Bootable CD BSD system?

[Tim Kientzle]

MacMan20001 wrote:
> Hello.
> 
> I'm trying to make a BSD system from a bootable CD. I don't need 
> anything fancy, just a shell and a few basic commands. I have the 
> structure of the CD in line. My problem is with the boot image.
> 
> I've read the FAQ on bootable CDs with mkisofs, and I did what it said: 
> use the format
> 
> mkisofs -U -R -b /boot/image/here -o /cd/image/here /tree/to/copy
> 
> I set the boot image to /boot/cdboo, making a guess. It said something 
> like "boot image size not allowed." Then, I remembered the manual page 
> where it said "boot images must be the size of a 1200, 1440, or 2800 KB 
> floppy". Unfortunately, none of the files in /boot were that size.
> 
> So, I tried a generic boot image with this command.
> 
> mkisofs -U -R -G /boot/cdboot -o /home/image.iso /home/discfolder
> 
> It accepted it, and made image.iso without error. I burned it onto the 
> CD, rebooted, and it went straight for the hard disk.
> 
> I double checked my BIOS. I had put CD above the hard disk before when I 
> installed, and sure enough, it never changed. I popped the install CD in 
> and rebooted, and it accepted that as the boot disk.
> 
> Do I have the wrong idea about what a boot image is? or did I miss 
> something? I am new at this...
> 
> Any help would be nice.

The old "El Torito" CD booting loaded a floppy disk image and then
booted that.  With this scheme, you first create a bootable floppy, then
place an image of that floppy in a file and use -b with that file.
This is ugly.

You would rather use -b  with --no-emul-boot.  The --no-emul-boot
flags the boot image as a raw executable rather than a floppy image.
The /boot/cdboot loader is specifically designed for this use.

Good luck,

Tim