The old setup worked fine with an ext2 initrd but fails with an initramfs,
either because autodetection is different for initramfs or because of kernel
changes (I suspect the first).
This means that booting s390 from CD has not worked since sometime during the
Etch release cycle, even though support for booting from CD was only added
early in that cycle - ouch.
For booting with an initramfs initrd we apparently need to specify its
offset and size at specific memory locations.
Change is based on SuSE's CD boot. Many thanks to Adam Thornton, Mark Post
(of Novell) and Bastian Blank for providing the pointers to the missing bits.
This fixes booting from CD using the d390.ins file; tested in Hercules for
both Lenny (31-bit kernel) and Squeeze (64-bit kernel).
Booting from CD using the d390.tdf file may still be broken (if possible at
all) as I have no idea how to test that.
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