Reaching the 512 MiB installation limit
=======================================

A way to save some space would be to remove all files in inst-sys that are
already part of the initrd.

ATM both initrd and inst-sys are self-contained; that is, all lib
dependencies are resolved. This leads to some duplicates: e.g. glibc is both
in initrd and inst-sys.

We can remove the duplicate files from inst-sys and save quite some space.
But this will mean that only the inst-sys that was created together with the
initrd can be used. linuxrc can enforce this (the check exists but is
disabled by default).

I've done some test builds and here are the numbers:

- total image size (initrd + instsys) in MiB
			before		after		saved
factory i586		224.5		194.1		30.4
factory x64_64		215.6		185.6		30.0
sle12-sp2 aarch64	162.6		147.0		15.6
sle12-sp2 ppc64le	162.6		145.2		17.4
sle12-sp2 s390x		147.0		129.2		17.8
sle12-sp2 x86_64	176.1		158.4		17.7
sle12-ga aarch64	119.8
sle12-ga ppc64le	138.8
sle12-ga s390x		122.1
sle12-ga x86_64		151.0

As you can see, quite some part of the 512 MiB are already taken by file
system images - and it's growing.

If things get worse, a major blob to get rid of (except on s390x) would be
the kernel modules (after udev has loaded everything that's needed). With
the added pitfall that things like raid or lvm that are loaded later must be
exempt from this.

- kernel modules (compressed) in MiB
factory i586		49.1
factory x86_64		50.0
sle12-sp2 aarch64	26.9
sle12-sp2 ppc64le	16.8
sle12-sp2 s390x		 5.9
sle12-sp2 x86_64	28.8