Subject: Compressed images?

From: William Jhun <[email-masked]>
Date: Mon, 4 Mar 2002 12:08:03 -0800

I've been looking through the recent linux-mips archives and it seems
there isn't a concensus about where to build compressed ((b)zImage)
images. We have been placing our code under arch/mips/boot/compressed,
though it seems that the latest oss tree doesn't have such a directory,
and the only reference I can find to building a compressed image is in
galileo-boards/ev64120/compressed/.

Should we be placing our boot image compression stuff in our
platform-specific directory? Are most MIPS-based Linux platforms not
using compressed images?

Thanks,
Will

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From: Karsten Merker <[email-masked]>
Date: Mon, 4 Mar 2002 22:31:17 +0100

> platform-specific directory? Are most MIPS-based Linux platforms not

I cannot speak for "most" platforms, but at least the DECstations
and the SGI IP22 (Indy and Indigo2) can only boot uncompressed images
currently, so it does not make sense to build compressed images for
them.

Regards,
Karsten
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From: Ralf Baechle <[email-masked]>
Date: Mon, 4 Mar 2002 14:57:09 -0800

> platform-specific directory? Are most MIPS-based Linux platforms not

General rant, not directed to you personally.  Right now we've got more
than half a dozen variations of code to support compressed images throughout
the kernel.  So I'm not going to accept any new patches for compressed
images before this mess has been cleaned.  Volunteers :-)

  Ralf

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From: Jun Sun <[email-masked]>
Date: Mon, 04 Mar 2002 14:50:43 -0800

> images before this mess has been cleaned.  Volunteers :-)

I think I am leaning towards leaving compressed image outside kernel itself.

I don't see any technical reason why it must be inside kernel.

Then it must be the code sharing argument.  However, it seem MIPS boards are 
so much more diversified than x86 machines.  Any sharing, if there are any, is 
limited.  Also there are other way of sharing code than stacking it into 
kernle tree, I suppose.

Another aimless general rant .... :-)

Jun

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From: William Jhun <[email-masked]>
Date: Mon, 4 Mar 2002 15:03:34 -0800

> Another aimless general rant .... :-)

But this is a good point. Our own compressed/ build requires building
several elf-header-mangling tools just to get our bootstrap (which we
can't change) to even recognize the finished image.

Though, I'm not sure how much the different decompression (misc.c)
routines vary; could there be some way to do this in a
platform-independent way?

Hmm!
Will

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From: Geoffrey Espin <[email-masked]>
Date: Mon, 4 Mar 2002 15:19:31 -0800

On Mon, Mar 04, 2002 at 02:57:09PM -0800, Ralf Baechle wrote:
>                                                Right now we've got more

Do you mean just the 'ad hoc' MIPS schemes, or across the whole gamut of
Linux architectures?

The problem isn't so much the compression mechanics, but the BSP/LSP.

It would be helpful if there was one architecture that was
considered the 'ideal'.  Though I haven't actually used it:
arch/ppc/boot appears very flexible, and adheres to a strict
layout and naming convention.

Geoff
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From: Geoffrey Espin <[email-masked]>
Date: Mon, 4 Mar 2002 15:35:42 -0800

> platform-independent way?

Pete Popov's mips/zboot is probably the most generic for MIPS,
though, it only was done for Alchemy's.  See:

    http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/linux-mips/linux/arch/mips/zboot/

[I re-ported it to Korva and reduced much of the extraneous fluff
(both extra misc- source files and unneeded utils/), but its
never been checked into CVS.]

Geoff
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