Comment by schoen | Hacker News Reader

Comment by schoen | Hacker News Reader

I was the lead developer of the Linuxcare business card and the later LNX-BBC, and I also want to mention that Knoppix is a huge name in Linux live CD history.

Knoppix (developed by Klaus Knopper) ended up using the cloop driver, which Rusty Russell originally wrote for LNX-BBC. It added transparent gzip compression to the loopback filesystem mount concept and I think it allowed us to ship about twice as much software on a 50 megabyte CD-ROM! (And similarly, Knoppix could then ship about twice as much software on a full-size CD-ROM.)

In general, doing better than raw ISO9660 for read-only file storage was an important challenge for would-be tiny live and embedded Linux systems. I think there are several things that have followed cloop, directly or indirectly inspired by it.

I think you could still do quite a lot with a live USB system today. At Linuxcare we heard from a lot of IT desktop support people who were regularly using the bootable business card to fix/back up Linux and Windows systems, or sometimes for forensics, lost password resets, or other creative applications.

Edit: Knoppix existed slightly earlier than the Linuxcare project, even though it adopted that one particular cloop technology from us. I think it was probably an inspiration for the Linuxcare group. I don't know my Knoppix history very well, but I think I saw some form of Knoppix as early as 1997!

Edit 2: According to Wikipedia my recollection may be wrong because the first known official Knoppix release is 2000 (though that's version 1.3, so maybe there was a 1.0 sometime before that?) See https://en.wikipedia.org/wiki/Knoppix and https://en.wikipedia.org/wiki/Klaus_Knopper (amazing to see that Knoppix is still being actively developed to this day!).

Edit 3: Thanks to someone elsewhere in this thread for mentioning tomsrtbt by Tom Oehser (http://www.toms.net/rb/), which was also definitely an inspiration for the Linuxcare distribution. It had the motto "the most Linux on 1 floppy disk", later modified to "the most GNU/Linux on 1 floppy disk". While it didn't have a GUI, like the QNX floppy, you could do quite a bit with it!

Do you happen to know what the early bootloading situation was?

I'm familiar with ISOLINUX[1] (a very small bootloader for iso9660 cd roms) and SYSLINUX (for bootloading floppies (from which isolinux is derived, i believe?)). Was this a key enabling technology? Were other bootloading solutions ever used?

[1] https://wiki.syslinux.org/wiki/index.php?title=ISOLINUX

The Linuxcare bootable business card always used ISOLINUX and it was very pleasant (as it could read ISO9660 filesystems to find various objects on them, such as kernel and root filesystem images). I'm not positive what other systems used.

I think LILO was less widely used on live CDs because BIOSes had trouble letting it access CD-ROMs. My recollection of the details of the exact problems with this has grown a little hazy, though.

I think more modern systems are able to use GRUB in a relatively media-independent way, but I haven't followed this area enough to understand how GRUB is able to be so media-independent.

CD-ROMs and some other boot media use something called the El Torito standard (https://wiki.osdev.org/El-Torito), which is so named because a bunch of computer industry people -- I think in 1993 or 1994 or something? -- got together at a restaurant called El Torito to hash out the details. This describes how the BIOS can find the OS boot loader within the ISO9660 filesystem on the optical media. The tools for making an ISO9660 image had an option where you could indicate which file should be the El Torito special next-stage image, so I think we were supposed to indicate the ISOLINUX output this way, and it would get the right location (and maybe other metadata) so that the BIOS would be happy to boot it.

El Torito support in BIOSes was surprisingly universal considering how relatively unofficial a standard it was. In particular, ISO9660 was published by the ISO as a work product of a formal committee, while the El Torito extension was, I think, just some people who met at a restaurant this one time!

Edit: 1994 in Irvine, CA, apparently, according to https://en.wikipedia.org/wiki/ISO_9660#El_Torito; if the coordinates in the article are to be believed, the restaurant is still there, at Main and Mercantile, literally right across the street from SNA airport. Which might, in turn, be the reason they picked that restaurant?

On the topic of cloop, any idea why it never made it to mainline? Its hugely useful in itself, and I use it for some custom boot images built with buildroot, but it breaks on nearly every kernel upgrade. Also finding the latest cloop source always feels like a treasurehunt.

Everytime I ask about cloop in mainline, I get told to switch to squashfs - which is fine, just that cloop has uses well outside squashfs' domain.

I guess one answer is just that we never tried, and the kernel was stable enough during the time that we were releasing our distribution that I think we only needed a total of one patch from Rusty and/or from Klaus Knopper. Presumably it would (just) have needed someone to be willing to maintain it in the kernel at the time.

One element of this is that cloop was, quite literally, a quick hack (I think Rusty wrote the original version in a single day), which then worked incredibly well for our use case.

Sorry about that.

Trinux was another early floppy-based Linux bootable distribution. It's claim to fame over the better-known (and more self-contained) tomsrtbt was that it could read from successive floppies (typically 2-3 discs) to make a wider range of tools (mostly security / network forensics) available.

The old dev site is still up on Sourceforge:

http://trinux.sourceforge.net/legacy/

I came here just to say how in Germany knoppix was huge (and for most people the first exposure to Linux). In addition to most Linux users I know many advanced Windows users who always had a a knoppix CD laying around to fix broken PCs.

I still have my Linuxcare BBC. And tomsrtbt and QNX media. Fun times.

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