[ECOS] rattler PB

Slawek sgp@telsatgp.com.pl
Fri Dec 19 14:38:00 GMT 2003


Nick Garnett wrote:

> "Slawek" <sgp@telsatgp.com.pl> writes:
> 
> > Andrew Lunn wrote:
> > 
> > > On Thu, Dec 18, 2003 at 09:22:47AM +0100, alix t wrote:
> > > > We try to develop applications with goahead web server
> > > > and other network services on rattler card , but our
> > > > applications often crash.
> > > > So we want first validate ethernet and IP stacks.
> > > > I think to send very large packets is a good test to
> > > > validate ethernet stack.
> > > 
> > > Its not a realistic test. I doubt any application will use such large
> > > IP packets. UDP has a maximum packet size of around 4Kbytes. TCP will
> > > generally use either around 800 bytes or around 1500 bytes depending
> > > on if MTU discovery is being used. 
> > > 
> > > Only a custom application which is not using UDP or TCP can generate
> > > such big IP packets. Typically this would be for connecting super
> > > computers together using HIPI interfaces. Thats why IPv6 has a jumbo
> > > packet which can be bigger than 64Kbytes. 
> > > 
> > > I suggest you try more realistic tests.
> > 
> > Keep in mind that he has tried to send big packets *to* the device,
> > *not* write a special program for the device which failed when
> > sending those.
> > 
> > If such packets causes the device to crash, then the *final* product
> > could be *crashed* as well, by accident or intentionally.
> 
> I usually test any ethernet interface I am working on by flood
> pinging it with large packets. The TCP/IP stack is quite robust enough
> to handle this. Of course there may be issues in the device driver,
> and this sometimes causes the stack to run out of mbufs. It is very
> unlikely that doing this would actually cause a crash.


Well, I hope it would not crash as I plan to use eCos in one more
project soon and I'd need Ethernet support there.


The cite below doesn't look promising...


alix t> "warning: eth_recv out of MBUFS" and after card has
alix t> strange behavior, ping often fail and BUS Error or
alix t> Illegal instuction appears.


Well, anyway. I'm going to make some tests of my own.
Maybe it's target specific or so.


-- 
Slawek



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