> If you were hoping that TCP checksums would protect against (say) DMA
 > errors between the network device and the stack itself, that
 > protection is disabled by off-load.  The trade-off you get is not
 > having to waste CPU time looking at every byte against the
 > unlikelihood of such (system design) errors.

So does this argue for having a supported mechanism for disabling checksum
offload?  I ask because we were recently talking about how to revise dladm
to indicate whether capabilities like checksum offload are supported on a
given link, and at the time it wasn't clear to me that having a facility
for disabling capabilities was a good idea.

My concern was that having a first-class mechanism for disabling them
would be tantamount to saying that all possible combinations are supported
-- but I'm not convinced that's feasible.  Further, I believe for most
capabilities (e.g., LSO or MDT), you'd only want to disable them as a
workaround for a bug or as a debugging aid, for which /etc/system seems to
have the appropriate level of "skank".

-- 
meem
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