linux-kernel - Re: FatELF patches...

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Date:	Tue, 3 Nov 2009 02:35:55 +0100
From:	Mikael Pettersson <mikpe@...uu.se>
To:	david@...g.hm
Cc:	Krzysztof Halasa <khc@...waw.pl>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	"Ryan C. Gordon" <icculus@...ulus.org>,
	Måns Rullgård <mans@...sr.com>,
	linux-kernel@...r.kernel.org
Subject: Re: FatELF patches...

david@...g.hm writes:
 > > FatELF means you have to compile for many archs. Do you even have the
 > > necessary compilers? Extra time and disk space used for what, to solve
 > > a non-problem?
 > 
 > you don't have to compile multiple arches anymore than you have to provide 
 > any other support for that arch. FatELF is a way to bundle the binaries 
 > that you were already creating, not something to force you to support an 
 > arch you otherwise wouldn't (although if it did make it easy enough for 
 > you to do so that you started to support additional arches, that would be 
 > a good thing)

'bundle' by gluing .o files together rather than using what we already have:
directories, search paths, $VARIABLES in search paths, and ELF interpreters
and .so loaders that know to look in $ARCH subdirectories first (I used that
feature to perform an incremental upgrade from OABI to EABI on my ARM/Linux
systems last winter).

Someone, somewhere, has to inspect $ARCH and make a decision. Moving that
decision from user-space to kernel-space for ELF file loading is neither
necessary nor sufficient. Consider .a and .h files for instance.

 > > I'm surprised this idea made it here. It certainly has merit for
 > > installation medium, but it's called directory tree and/or .tar or .zip
 > > there.
 > 
 > if you have a 1M binary with 500M data, repeated for 5 arches it is not a 
 > win vs a single 505M FatELF package in all cases.

If I have a 1M binary with 500M non-arch data I'll split the package because
I'm not a complete moron.

IMNSHO FatELF is a technology pretending to be a solution to "problems"
that don't exist or have user-space solutions. Either way, it doesn't
belong in the Linux kernel.
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