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    SubjectRe: [PATCH 12/12] i386 boot: Add an ELF header to bzImage
    Date
    "H. Peter Anvin" <hpa@zytor.com> writes:

    > Vivek Goyal wrote:
    >>>
    >> Hi Eric,
    >> I have added cld in the regenerated patch below.
    >
    > No, the cld needs to be earlier. It turns out this isn't the first use of
    > string instructions.

    Can we rely on the int calls not setting df? Otherwise we need to clear
    df at each use as we do with all of the later uses.

    > I think I am going to add DF=0 as a documented entry condition; it definitely
    > seems all current Linux kernels require it.
    >
    >> Also one more minor nit. stosb relies on being %es set properly. By the
    >> time control reaches loader_ok, i could not find %es being set explicitly
    >> hence I am assuming we are relying on bootloader to set it up for us. Maybe we
    >> can be little more paranoid and setup the %es before stosb. I
    >> have done this change too in the attached patch. Pleaese have a look.
    >> I know little about assembly code.
    >
    > %es being set is part of the requirements list, although it *would* be better to
    > not rely on any segment registers being set at all (only rely on %cs.)

    Agreed.

    Eric

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