Re: [ECOS] Porting of PPP to the eCos operating system.

["Phil Dempster" <p_dempster at yahoo dot co dot uk>]

In the absence of any other replies I'll throw in my tuppence worth:

> The TCP/IP stack implemented under eCos is a port of the OpenBSD
> TCP/IP  stack. It seems therefore to me that the PPP, which will require
> the least  effort to port will be the OpenBSD PPP

I concur, with the proviso that it is going to be quite expensive in terms
of memory footprint.

> TCP/IP code uses the net interface and the pppd daemon uses the tty
> line discipline...
> ...The Redhat procedure for integrating network drivers
> into eCos does not seem to cope very well with this. It only allows the
net interface.

The main significance here is that, in BSD,  the datapath code is kept
within the kernel.  In eCos, there is not the same distinction between
kernel space and userland.  It is desirable, though not essential, to
present the same POSIX-style interface to pppd in order to ease the porting
process.

> Instead it seems to me a better idea to implement the PPP driver as
> a device driver for the devfs pseudo file system (/dev) in eCos. This
> driver will be a layered driver on top of some transport driver (a serial
> driver).

I agree that it should be a devfs device driver.  Note however that it need
not just sit on top of a serial driver; it could also attach to a network
driver (for example RFC2864 Multiprotocol Encapsulation over AAL5).

> Drivers for the devfs pseudo file system does not support ioctl. It should
> not be very complicated to implement this support though.

I'm surprised that it does not. Maybe it's still on the todo list.

> I would very much like to have response to the above. Objections etc.

It seems that you've considered this fairly thoroughly.  I'm afraid I don't
have sufficient familiarity with the eCos BSD port to give any more
constructive feedback.

Cheers,
Phil.