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    SubjectRe: Comments wanted: Linux/i386 boot protocol doc
    Alan Cox wrote:
    >
    > > | Reserved for BIOS | Do not use. Reserved for BIOS EBDA.
    > > 09A000 +------------------------+
    >
    > 9A000 is not a guaranteed address. The EBDA is defined by reading a low memory
    > value

    I know, and I address that in the document. Boot protocol 2.02 plus
    bzImage allows the boot loader the flexibility to set the memory ceiling
    quite low. However, we needed a "drop dead" address for existing
    kernels as well, and John, Hans and I came up with 0x9A000 as being
    something we can reasonably do. It is not always sufficient -- when
    using M-systems flash or PXE the EBDA is several hundred K in size.
    There is no way to support this with the old kernels which require
    mucking with the 0x90000 segment. Hence the revised protocol.

    However, I'll see if I can add a note.

    The problem is that most of these are hard limits for the boot loader --
    doing INT 12h to find out the ceiling only allows you to print an error
    message instead of crashing.

    -hpa

    --
    <hpa@transmeta.com> at work, <hpa@zytor.com> in private!
    "Unix gives you enough rope to shoot yourself in the foot."
    http://www.zytor.com/~hpa/puzzle.txt

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