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    SubjectRe: RFD: x32 ABI system call numbers
    On 08/31/2011 08:09 PM, H. Peter Anvin wrote:
    > > I really think that "x32" should try to aim *VERY* hard at using the
    > > 64-bit system calls, and seeing itself as being a "32-bit application
    > > in a 64-bit world". That's not just true for time_t (which I think
    > > should be 64-bit on anything new that expects to survive for any
    > > amount of time), but in general.
    > We're trying for it. The things we're trying to avoid is to muck (too
    > much) with the compat layer for the mega-multiplex system calls like
    > ioctl. We can't just use the 64-bit ioctl because ioctl structures
    > generally contain pointers.

    struct iovec
    void __user *iov_base; /* BSD uses caddr_t (1003.1g requires
    void *) */
    __kernel_size_t iov_len; /* Must be size_t (1003.1g) */
    } __attribute__((x32_abi_64));

    typedef long time_t __attribute__((x32_abi_64));

    The x32_abi_64 attribute converts pointers and longs back to 64-bit and
    adjusts the alignment accordingly. If we tag all userspace visible
    structures with this attribute, we can use the 64-bit ABI without changes.

    &my_iovec->iov_base yields something that is not a void ** (reads of a
    64-bit pointer decay to a 32-bit pointer, writes zero extend).
    printf formats will break
    if someone embeds an iovec in a structure, it will occupy more space
    than expected

    error compiling committee.c: too many arguments to function

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      Last update: 2011-09-01 15:33    [W:0.026 / U:17.232 seconds]
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