Re: [ECOS] Ethernet driver for linux synthetic target available

["Nikolay V. Pyatkov" <npyatkov at usa dot net>]

On Friday 09 August 2002 04:21 am, you wrote:
> "Nikolay V. Pyatkov" wrote:
> > > Or even better the generic TUN/TAP driver which obsoletes ethertap.
>
> 100% ACK. Yet another kernel module for functionality that already
> exists is a bad idea. Especially because it'll probably stop compiling
> in a few weeks when the Linux kernel hackers change one of their
> internal kernel APIs again... :-(
>
> > > I thought of converting that to ecos/synthetic but got confused by what
> > > can or cannot be safely called from it (execve,blocking read,etc)
> >
> > Yes, that was one of the reasons I did not use TUN.
>
> The blocking problem might be tricky (well, you could always use
> O_NONBLOCK but then you'd have to poll). How do you solve it with your
> driver?
>
> Another possibility would be aysnchronous IO and mapping the SIGIO from
> Linux to an eCos interrupt. Interestingly, synth_intr.c already seems to
> provide some kind of support for that, but it doesn't look like it's
> fully implemented (it talks about an IO auxiliary that doesn't seem to
> be implemented anywhere). Can anybody comment on that?
>
> > Also it requires the
> > character device to control its network interface. But the main reason is
> > I need several ecos targets running simultaneously and talking to each
> > other and the host.
>
> So use one TUN/TAP per eCos target and enable IP forwarding on your
> Linux box or attach the interfaces to the Linux bridge. No need to
> reinvent the wheel. ;-)
>
> Martin

Well, the ecos part of the driver does not care about the nature of the linux 
character device interface. With a slight modification it could be used with 
tun, ecxept right now it can't control network device of the tun.

I'll apreciate if anybody sends me a script to install several tun drivers on 
the same pc. I will modify the driver to work with that setup.

Nikolay


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