to do so in a good way. However, later in netcon_write() the following two
> lines can bee seen:
>
>     api_msg_post(msg);
>     sys_mbox_fetch(conn->mbox, NULL);    
>
> api_msg_post() begins with allocating a TCPIP_MSG, but if this fails,
> conn->mbox is never ever signaled, causing the application doing the
> send() to lock up for ever.

Yes, this was a known issue, and is fixed in CVS by allocating the 
TCPIP_MSG on the stack. However if you need to stay with 1.2.0, then all 
you can do is increase the number of TCPIP_MSG's.

If you want to move to using the code in CVS, there's a wiki that describes 
the changes required at http://lwip.scribblewiki.com although personally 
I've never been able to get that site working (I know what the issue is, 
and reported it to their admins, but they haven't done anything about it).

Jifl
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