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    SubjectRe: Being more anal about iospace accesses..
    On Wed, 15 September 2004 10:07:29 -0700, Linus Torvalds wrote:
    > On Wed, 15 Sep 2004, Jörn Engel wrote:
    > >
    > > C now supports pointer arithmetic with void*?
    >
    > C doesn't. gcc does. It's a documented extension, and it acts like if it
    > was done on a byte.
    >
    > See gcc's user guide "Extension to the C Language Family".
    >
    > It's a singularly good feature.

    Nice.

    But it still leaves me confused. Before I had this code:

    struct regs {
    uint32_t status;
    ...
    }

    ...

    struct regs *regs = ioremap(...);
    uint32_t status = regs->status;
    ...

    So now I should do it like this:

    #define REG_STATUS 0

    ...

    void __iomem *regs = ioremap(...);
    uint32_t status = readl(regs + REG_STATUS);
    ...

    But wait, that only works when long is 32bit wide. Plus I could be
    stupid enough and "#define REG_STATUS 64" while the register space is
    just 64 bytes long. It solves the confusion about address spaces,
    agreed, but overall I'm more confused now. Hope it's just temporary.

    Jörn

    --
    There is no worse hell than that provided by the regrets
    for wasted opportunities.
    -- Andre-Louis Moreau in Scarabouche
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