Re: [PATCH v5 13/15] crypto: iaa - Add support for default IAA 'canned' compression mode

From: Tom Zanussi
Date: Tue May 30 2023 - 15:50:15 EST

Hi Herbert,

On Thu, 2023-05-25 at 08:37 +0800, Herbert Xu wrote:
> On Wed, May 24, 2023 at 10:58:54AM -0500, Tom Zanussi wrote:
> >
> > Yes, I think you're right.  The reason we did it this way was that
> > we're expecting to add more modes, such as 'dynamic' and/or
> > 'canned-
> > dynamic' etc.
> >
> > But I don't see a reason we couldn't just register them all and
> > have
> > the user choose using the algorithm names, especially if that's the
> > way
> > crypto users expect things to work.
> Are these modes compatible with the deflate algorithm, that is,
> can the generic deflate uncompress the output of these modes and
> vice versa, can these modes uncompress the output of the generic
> algorithm?
> If they're all compatible, then you should just use the "deflate"
> algorithm name and use different driver names to differentiate them.
> But if they're not compatible then the modes should have distinct
> algorithm names.

Canned mode is not compatible with generic deflate. Fixed mode is, but
due to history-window limitations in the hardware, only for buffers <=
4k, or that have been compressed using a <= 4k history window.

So it sounds like we need to use distinct algorithm names, which I'll
add in the next version.



> Cheers,