Upx to compress bzimages?

[Petter Reinholdtsen <pere@hungry.com>]

I decided to check out Upx after finding the folling in
debian-isntaller/doc/README:

  Upx can compress bzimages. They're still bootable, and up to 100k
  might be saved this way. http://upx.sourceforge.net/

I checked, and the version in Sid (1.24) is only able to compress ELF
binaries.  When I tried it on the kernel, it printed this:

  # upx tmp/vmlinuz
                       Ultimate Packer for eXecutables
           Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002
  UPX 1.24         Markus F.X.J. Oberhumer & Laszlo Molnar         Nov 7th 2002

          File size         Ratio      Format      Name
     --------------------   ------   -----------   -----------
  upx: tmp/vmlinuz: UnknownExecutableFormatException

  Packed 0 files.
  #

I tried packing the programs in bin/ and usr/bin/, but this only made
the initrd.gz files larger.

Have anyone used upx successfully with d-i?