[Rpcemu] Risc OS 4.39 hangs on networking

Theo Markettos rpcemu at markettos.org.uk
Fri Mar 27 16:20:56 EDT 2009

On Thu, Mar 26, 2009 at 10:53:11PM +0100, Gillian Seed wrote:
> Good news everybody.
> What? AppleTalk! Yes off course RISC OS 4.39 has AppleTalk in ROM and
> 4.02 hasn't. So I unplugged the damn thing and  EtherRPCEm works fine!
> I successfully connected to internet with it without any problems.

That's excellent news!

> It looks like that AppleTalk doesn't behave itself or that EtherRPCEm
> isn't robust enough.

So I suppose the question is... does the TUN/TAP stuff do anything different
with non-IP protocols?  I wouldn't have thought it would, but you never

It looks like AppleTalk multicast might be the problem.  Apparently it uses
it extensively for naming and advertising services, issuing up to 20
requests at startup.

I found some old (2001) stuff about Linux TAP only supporting AppleTalk if
the multicast flag is enabled in tap.c (which I assume is therefore a kernel
compilation option).  It's not quite clear what the current situation is,
but I've found a plenty of comments that suggest people are having possibly
multicast-related problems with random software.  Such as this:

However, it's quite possible that what it needs is multicast support in
RPCEmu's TAP code.


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