freebsd stable - Aug 2008 - HEADS UP: E1000 networking changes in STABLE/7.1 RELEASE

There is a change that has been in the STABLE tree for a few months,
but many might have missed it,
its an important change to note and possibly for some prepare for with
the 7.1 RELEASE.

There is a new E1000 network driver, igb, which supports two family of
adapters so far: the
82575 and the new 82576.  In FreeBSD 7 the support for 82575 was in
the em driver, however
due to support issues across all the OS's we do drivers for, the
decision was made to split the
newer drivers off from those before. There are big differences in the
register set, and in things
like the descriptor format that made this expedient.

I made the support for the 82575 available very early in FreeBSD,
earlier even than Linux so
that certain vendors could have a working driver early. At first I
thought to avoid splitting the
driver, but support issues are going to make that impractical. So
there is a split, its been in
HEAD since Febuary, and now 7.1 will release with this change.

What this means is that if you have 82575 adapters in a system they
are going to change
from being 'emX' to being 'igbX', in the RELEASE the install
kernel
will have both drivers
in it, but on an upgrade path, or using a set of scripts that get
postinstalled you need to
be ready to make this change.

How can you tell if you have such a device: Simple, use pciconf, there
are only 3 ID's
that are effected:  0x10A7, 0x10A9, and 0x10D6.

If you have questions feel free to email me.

Cheers,

Jack Vogel
Intel Lan Access Division

On Wed, Aug 13, 2008 at 8:13 PM, Paul <paul@gtcomm.net>
wrote:
> Hi Jack.  Will the em driver ever support the multiple hardware queues of
> the 82571 or are we just stuck with the standard em driver?
> Has there been any significant change in the em driver itself ?
> I have a feeling that the 82571 should be in the igb driver but for some
> reason it isn't. I am curious because we have a LOT of 4 port 82571
PCI-E
> cards and they are not cheap.  :]
Hey Paul,

   You are right, quad port cards aren't cheap, Intel has sold them
even back in a
PCI-X based system. And the one you are talking about was released since I
have been in this job, so pretty new :) However, they will never
support multiple
queues, the reason being that in order to do this you need multple MSI vectors,
in other words, MSIX. Still, they are very handy, they do support MSI, but just
one per interface.  Oh, and I debated about where to make the cutoff line on the
em/igb split and decided the best thing to do was to follow Linux. The biggest
difference between the two drivers is that those in the igb use a
different descriptor
format, called 'advanced descriptors'.

   The split does NOT mean that em is now fixed. Quite the contrary,
the em driver
that was just MFC'd into STABLE has support for what I think is going to be
the
coolest new consumer adapter out there, called 82574, code name Hartwell, and
also for ICH10. Both these two new interfaces have IEEE 1588 Precision Time
Protocol support, something that is becoming important for networked multimedia
applications. Oh, and Hartwell is the first adapter in the em driver
that actually
does multiqueue, although in a limited fashion, it does MSIX. This
adapter is made
at a lower cost point, but it has really nice features. I only wish
the new motherboard
that I bought had them rather than ICH9 but oh well :) I predict they
are going to
be selling like hotcakes before the end of year.

I will continue to share fixes between the em and igb drivers as they
are applicable.
I still think a real legacy driver for the oldest adapters would be a
good idea, just so
they don't get broken by new development, with as many as we support
regression
testing is already not being done adequately. I just have not had time
to think about
this yet, it may be coming, it would probably be for everything that
was not PCI Express.

Hope the info was helpful, I'm always happy to answer questions,

Jack

Hi Jack,

Thanks for this and for the concise pciconf line.  We use em (soon to
be igb) interfaces extensively at work.

Best,
George