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From:   Jeffrey Walton <noloader@gmail.com>
Date:   Wed, 24 Jan 2018 11:38:42 -0500
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Subject: Re: [PATCH RFC 0/3] API for 128-bit IO access
To:     Yury Norov <ynorov@caviumnetworks.com>
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On Wed, Jan 24, 2018 at 4:05 AM, Yury Norov <ynorov@caviumnetworks.com> wrote:
>
> ...
> With all that, this example code:
>
> static int __init 128bit_test(void)
> {
>         __uint128_t v;
>         __uint128_t addr;
>         __uint128_t val = (__uint128_t) 0x1234567890abc;
> ...

In case it matters, you can check for GCC support of the 128-bit types
in userland with:

#if (__SIZEOF_INT128__ >= 16)
   ...
#endif

Also see https://gcc.gnu.org/ml/gcc-help/2015-08/msg00185.html .

Jeff