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    SubjectRe: [PATCH] Use correct x86 reboot vector
    Andi Kleen wrote:
    > Extensive discussion by various experts on the discuss@x86-64.org
    > mailing list concluded that the correct vector to restart an 286+
    > CPU is f000:fff0, not ffff:0000. Both seem to work on current systems,
    > but the first is correct.

    You are right. That's what a 286 does when the RESET signal is asserted.

    Which is amazing, because I wrote that ffff:0000 and I was reading
    from the Phoenix BIOS book at the time. It was long ago but I'm
    fairly sure I got that address from the book.

    I just did some Googling and found that there examples of DOS code
    fragments using both vectors. Also, the original IBM BIOS (as they
    say) had a long jump at the vector, which is presumably one of the
    many de facto ABIs which real mode programmers grew to depend on.

    > See the "DPMI on AMD64" and "Warm reboot for x86-64 linux" threads
    > on http://www.x86-64.org/mailing_lists/list?listname=discuss&listnum=0
    > for more details.

    One would hope that AMD64 systems, being a new design and all, offer a
    documented and reliable method of rebooting.

    It should never be necessary to have to write "reboot=..." on the
    kernel command line to choose which legacy method works on different
    AMD64 motherboards. Am I too idealistic?

    -- Jamie
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