Re: Question about building a full bootable image using (Debian 7)
On Sat, Sep 28, 2019 at 01:21:19PM +0000, g4jht wrote:
> Hi, I am sending this to you guys in a sort of last resort desperation.
> As it only relates to Debian as that is my current build environment.
>
> Help Please.
>
> My problem how to build a bootable iso image file (not of Debian)
>
> I have an iso file [for an early version of UNIX (x86_32 code)]. I have
> stripped the files into a directory, then copied them (via tar) into my iso
> build directory, made my modifications I am OK up to that point.
Copying the files from a CD does not include copying any boot code from
the CD. Assuming it ever was bootable.
> My Question is:
> How do I create a new bootable iso image file from my build directory ready
> for burning onto a DVD.
> I tried just burning the build directory tree but did not boot (I suspected
> as much but did it anyway).
> I am obviously missing as step maybe tools. target is a 486 bare machine and
> a P6 machine in both cases without an O/S, what on the DVD will eventually
> end up on the HD, once the DVD "works".
> Any help appreciated, and I know this sort of an oddball question.
>
> [please CC me directly with your solution, thank you.
>
> regards, Dave :-) (Ps not a newbie).
How you make a bootable CD depends on the boot system supported
by the target system, and which boot loader you have. On x86
machines, the boot system for CD has usually been 'el torito'
https://en.wikipedia.org/wiki/El_Torito_(CD-ROM_standard)
Certainly the mkisofs/xorriso/etc tools have options to tell it where
the boot loader floppy image or HD style boot files are. Booting from
HD/USB is totally different, so making it boot from CD/DVD has nothing
to do with booting from HD. Very few 486 machines can even boot from
CD at all in my experience. It just wasn't a thing yet. I remember
having to make boot floppies to install Windows NT4 on a Pentium Pro
in 1997, because the Adapter 2940UW firmware didn't support 'el torito
no emulation' boot yet, which NT used, while linux installs could boot
because they used 'el torito floppy emulation' boot mode instead. At a
later time a firmware update for the scsi controller added the needed
support to allow directly booting NT and newer linux installers that
used the other mode.
--
Len Sorensen
Reply to: