On Fri, 28 May 2021 14:18:33 -0700 Tom Herbert wrote:

quoted

On Fri, May 28, 2021 at 10:44 AM Lorenzo Bianconi [off-list ref] wrote:

quoted

Introduce flag field in xdp_buff and xdp_frame data structure in order
to report xdp_buffer metadata. For the moment just hw checksum hints
are defined but flags field will be reused for xdp multi-buffer
For the moment just CHECKSUM_UNNECESSARY is supported.
CHECKSUM_COMPLETE will need to set csum value in metada space.
 

Lorenzo,

This isn't sufficient for the checksum-unnecessary interface, we'd
also need ability to set csum_level for cases the device validated
more than one checksum.

IMO, we shouldn't support CHECKSUM_UNNECESSARY for new uses like this.
For years now, the Linux community has been pleading with vendors to
provide CHECKSUM_COMPLETE which is far more useful and robust than
CHECSUM_UNNECESSARY, and yet some still haven't got with the program
even though we see more and more instances where CHECKSUM_UNNECESSARY
doesn't even work at all (e.g. cases with SRv6, new encaps device
doesn't understand). I believe it's time to take a stand! :-)

I must agree. Not supporting CHECKSUM_COMPLETE seems like a step back.

I completely agree on it and I want add support for CHECKSUM_COMPLETE as soon
as we decide what is the best way to store csum value (xdp_metadata?). At the
same time this preliminary series wants to add support just for
CHECSUM_UNNECESSARY. Moreover the flags field in xdp_buff/xdp_frame will be
reused for xdp multi-buff work.

Regards,
Lorenzo