On Wednesday, July 16, 2014 04:58:00 PM Lv Zheng wrote:
> This patch adds default 64-bit mathematics in aclinux.h using do_div(). As
> do_div() can be used for all Linux architectures, this can also be used as
> stub macros for ACPICA 64-bit mathematics.
>
> But this is not a performance friendly way, as ACPICA's architecture
> specific division OSL only requires a dividing 64-bit number with a 32-bit
> number implementation, while Linux __div64_32() is not available for all
> build environments. So currently, if an architecture really wants to
> support ACPICA, it must implement its own division OSL.
What does this mean for i386, in particular?
> This is required by the ACPICA header stub support. ACPICA header stubs are
> useful to protect CONFIG_ACPI=n Linux kernel builds where ACPICA headers
> are included. Lv Zheng.
>
> Signed-off-by: Lv Zheng <lv.zh...@intel.com>
> ---
> include/acpi/platform/aclinuxex.h | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/include/acpi/platform/aclinuxex.h
> b/include/acpi/platform/aclinuxex.h
> index 191e741..568d4b8 100644
> --- a/include/acpi/platform/aclinuxex.h
> +++ b/include/acpi/platform/aclinuxex.h
> @@ -46,6 +46,28 @@
>
> #ifdef __KERNEL__
>
> +#ifndef ACPI_USE_NATIVE_DIVIDE
> +
> +#ifndef ACPI_DIV_64_BY_32
> +#define ACPI_DIV_64_BY_32(n_hi, n_lo, d32, q32, r32) \
> + do { \
> + u64 (__n) = ((u64) n_hi) << 32 | (n_lo); \
> + (r32) = do_div ((__n), (d32)); \
> + (q32) = (u32) (__n); \
> + } while (0)
> +#endif
> +
> +#ifndef ACPI_SHIFT_RIGHT_64
> +#define ACPI_SHIFT_RIGHT_64(n_hi, n_lo) \
> + do { \
> + (n_lo) >>= 1; \
> + (n_lo) |= (((n_hi) & 1) << 31); \
> + (n_hi) >>= 1; \
> + } while (0)
> +#endif
> +
> +#endif
> +
> /*
> * Overrides for in-kernel ACPICA
> */
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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