Re: Ethtool : PRBS feature

[Andrew Lunn <andrew@lunn.ch>]

> Looks like they are different derivations of the polynomial for the
> given pattern. For example PRBS11 is 1 + x^9 + x^11

802.3 section "72.6.10.2.6 Training pattern" agrees with you.

, but PRBS11_0 is 1
> + x^5 + x^6 + X^10 + x^11. That is one thing to think about. When we
> say PRBS7 the assumption is we are all talking about 1 + x^6 + x^7 for
> the polynomial.

I could be missing it, but i could not quickly find PRBS7 in the
standard!

> We may want to have that clearly recorded somewhere so
> there isn't any confusion on which polynomials we are using for this
> testing as there is always a risk that somebody is playing with
> bleeding edge hardware and ends up defining a PRBS polynomial
> differently than what is expected.

I would probably give a reference to 802.3, at least for standard
tests. If a vendor has made up their own test sequences then yes,
there needs to be a clear definition of what it is.


> I almost wonder if we couldn't
> define the sequence as a bitmap instead of an enum with each bit
> representing which fields are in the sequence.

Not everything is a polynomial. Look at SSPQR, 120.5.11.2.3 SSPRQ test
pattern.

	Andrew