Subject: Re: Switching i386/amd64 to native CD-based installation?
To: Martin Husemann <>
From: John Clark <>
List: tech-install
Date: 06/28/2005 10:14:54
Martin Husemann wrote:

>On Tue, Jun 28, 2005 at 10:36:32AM +0200, Robert Cates wrote:
>>I use the 2.88MB boot big-image to create bootable DVDs.  So I hope you 
>>keep up with them, or provide/suggest a replacement that I can use.
>The whole thread is about utilizing the new non-emulation boot cd stuff.
>With cdboot instead of biosboot you won't need any 2.88MB floppy image - 
>you can boot arbitrary kernels straight from CD.

Most of my activities are in the embedded environment, and with the 
proliferation of Compact Flash,
and USB 'bootable' devices, I've not worried about floppies much at all, 
and in fact, not worried
about 'cd boot' either.

However, what is the BIOS support for a 'native' boot off of CD's. I 
thought the El Torrito method
was the only supported method, and while one could modify that process 
significantly, say have
a pretty much empty dummy floppy, one still had to use that convention 
to support CD booting
cross 'all(most/significan numbers)' of x86 platforms.

Has something been added to the BIOS which allows for CD directory 
lookups (is that catalog,
it's been so long since I even worried about CDs at all...). As I recall 
the El Torrito method
had a list in a specific offset from the first sector(however defined) 
and consisted of a list of
offsets to further regions of the disk.

As I recall when I did my own home brewed booting for M68K/PPC systems 
off of CD's one
had to create a CD image, then 'fix up' the region inquestion, then 
write the mess to the CD
using a linux based burner. As I recall I did break the 'sematics' of 
the EL Torrito, as in the
thing pointed to was really a kernel, which loaded into memory then 
copied itself
around after that. I.e. I didn't create a 'real' floppy, just used the 
area on the CD allocated
to 'El Torrito' use.

This is all ancient history for me, and so, I could be misrecollecting 
some portions of the

John Clark