Re: [PATCH v4 3/3] public/io/netif.h: document new extra info for passing hash values

[Ian Campbell <ian.campbell@citrix.com>]

On Fri, 2016-01-08 at 16:26 +0000, Paul Durrant wrote:
> > -----Original Message-----
> > From: Ian Campbell [mailto:ian.campbell@citrix.com]
> > Sent: 08 January 2016 16:06
> > To: Paul Durrant; xen-devel@lists.xenproject.org
> > Cc: Ian Jackson; Jan Beulich; Keir (Xen.org); Tim (Xen.org)
> > Subject: Re: [PATCH v4 3/3] public/io/netif.h: document new extra info
> > for
> > passing hash values
> > 
> > On Thu, 2016-01-07 at 13:05 +0000, Paul Durrant wrote:
> > > 
> > >  /*
> > > + * Hash types. (See NETIF_CTRL_TOEPLITZ_FLAG_* definitions above
> > > + * for more information).
> > > + */
> > > +#define XEN_NETIF_HASH_TYPE_NONE        0
> > > +#define XEN_NETIF_HASH_TYPE_IPV4        1
> > > +#define XEN_NETIF_HASH_TYPE_IPV4_TCP    2
> > > +#define XEN_NETIF_HASH_TYPE_IPV6        3
> > > +#define XEN_NETIF_HASH_TYPE_IPV6_TCP    4
> > 
> > Should these be TYPE_TOEPLITZ_FOO? I suppose there are other possible
> > TCPv4
> > hashes for example.
> 
> I didn't consider that possibility of having multiple hashing schemes in
> operation at the same time, but I guess someone may want such a thing at
> some point.

Hrm, yes, I suppose IPV4_TCPa and IPV4_TCPb would be somewhat mutually
exclusive.
[...]
> > 
> > The control side (previous patch) has a toeplitz specific mechanism,
> > with
> > individual hash bits with it, whereas this is presented more as a
> > generic
> > hash mechanism with specific bits corresponding to toeplitz hashes.
> > i.e. NETIF_CTRL_TOEPLITZ* vs XEN_NETIF_EXTRA_TYPE_HASH. Seems like a
> > wrinkle, but I'm not sure if its an important one.
> > 
> 
> ...if perhaps I make the extra type XEN_NETIF_EXTRA_TYPE_TOEPLITZ_HASH.
> That would leave things more open for someone else adding an extra type
> for another hash and needed a slightly different format/set of flags.

I'm happy with that (and think it's probably a good idea despite the
comment above).

Ian.


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