Re: FatELF patches...

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

Lets go down the list of "benefits"

- Separate downloads
	- Doesn't work. The network usage would increase dramatically
	  pulling all sorts of unneeded crap.
	- Already solved by having a packaging system (in fact FatELF is
	  basically obsoleted by packaging tools)

- Separate lib, lib32, lib64
	- So you have one file with 3 files in it rather than three files
	  with one file in them. Directories were invented for a reason
	- Makes updates bigger
	- Stops users only having 32bit libs for some packages

- Third party packagers no longer have to publish multiple rpm/deb etc
	- By vastly increasing download size
	- By making updates vastly bigger
	- Assumes data files are not dependant on binary (often not true)
	- And is irrelevant really because 90% or more of the cost is
	  testing

- You no longer need to use shell scripts and flakey logic to pick the
  right binary ...
	- Since the 1990s we've used package managers to do that instead.
	  I just type "yum install bzflag", the rest is done for me.

- The ELF OSABI for your system changes someday?
	- We already handle that

- Ship a single shared library that provides bindings for a scripting
  language and not have to worry about whether the scripting language
  itself is built for the same architecture as your bindings. 
	- Except if they don't overlap it won't run

- Ship web browser plugins that work out of the box with multiple
  platforms.
	- yum install just works, and there is a search path in firefox
	  etc

- Ship kernel drivers for multiple processors in one file.
	- Not useful see separate downloads

- Transition to a new architecture in incremental steps. 
	- IFF the CPU supports both old and new
	- and we can already do that

- Support 64-bit and 32-bit compatibility binaries in one file. 
	- Not useful as we've already seen

- No more ia32 compatibility libraries! Even if your distro
  doesn't make a complete set of FatELF binaries available, they can
  still provide it for the handful of packages you need for 99% of 32-bit
  apps you want to run on a 64-bit system. 

	- Argument against FatELF - why waste the disk space if its rare ?

- Have a CPU that can handle different byte orders? Ship one binary that
  satisfies all configurations!

	- Variant of the distribution "advantage" - same problem - its
	  better to have two files, its all about testing anyway

- Ship one file that works across Linux and FreeBSD (without a platform
  compatibility layer on either of them). 

	- Ditto

- One hard drive partition can be booted on different machines with
  different CPU architectures, for development and experimentation. Same
  root file system, different kernel and CPU architecture. 

	- Now we are getting desperate.

- Prepare your app on a USB stick for sneakernet, know it'll work on
  whatever Linux box you are likely to plug it into.

	- No I don't because of the dependancies, architecture ordering
	  of data files, lack of testing on each platform and the fact
	  architecture isn't sufficient to define a platform

- Prepare your app on a network share, know it will work with all
  the workstations on your LAN. 

	- Variant of the distribution idea, again better to have multiple
	  files for updating and management, need to deal with
	  dependancies etc. Waste of storage space.
	- We have search paths, multiple mount points etc.

So why exactly do we want FatELF. It was obsoleted in the early 1990s
when architecture handling was introduced into package managers.