[linux-dvb] Re: DVB-CI question

[Andrew de Quincey <adq_dvb@lidskialf.net>]

On Friday 26 March 2004 15:14, Klaus Schmidinger wrote:
> Andrew de Quincey wrote:
> > ...
> > Its just it makes the driver's IO routines _really_ complex, as they have
> > to deal with multiple connections, multiple slots, the possibility that
> > the CAM can be yanked out by the user at any time, and lots of other
> > things. There is a LOT of complex locking involved to ensure it can't
> > break.
> >
> > Add to that the fact that each de-fragmented packet can be up to 65536
> > bytes,
>
> Strange, from what I know a TPDU can be at most 2048 byte long...
>
> Maybe you could take a quick look at VDR/ci.c and let me know whether
> the data VDR exchanges with the CI already consists of the "fragements"
> you're referring to.

From looking at it, you're talking about transport layer fragmentation based 
on T_DATA_LAST/T_DATA_MORE.

I'm talking about the layer below that: Each of those TPDU fragments can be 
further re-fragmented into multiple link layer packets when they're actually 
written to the CAM. Link layer packets can be up to 65535 bytes. I suppose I 
could use knowledge of the fact that the higher layers will never send 
anything more than 2048 bytes to optimise that though.


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