Albert ARIBAUD <albert.arib...@free.fr> writes: > Le 19/02/2011 15:06, Alexander Holler a écrit : >> Am 19.02.2011 14:51, schrieb Albert ARIBAUD: >>> Le 19/02/2011 14:25, Måns Rullgård a écrit : >>> >>>>> So whats the reasoning to use -msoft-float as it is currently done? To >>>>> confuse people? ;) >>>> >>>> I guess it's there to make sure no floating-point instructions make it >>>> into u-boot, even though floats are not used in the code. Perhaps >>>> someone was paranoid. >>> >>> I think also that there is no choice but to have a float option for ARM >>> C, either 'soft' or 'hard' (or 'softfp', actually, which is 'hard' with >>> the 'soft' calling conventions), because the C compiler does not allow >>> 'no floats', and anyway the C language *requires* to have some sort of >>> float support. >> >> As it is on every platform. > > Indeed. > >>> Actually if you don't specify any float option, the C toolchain will >>> choose one, which is just the same in the end: *some* float option is >>> chosen. >> >> Every compiler has dozens of options which are set to a default value. > > Granted. But not all of them relate to hardware which may or may not be > available. > >>> And since some option must be chosen, I prefer that U-Boot make the >>> explicit decision, and choose soft float for the reasons I already >>> exposed. >> >> I don't see any reason to explicitly set an option for something which >> isn't used, but I know of many reasons to avoid such. ;) > > At least there is one reason for having -msoft-float even though no > floating point should be used in U-Boot : it helps catching cases where > some code in U-Boot tries to use hard float. :)
There is one further complication here. If the compiler was built with -mfpu=neon as default, it might emit neon instructions for pure integer code. For the purpose of this discussion, such instructions should still be regarded as floating-point since they are tied to the VFP. Such code generation is disabled by -msoft-float. -- Måns Rullgård m...@mansr.com _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
