linux-kernel - Re: [PATCH v7 12/14] crypto: iaa - Add support for deflate-iaa compression algorithm

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Message-ID: <6ba5b58f637e3ec8c4b00e407e18dd426db6086f.camel@linux.intel.com>
Date:   Sat, 22 Jul 2023 12:14:28 -0500
From:   Tom Zanussi <tom.zanussi@...ux.intel.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     davem@...emloft.net, fenghua.yu@...el.com, vkoul@...nel.org,
        dave.jiang@...el.com, tony.luck@...el.com,
        wajdi.k.feghali@...el.com, james.guilford@...el.com,
        kanchana.p.sridhar@...el.com, vinodh.gopal@...el.com,
        giovanni.cabiddu@...el.com, linux-kernel@...r.kernel.org,
        linux-crypto@...r.kernel.org, dmaengine@...r.kernel.org
Subject: Re: [PATCH v7 12/14] crypto: iaa - Add support for deflate-iaa
 compression algorithm

On Sat, 2023-07-22 at 13:23 +1200, Herbert Xu wrote:
> On Mon, Jul 10, 2023 at 02:06:52PM -0500, Tom Zanussi wrote:
> > 
> > Because the IAA hardware has a 4k history-window limitation, only
> > buffers <= 4k, or that have been compressed using a <= 4k history
> > window, are technically compliant with the deflate spec, which
> > allows
> > for a window of up to 32k.  Because of this limitation, the IAA
> > fixed
> > mode deflate algorithm is given its own algorithm name, 'deflate-
> > iaa'.
> 
> So compressed results produced by this can always be decompressed
> by the generic algorithm, right?
> 

Right.

> If it's only when you decompress that you may encounter failures,
> then I suggest that we still use the same algorithm name, but fall
> back at run-time if the result cannot be decompressed by the
> hardware.  Is it possible to fail gracefully and then retry the
> decompression in this case?
> 

Yeah, I think that should be possible. I'll try it out and add it to
the next version.  Thanks for the suggestion!

Tom


> Thanks,