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    SubjectRe: [PATCH] x86 Boot enhancements, boot protocol 2.04 7/9
    "H. Peter Anvin" <> writes:

    > Agreed. Note that so far putting the real mode code *above* 0x90000 is
    > completely untested. It *should* work with boot protocol 2.02 support; it
    > almost certainly *does not* work with earlier boot protocols (due to the "move
    > it back to 0x90000" braindamage.)

    Having misc.c move the real mode code and the command line above
    0x90000 avoids this issue. I relocate the command line so
    cmd_line_ptr must be written. This looses track of exactly which
    protocol version the bootloader was using, but it doesn't matter as
    all the kernel cares about is being able to find it's command line,
    and the command line can still be found. For code coming in the new
    32bit entry point we are above protocol version 2.02 when the problem
    was fixed.

    I have now solved the space/reliability tradeoff with belt and suspenders.

    I have modified misc.c to do an inplace decompression. This means I
    use approximately 78KB of memory below 1MB and 8 bytes more than the
    decompressesed kernel above 1MB. And if I have to except for the 5KB
    of real mode code I can put everything above 1MB. The 78KB is 5KB
    real mode code 10KB decompressor code 61KB bss.

    The change is especially nice because now in my worst case of only
    using 5KB real mode data, I do better than the best case with previous
    kernels (assuming it isn't a zImage). And if I ever get the bootmem
    bootmap fixed I can put initrds down at 2.6MB and not have to worry
    about them getting stomped :)


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