Re: [lwip-users] pbuf handling / possible bug?

[address@hidden]

Michael Steinberg wrote:
> One of the "services" which are running
> here is a Precision-Time-Protocol slave clock. This protocol relies on
> hardware time stamping of arrival or transmit of so called "event"
> messages.

I'm aware of the difficulties a PTP slave (or even bridge 
implementation) faces with lwIP. I think these would be best met by 
adding custom members to struct pbuf that are initialized to 0 by 
pbuf_alloc. The reason we haven't done so yet is that "sizeof(struct 
pbuf)==16" fits quite well to small targets. However, having PTP support 
should be a good reason to drop this 16-byte requirement.

I guess having (yet another) define to add custom pbuf members would be 
the way to go here.

However, you wouldn't easily get these flags passed to socket layer, so 
that might not solve your API problem - although netconn API might work 
with some sort of hacked code accessing the netbuf's pbuf flags.

BTW: what kind of PTP stack do you use? I have been searching, but 
alhough PTP seems like a well-documented, small protocol, there doesn't 
seem to be an open source solution for this, or did I miss something?

Simon