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    SubjectRe: Being more anal about iospace accesses..
    Jörn Engel wrote:
    > On Wed, 15 September 2004 09:30:42 -0700, Linus Torvalds wrote:
    >
    >>For example, if you don't know (or, more importantly - don't care) what
    >>kind of IO interface you use, you can now do something like
    >>
    >> void __iomem * map = pci_iomap(dev, bar, maxbytes);
    >> ...
    >> status = ioread32(map + DRIVER_STATUS_OFFSET);
    >
    >
    > C now supports pointer arithmetic with void*? I hope the width of a
    > void is not architecture dependent, that would introduce more subtle
    > bugs.
    >
    > Jörn
    >

    http://gcc.gnu.org/onlinedocs/gcc-3.4.2/gcc/Pointer-Arith.html#Pointer-Arith

    5.18 Arithmetic on void- and Function-Pointers

    In GNU C, addition and subtraction operations are supported on pointers
    to void and on pointers to functions. This is done by treating the size
    of a void or of a function as 1.

    A consequence of this is that sizeof is also allowed on void and on
    function types, and returns 1.

    The option -Wpointer-arith requests a warning if these extensions are used.

    --
    Brian Gerst
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