Re: [PATCH 00/23] Subject: [PATCH net-next 00/23] net/hpe: add HPE Slingshot NIC drivers

[Doug Ledford]

On 11/1/26 5:35 PM, Andrew Lunn wrote:
>> I'll see how fast I can get that done.  But "the bare minimum" is going
>> to be more than you are accustomed to.  This hardware does not receive
>> Ethernet packets using MAC address like normal Ethernet hardware.  It
>> uses a special portal table entry that filters in the Ethernet packets.
>> It has the ability to have different filters that receive different
>> Ethernet packets and so sorts them before the driver ever sees them.
> 
> Can you add a single portal entry which matches everything? Or matches
> a single MAC address? KISS.

That's a complex question, and one which I need to go talk to one of the
hardware engineers about.  It also varies based upon your meaning of
"everything".  If, by everything you means essentially promiscuous mode,
then that's not a good idea.  On the fabric there is Ethernet traffic,
but there is also Slingshot traffic.  They use totally different frame
types.  If you truly go for "everything", you'll get Slingshot traffic
along with Ethernet traffic and you'll be throwing away tons of garbage
and generally wondering what's going on.  If by "everything" you just
mean "all Ethernet traffic on a single portal entry", that's when I have
to go talk to the hardware engineers.  They have different lists they
use for Ethernet and I can't say for certain that the hardware will
allow not using those lists.  For instance, one of the lists might be
specifically for packets that have been fragmented and if you don't use
that list for those packets it may not receive them at all.  That's when
I have to go verify things with the hardware engineers.

> You can then add on the complexity of adding MAC addresses to the
> table in later patchsets.

The card has a burned in MAC address.  I wasn't trying to say it
doesn't.  I was pointing out that how the hardware determines what to
receive is not by just putting recv buffers on a queue and turning on
receive mode and letting your MAC address pull them in.  It's more
complex due to the portals table entries.

I did have the AI do a full analysis of what you requested.  A bare
minimal driver.  It passed this back (just giving the summary, not the
full report):

Estimated total for a C2-only, PF-only Ethernet series:

ss1 about 19–20k
SL about 15–20k
headers about 15–20k
That gives roughly 50–60k lines, or about 65k if C1 support stays.

The AI did mention that some of these are estimates and not real
measurements, so take it with a grain of salt.  If you'd like to see the
full report I can provide it.

-- 
Doug Ledford <doug.ledford@xxxxxxx>
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