Re: [Qemu-devel] qemu networking help

[M. Warner Losh]

In message: <address@hidden>
            Ryan W Smith <address@hidden> writes:
: I'm currently working on a project where we're using qemu to trace  
: information flow through the operating system.  One of the things  
: that we'd like to do is trace network data as it flows through the  
: operating system.  I've been reading through the code, and I've  
: gotten a bit lost.  I gather that slirp is where data comes and goes  
: from the host operating system, but I'm looking for the section of  
: code that sends and receives data from the guest operating system.  I  
: read through the network device code (ne2000.c), and my guess is that  
: the inb and outb functions are used to transfer data to the guest,  
: but I'm not quite certain how that is done.  Is there anything that  
: anyone can point me to that would explain the process of getting data  
: from the networking device to the guest operating system?  Also, is  
: there anything that explains the ne2k networking device a little  
: more, and could explain what all the registers are and how to use  
: them?  Thanks in advance for any help you may offer.

Well, the ne2000 has a shared memory area that the packets live in,
and a i/o port area that signals the host O/S what's going on.

I'd suggest reading the FreeBSD if_ed driver for some more information
about the card.  From it you'll see that the NE2000 has a DS8390
packet engine that does a DMA directly into the shared memory.  The
ds8390 datasheet can be foudn on the network.  You may also find good
comments in the Linux ne.c driver:
        http://www.gelato.unsw.edu.au/lxr/source/drivers/net/ne.c

Warner