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    SubjectRe: x86 setup code rewrite in C - revised
    On 07/13/2007 10:25 AM, Etienne Lorrain wrote:

    [ Added back cc:'s]

    > On Thu, 12 Jul 2007, Linus Torvalds wrote:
    >> On Thu, 12 Jul 2007, Andrew Morton wrote:
    >>> This code has been in -mm since 11 May, as git-newsetup.patch. It has
    >>> caused (for what it is) astonishingly few problems. Maybe a couple of
    >>> build glitches and one runtime failure, all quickly fixed.
    >>>
    >>> I'd say it's ready.
    >> Ok. That makes it easy. I'll just merge it.
    >>
    >> Linus
    >
    > Have fun, this code:
    > - do not open the fast A20 gate before checking if the slow A20 gate is open or closed.
    > - uses in asm("") inputs which may or may not be set by the compiler in the stack,
    > after modifying the stack pointer in the asm block: at least has_eflag()
    > - The VGA recalc has the same bug as the assembly version where a VGA write protected
    > register is written (Overflow register) without setting the enable bit (see VGA docs).
    > - Does not save and restore %ds when printing a char on the screen (%ds is destroyed
    > only when the content of the screen scroll - only for some video cards)
    > - Has a "dn" for outl() which sliped in instead of "dN"
    > and probably few other problems - just seen those by reading the patches (the asm("")
    > are inlined in the C code - I find it more difficult to check).
    >
    > Also, I do not know if "m" is right in here:
    > static inline u8 rdfs8(addr_t addr)
    > {
    > u8 v;
    > asm("movb %%fs:%1,%0" : "=r" (v) : "m" (*(u8 *)addr));
    > return v;
    > }
    >
    > I may repeat me, but to find these kind of problems, it is very nice to have an ELF
    > file to do a readelf/objdump -D -m i8086 (even after final link).
    -
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