[U-Boot] Ethernet HW loopack test

[Guy Morand]

> -----Original Message-----
> From: Wolfgang Denk [mailto:wd at denx.de]
> Sent: mardi 21 décembre 2010 16:04
> To: Guy Morand
> Cc: u-boot at lists.denx.de
> Subject: Re: [U-Boot] Ethernet HW loopack test
> 
> Dear Guy Morand,
> 
> please restrict your line length to approx 70 characters or so.

Yes sorry in my company they use the great M$ outlook 2010, I'm not very familiar
and apparently it does not know about "automatic carriage return" ... 
Adding ">" to the eplies was already a Big mess ... I'll do my best in the future!

> 
> In message
> <A91D8217D6A8B240A79EBEE98176B19B298B1D2069 at PRISM.telecontrol.loc
> al> you wrote:
> >
> > I'm trying to write an U-Boot command to ping the other interface on
> > my pla tform. This is to test the hardware at production, the ping
> > must hit the wi re. I got deeply inspired from this patch:
> > http://lists.denx.de/pipermail/u-boot/2005-March/009317.html
> 
> I hope you also ready my comments.  These still apply.
> 
> > What changes is that I really want to ping the other interface with a
> > cross  cable and not using a special "home made" device ... The
> > problem is when I  send the ping, it is the same interface that
> > answers (the one that sent th e ping), this is not what I want. I
> > thought by changing the destination MAC  address in the packet and
> > initializing it, the other interface should answ er by itself. Actually this is not
> the case...
> ...
> > I checked with Wireshark, the packet is correctly build. Maybe my
> > approach is flawed ! Or maybe do you have another way to perform that
> kind of test ?
> 
> You a run into a number of very basic limitations here.
> 
> First, U-Boot has, so far, no clean device model yet. In your case this means
> that we can enable only one Ethenret interface at a time.
> When you enable one interface (to send a packet), all other interfaces are
> shut down and disabled, so they will never be able to see the packet, even if
> it arrives as intended.  We have been discussing improvments in this area in
> the past, but nothing got implemented or even designed yet.
> 
> Second, U-Boot is strictly single-tasking. Even if we had a better driver
> interface so we were able to "open" two network interfaces simultaneously,
> we have no infrastructure in place to run independend "send" and "receive"
> tasks.
> 
> If local loopback tests are not sufficient, you will probably find it easiest to
> perform such testing using an external test machine with two network
> interfaces.
> 
> Best regards,
> 
> Wolfgang Denk

Thanks for your reply, this is more or less what I thought in my bath yesterday
evening !

> 
> --
> DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
> It's hard to think of you as the end result of millions of  years  of evolution.

Regards,
Guy Morand