More ARM binutils fuckage
Thu Dec 7 18:25:00 GMT 2006
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:
> -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:
> 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?
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