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    SubjectRe: Being more anal about iospace accesses..
    On Wed, Sep 15, 2004 at 10:07:29AM -0700, Linus Torvalds wrote:

    > C doesn't. gcc does. It's a documented extension, and it acts like
    > if it was done on a byte.

    [...]

    > It's a singularly good feature.

    I dunno about that. Maybe it is, but it has some gotchas.

    Recently when doing a sparsification of code I noticed there are
    places which essentially do things like:

    void *foo;

    [...]

    foo += bar * n;

    Part of the fix (cleanup) was to change the 'void *foo' to
    'gratuitous_typedef_t __user *foo' --- which silently breaks the math
    if you don't explicitly check for this.


    --cw
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