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    SubjectRe: Unable to boot a raw kernel image :??
    DervishD wrote:
    >
    > Hi all :))
    >
    > A time ago I was able to generate bootable Linux CD's just by
    > dd'ing a floppy containing a raw kernel image:
    >
    > dd if=/dev/fd0 of=eltorito
    >
    > After that, mkisofsing, toasting and booting. But now, depending
    > on the machine, I have 'invalid compressed format' errors, or even
    > ye olde register dump when the image was damaged :(
    >
    > Booting directly from the floppy works, but booting with that
    > same image from a CD does not :(( I now I can use LILO, or better
    > yet, Syslinux or isolinux, but I'm just curious why I cannot boot raw
    > image-based CD's anymore.
    >
    > Anyone knows what's happenning here?

    I had this problem a while ago. It turned out to be a (widespread)
    BIOS bug triggered be the disk-size probe of the kernel's boot loader.

    The crude fix which worked for me: disable the probing for 2.88MB disks
    by changing the first byte of the disksizes table at the end of bootsect.S
    from 36 to 18.

    The long explanation: The BIOS allows bigger-than-track-size reads
    in El-Torito mode which confuses the probe routine which then assumes
    a 2.88MB disk when the BIOS is actually emulating a 1.44MB disk.
    In LBA mode that would be no problem but in CHS mode (which is used
    by the loader) it does not work.

    Ciao, ET.
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