On Wed, 2011-12-07 at 11:21 -0500, Mark Lord wrote:

On 11-12-06 12:45 PM, Ben Hutchings wrote:

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On Tue, 2011-12-06 at 07:44 -0500, Mark Lord wrote:

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On 11-12-05 10:18 AM, Ben Hutchings wrote:

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On Mon, 2011-12-05 at 09:41 -0500, Mark Lord wrote:

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If this hardware recognises specific protocols and works out the offsets
itself, then you must claim NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM instead.

Yeah, the hardware seems to understand quite a few protocol formats.
Okay, so I'll claim the protocol-specific flags in net->hw_features.

But what do I use in net->features?
The exact same protocol flags,
or the generic NETIF_F_HW_CSUM | NETIF_F_RXCSUM ones?

You set the flags for features that are actually being implemented!

But do set NETIF_F_RXCSUM in both places.  The network stack doesn't
know or care exactly what protocols you can do RX checksum validation
for, so there is only one flag for this.  Only the TX checksum
generation features have to be distinguished.

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The set_features() function also has to test for flags
to know what to do.  Should it test specific protocol flags,
or just the generic two ?

Think it through.

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Heh.. my thinking side says to use the exact same protocol-specific flags
in both "hw_features" and "features", and therefore check for those flags
inside the "set_features()" function.

Right.

But that's not what earlier versions of this driver did,
and nor what the vendor's driver does.
Those versions all mix the protocol-specific and generic flags.

The in-tree driver doesn't seem to have ever enabled checksum offload
features.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.