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Date:      Wed, 22 Mar 2000 07:32:04 +0100
From:      Poul-Henning Kamp <phk@critter.freebsd.dk>
To:        Nick Sayer <nsayer@sftw.com>
Cc:        freebsd-hackers@FreeBSD.ORG
Subject:   Re: md_image compression? 
Message-ID:  <29639.953706724@critter.freebsd.dk>
In-Reply-To: Your message of "Tue, 21 Mar 2000 21:55:39 PST." <200003220555.VAA56886@yoda.sftw.com> 

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In message <200003220555.VAA56886@yoda.sftw.com>, Nick Sayer writes:
>
>I'm sort of thinking in my head about adding the ability for the
>md driver to handle gziped images. md's drvinit() looks like
>the perfect place to do this. if strcmp(type,"md_image_gzip") then
>gunzip the image and so on.
>
>Obviously this trades RAM for disk space. The target implementation
>is the i-opener -> X terminal transmogrification. I think I can cram
>the whole thing into the 16M flash card, and with compression of that
>image, I can cram a lot more. To implement it, I have some questions:
>
>1. Is there a way to de-allocate or otherwise reuse the original
>compressed image after the unzip is finished?

currently not.

>2. What is the best strategy for allocating the output image?
>malloc(9)?

Use the code already in MD which recognizes empty sectors, that
will give you a little bit of compression.

>3. This would effectively add libz to the kernel. 

We actually already have a unzip'er available in the kernel,
the one which was used for unzip'ing a.out executables.

--
Poul-Henning Kamp             FreeBSD coreteam member
phk@FreeBSD.ORG               "Real hackers run -current on their laptop."
FreeBSD -- It will take a long time before progress goes too far!


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