GT10_PCI_EXPRESS_n

According to the Xilinx documentation the GT10_PCI_EXPRESS_n primitive
is only "supported for Virtex-II Pro X but not for Virtex-II or
Virtex-II Pro". Does this mean that you can't use the Virtex-II Pro in
a PCI-Express application? Is this related to the electrical idle, or
are there other reasons?

Thanks
Petter

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Hello,

> According to the Xilinx documentation the GT10_PCI_EXPRESS_n
> primitive is only "supported for Virtex-II Pro X but not for
> Virtex-II or Virtex-II Pro".

The GT10_PCI_EXPRESS_n primitives are based on the GT10
primitive that is only available in Virtex-II ProX.  The
protocol specific primitives are "convenience macros"
that use the transceiver primitives and have all the
attributes set for the specific protocol, so you don't
need to figure it out yourself.

In Virtex-II Pro, you can use the GT primitive, and there
are some "convenience macros" for ethernet, fibre channel,
and infiniband.  However, there isn't one for PCI Express,
so you would need to use the GT primitive and then set
all the attributes to get the desired result.

Your next question would probably be, "Why?" and I'm not
sure so I'll file an enhancement CR on this issue.  I suspect
it is due to the Virtex-II Pro library being developed before
PCI Express specifications were final.  (And this is not the
case for Virtex-II ProX...)

> Does this mean that you can't use the Virtex-II Pro in
> a PCI-Express application?

No.  You can use Virtex-II Pro for PCI Express, and we do!
If you want to read more about it, you can check out our
IP datasheet for the PCI Express endpoint core, at:

http://www.xilinx.com/systemio/pciexpress/index.htm

> Is this related to the electrical idle, or are there
> other reasons?

Unrelated.

Hope that helps,
Eric

Eric Crabill <eric.crabill@xilinx.com> writes:

> No.  You can use Virtex-II Pro for PCI Express, and we do!

This was my impression until I was confused by the discovery of the
GT10_PCI_EXPRESS_n primitive. Thank you for the clarification.

Petter
-- 
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?