Re: [PATCH 01/04] Adding cipher mode context information to crypto_tfm

[James Morris]

On Thu, 10 Feb 2005, Fruhwirth Clemens wrote:

> Why should I pass the first thing of size X as scatterlist, and the
> second thing of size X as linear buffer? 
> 
> I could do that. It would be reasonable, because tweaks are more likely
> to be generated than transmitted, read or whatever. But what for shall I
> narrow the interface? I could also pass a linear mapped buffer as
> scatterlist. This doesn't cause any overhead.
> 
> And switching to a more specific interface would just delay a solution
> of the inherent limitations of kmap's. I guess it will take another half
> year until the next guy stumbles across this (totally undocumented!)
> problem. Why are you pushing to ignore this problem?

What problem?

All you need is the two existing kmaps, for simultaneous processing of 
input & output data at the page level.

The tweak is linearly generated data fed into this process.  It does not 
need to be kmapped.  It is not discontiguous.  There is no need for a 
third or Nth scatterlist.

Making a generic N-way scatterlist processor is pointless overengineering,
causing new problems with non-trivial solutions, for no benefit
whatsoever.


- James
-- 
James Morris
<jmorris@xxxxxxxxxx>

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