I got dsl (dammsmalllinux) from a page in australia with a taiwanese url and german advertisments and compared extraction with a loop (superuser mode) and win 7z and there was a huge difference in where the files went.
If 7z is moving stuff or unable to track the paths sometimes, this could explain the apparent dirth of usable docs on how to make a customized bootable repair CD. Some docs leave out this detail, some leave out that. Nowhere do we see a concise description of files that are needed, where they go and what they consist of… and how to make them (all).
boot.cat is missing from some.
How to and what parts have to be prepared as iso (sub systems) is also missing. How to create, how large, and what the boot.cat file is is also missing from some.
The best starter kit is from UBCD51, but it creates the thing using freedos and not only that… it was wrong about 7z being able to read and create ‘cab’ files. It reads 'em ok, but when we get to the custom menu, enter dos and find where it stuck our new cab file, it won’t open.
So for the moment I’m stuck, but I thought I’d jump on a soapbox and ask the (by now obvious) question. is 7z responsible for the lack of decent boot cd documentation? Is it screwing up iso extraction so that rewriting the cds can’t work?
Is creating bootables is now a nearly lost art? Or something best left to the vendor-friendly operating system?
Obviously every Linux distro knows how to master CDs, using only Linux tools. I believe Debian has a remastersys tool that you could study for techniques.
The only difference between the version I extracted using mount and copying the files (requires a loop), is now the [BOOT] directory created by 7z.
It contains one file named BootableNoEmulation.img, which is just a copy of the first 2048 bytes of /boot/isolinux/isolinux.bin and only means that it’s a normal iso (not a usb boot image or anything).
Starting to get interesting.
Anyway… now I’m looking at the KNOPPIX file which appears to be a small script appended to a binary image of some sort. The script mounts itself, and is followed by about 48 megs of binary data. Possibly compressed.
As far as the Remaster tools go, I’ll probably check that out too. But I wonder why it didn’t show in the first hundred or so items that showed in a search of the web.
Bottom line is, you’re right, of course. But somehow it turns out that very few people actually know how to do it, apparently.
I should add that my goal is not to remaster KNOPPIX, but to understand and remaster the opensuse 11.4 rescue system.
I can reinstall the default kde setup in 12 minutes with a tarball that fits nicely on a DVD. I just need the tools to mount and do the work, possibly avoiding destruction of the home folder.
The opensuse stuff is just too complicated to understand, so the simpler examples in UBCD and dam*smalllinux are much better for me.
Once I know how the parts interact I can come back to the opensuse distro and extract/modify the parts I need.
Very few people have to know this but the knowledge is openly available. Making a bootable CD image is the easy bit. If you just need to load a kernel you’re done. Perhaps load the initrd if you are running from RAM. But if you need to run an installer or rescue system then things get more intricate. But there is no shortage of mastering tools.
On 2011-11-30 05:26, rainbowsally wrote:
> Bottom line is, you’re right, of course. But somehow it turns out that
> very few people actually know how to do it, apparently.
Because few people need to do it.
I’m guessing the part you miss is that the bootable part is not in the iso
image, but in the “eltorito” part.
I am aware of the el torito thing as it applies to 2.88 meg floppies and I understand that it also applies to cd roms somehow. I’ll check that out too, but the knoppix lead wasn’t much help as it turns out.
On 2011-12-02 10:26, rainbowsally wrote:
> I am aware of the el torito thing as it applies to 2.88 meg floppies
> and I understand that it also applies to cd roms somehow. I’ll check
> that out too, but the knoppix lead wasn’t much help as it turns out.
It is the bootable part of any bootable CD or DVD. It emulates a floppy.
The floppy boots the machine, then it reads the ISO.
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Cheers / Saludos,
Carlos E. R.
(from 11.4 x86_64 “Celadon” at Telcontar)