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On Thu, 7 Dec 2006, Michael K. Edwards wrote: > Judging from the code in gcc/config/arm/arm.c (prefaced with "This has > now turned into a maze"), completely specifying the code generation > parameters involves: > -march > -mcpu (overrides -march, with a warning if they conflict) > -mtune (overrides tunings implied by -march and -mcpu, > but does not alter the __ARM_ARCH_xxx__ macro) > or if none of the above are specified, > interworking, thumb, and mode26/32 selectors, which can result in > selection of a different CPU tuning from the compile-time default; > followed by some more Thumb, PIC, and frame register related flags, and then: > -mabi > -mfpe > -mfpu > -mfloat-abi > -mtp > followed by structure alignment and the choice of PIC register. > Endianness seems to be handled elsewhere, and aliases like -macps and > -msoft-float appear to be mapped into the above. > > The OABI build of 2.6.19 that I just did has (among others): > -macps -mabi=apcs-gnu -march=armv5te -mtune=xscale > -Wa,-mcpu=xscale -msoft-float > It does not have FPE, FPU, and TP selectors. Does this mean that I > get the compiler's default float format (FPA vs. VFP)? Probably. But floating point in the kernel is forbiden anyway and the -msoft-float will ensure that no FP instructions are issued at all (and give you a link error) ifyou slip some floats in the code by mistake. > Are the FPE and TP selectors irrelevant to kernel compilation? Yes. Nicolas -- For unsubscribe information see http://sourceware.org/lists.html#faq
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