Message-ID: <4B6FCC47.2030705@crca.org.au>
Date: Mon, 08 Feb 2010 19:33:11 +1100
From: Nigel Cunningham <ncunningham@crca.org.au>
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To: Bill Davidsen <davidsen@tmr.com>
CC: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
       tuxonice-devel@lists.tuxonice.net
Subject: Re: LZO irreversible output?
References: <4B69ECE5.5060505@crca.org.au> <201002032354.11284.rjw@sisk.pl> <4B6A4F07.3090509@crca.org.au> <hkneh9$djl$1@ger.gmane.org>
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Hi Bill.

Bill Davidsen wrote:
> I would hope someone will look at the real problem, though, that LZO
> isn't working properly. I have to assume that either the kernel
> decompress is broken or that the page you have given is invalid, and the
> error lies in the compression.
> 
> It doesn't look as if you are doing something wrong, it looks broken.

I did get hold of Richard Purdie and Nitin Gupta, who were the guys in
the know. We discovered that LZO is expecting decomp_size to be
initialised to the amount of available space when the decompression code
is called, so there was a bug in my testing code. Nitin was talking
about sending a patch to the documentation to make this requirement clearer.

That said, the actual code that TuxOnIce uses does already initialise
the variable to PAGE_SIZE, so it seems that I might just have to run
with the checking code enabled (with this fix) for a while, until the
issue is found.

Regards,

Nigel

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