On Thu, 30 Oct 2014, Ley Foon Tan wrote: > On Tue, Oct 28, 2014 at 9:38 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > > On Friday 24 October 2014 16:24:31 Ley Foon Tan wrote: > >> +DECLARE_EXPORT(__gcc_bcmp); > >> +DECLARE_EXPORT(__divdi3); > >> +DECLARE_EXPORT(__divsi3); > >> +DECLARE_EXPORT(__moddi3); > >> +DECLARE_EXPORT(__modsi3); > >> +DECLARE_EXPORT(__udivdi3); > >> +DECLARE_EXPORT(__udivmoddi4); > >> +DECLARE_EXPORT(__udivsi3); > >> +DECLARE_EXPORT(__umoddi3); > >> +DECLARE_EXPORT(__umodsi3); > >> +DECLARE_EXPORT(__muldi3); > >> > > > > I don't remember what all of these are, but at least some of them seem > > to be concerned with 64-bit division. By convention, we don't provide those > > in the Linux kernel but instead require all code to use the do_div() > > macro instead. > Do you mean kernel doesn't support 64 bit division result for a 32-bit > architecture? Because do_div() only support 32-bit division result for > 32-bit architecture. > Compiler will auto generate call to __divdi3() for the following > example code. This means loadable module will have compilation error > if we don't export symbol for __divdi3, but built-in module is fine. > Is this an expectation? Or we can keep 64-bit division symbols here > since they are no harm (they are software emulation when without > hardware divider). > > long long a, b, c; > a = b / c; We have proper helper functions for this: See include/linux/math.h Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
