Subject: Re: Create bootable kernel-only ISOs in addition to *.fs floppy
To: None <firstname.lastname@example.org>
From: Havard Eidnes <he@NetBSD.org>
Date: 05/11/2006 14:55:40
I see there's not been many responses to this one, and I think this
should be discussed.
I suspect one reason you didn't get many responses is that it required
active chasing of referenced material to beging to understand what it
is that you actually propose.
I've chased the references, and I still have problems understanding
how you intend to circumvent the 2.88MB size limitation for floppy
emulated El Torito boot CD images. Maybe that's just me, so please
bear with me...
What we have today, in terms of code to create ISO images for use on
i386 and amd64, is, as I understand it:
1) Code in etc/Makefile, etc.$MACHINE/Makefile.inc, and in build.sh's
"iso-image" action which will produce a single-architecture
installation CD iso image after $RELEASEDIR has been otherwise
fully populated. This relies on a kernel with a ramdisk plugged in
("kernel+ramdisk"), compressed, fitting inside a 2.88MB floppy
image together with the boot loader, and that resulting image is
used as the El Torito boot image.
2) Code in distrib/cdrom/ which is a complicated setup (I've never
tried to use it myself...) to create bootable multi-architecture
iso images, i.e. the same CD can can be booted on several different
architectures through some clever mix and match of different boot
methods. The contents is still that of an "install image", i.e.
the full installation sets for each architecture are also to be
found inside the ISO image. (The i386/amd64 boot method is still
the El Torito via a "big" kernel+ramdisk+bootloader floppy image.)
I do understand that your proposal is not to create "install images",
i.e. the install sets will not be part of the "boot cd" images.
Will the new "boot cd" images be constructed using our own makefs
using the relatively new "-t cd9660" option?
Which boot method will your boot images use (for i386 and amd64)? El
Torito? HD emulation? If it's El Torito, how do you get around the
2.88MB limitation? In some places you talk of "kernel+ramdisk", which
is essentially what we have today, and this is confusing me as to how
you intend to get rid of this problem. Could you please spell out the
juicy bits on this point?
Lastly I'd suggest that unifying build.sh's / etc/Makefile's iso-image
on the one hand and distrib/cdrom/'s ISO image construction method
should probably be a separate matter. Both of these serve their own
purpose and have their own preconditions for use, and I think I'd
dislike to have one of them disappear, especially if there is nothing
else in this particular proposal which necessitates a complete
overhaul of either of them (and I don't think that's the case).