[openbeosnetteam] Re: Quick question about the stack

Hi,
we have a special ioctl() that allows to call the control() function of an 
interface module (pppconfig makes use of it).

There are two different module types that the core knows of:
- protocol
- interface
Ethernet is a normal interface module. When loaded it iterates over all drivers 
in
/dev/net
and attaches an ifnet to each device.
The core has two threads for sending and receiving. It starts one pair for each 
registered ifnet.
Driver interfaces (which open() a driver in /dev) can be handled by these 
threads, too. The receiver calls read() and transforms that data into a packet 
and puts this packet into the queue specified in the ifnet. The other one 
write()s all outgoing packets in the ifnet's queue. These threads are used by 
Ethernet.
The functions for creating such a thread are (core.c):
start_tx_thread(ifnet*)
start_rx_thread(ifnet*)
They distinguish between ethernet and other interfaces.
Loopback uses these functions, too, but start_rx_thread() will run a different 
thread function that calls the input() function pointed to by the ifnet 
structure.
PPP does not use any of those functions at all.

You can look into core.c to see the inner workings in detail.

Waldemar

----- Original Message ----- 
From: "Brennan Cleveland" <warriorspot@xxxxxxxxxxxxx>
To: <openbeosnetteam@xxxxxxxxxxxxx>
Sent: Friday, January 09, 2004 7:18 PM
Subject: [openbeosnetteam] Quick question about the stack


Hi,

Im looking over the stack diagram again, and I just want to clarify a
few points.

According to the diagram, the stack is very modular (which is good).
That said, lets use ping for an example.  ping, as an app, only
"knows about" the libnet.so sockets API, and libnet.so interfaces
with the stack driver.  The stack driver interfaces with core, and
core interfaces with the protocol modules.  Are there any violations
anywhere in the code to this modularity?  For example, any case where
code in ping.c makes a call directly to a routine in the net stack
driver, bypassing libnet.so?

Also, where does the ethernet driver fit in?  It looks like the
ethernet module would interact with the driver, which then obviously
controls the hardware...


Thanks,

Brennan

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