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ix(4): fix rss hashing on big endian archs
On Wed, Apr 22, 2026 at 10:42:31AM +0200, Claudio Jeker wrote:
> On Wed, Apr 22, 2026 at 01:08:54PM +1000, David Gwynne wrote:
> > i noticed that packets seem to be hashed differently by ix(4) and the
> > network stack on sparc64. the diff below seems to fix it, and it still
> > works as expected on arm64.
>
> How did you notice this?
i was doing a single fast tcp transfer while looking at stuff in systat,
and noticed that ix had interrupts firing on two sets of rings instead
of one like i expect. txq and rxq kstats confirmed the tx and rx
packets were going to different ring indexes.
if you want a clearer indicator, i could add a counters to the tcp stats
that says whether the flowid in rx packets matches the flowid on the tcp
pcb.
> > ok?
>
> Now this screams for bus_space_write_raw_4() but I see that the macro zoo
> does not make this a good option.
>
> I would expect this to be a le32toh() so we end up with htole32(le32toh())
> combo but for all archs we care htole32(x) == le32toh(x) so it really is a
> bikeshed.
i can use do this.
> OK claudio@
>
> Are ixl and ice affected as well?
i havent moved on to looking at ixl yet and i dont have any ice.
>
> > Index: if_ix.c
> > ===================================================================
> > RCS file: /cvs/src/sys/dev/pci/if_ix.c,v
> > diff -u -p -r1.223 if_ix.c
> > --- if_ix.c 26 Feb 2026 23:38:10 -0000 1.223
> > +++ if_ix.c 22 Apr 2026 03:04:16 -0000
> > @@ -3061,8 +3059,13 @@ ixgbe_initialize_rss_mapping(struct ix_s
> > }
> >
> > /* Now fill our hash function seeds */
> > - for (i = 0; i < 10; i++)
> > - IXGBE_WRITE_REG(hw, IXGBE_RSSRK(i), rss_key[i]);
> > + for (i = 0; i < nitems(rss_key); i++) {
> > + /*
> > + * twist the words so the rss key will be handled
> > + * as bytes regardless of the hosts endianness.
> > + */
> > + IXGBE_WRITE_REG(hw, IXGBE_RSSRK(i), htole32(rss_key[i]));
> > + }
> >
> > /*
> > * Disable UDP - IP fragments aren't currently being handled
> >
>
> --
> :wq Claudio
ix(4): fix rss hashing on big endian archs