On Tue, Jun 20, 2017 at 06:24:32PM +0200, Luc Van Oostenryck wrote:
> On Tue, Jun 20, 2017 at 04:49:39PM +0100, Will Deacon wrote:
> > On Tue, Jun 20, 2017 at 02:24:43PM +0200, Luc Van Oostenryck wrote:
> > > When using sparse on the arm64 tree we get many thousands of
> > > warnings like 'constant ... is so big it is unsigned long long'
> > > or 'shift too big (32) for type unsigned long'. This happens
> > > because by default sparse considers the machine as 32bit and
> > > defines the size of the types accordingly.
> > >
> > > Fix this by passing the '-m64' flag to sparse so that
> > > sparse can correctly define longs as being 64bit.
> > >
> > > CC: Catalin Marinas <catalin.marinas@xxxxxxx>
> > > CC: Will Deacon <will.deacon@xxxxxxx>
> > > CC: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > > Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
> > > ---
> > > arch/arm64/Makefile | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> > > index f839ecd91..15d6c1476 100644
> > > --- a/arch/arm64/Makefile
> > > +++ b/arch/arm64/Makefile
> > > @@ -62,7 +62,7 @@ LD += -EL
> > > UTS_MACHINE := aarch64
> > > endif
> > >
> > > -CHECKFLAGS += -D__aarch64__
> > > +CHECKFLAGS += -D__aarch64__ -m64
> >
> > Looks fine to me, but just wondering whether or not we should also be
> > passing something to indicate the endianness of the target. Does sparse care
> > about that?
>
> Yes, we should. sparse doesn't care per-se but some macros, structures
> or whole portion of code may depends on '__{LITTLE,BIG}_ENDIAN__'
> being defined or not, for example (but I don't think it will make
> a big difference, at least nothing like the 629904 'constant is so big'
> warnings we have now due to the missing -m64).
>
> For this, you have two possibilities:
> 1) just doing something like PPC:
> +ifdef CONFIG_CPU_BIG_ENDIAN
> +CHECKFLAGS += -D__BIG_ENDIAN__
> +else
> +CHECKFLAGS += -D__LITTLE_ENDIAN__
> +endif
> This will work now. I can't send you a proper patch if you wish.
>
> 2) a cleaner solution, IMO, would be to teach sparse about
> -mlittle-endian/-mbig-endian. In fact I already wrote the patch
> earlier today. But of course, you will need to wait for the patch
> to reach sparse's master and then compile sparse yourself or wait
> for a new release (which shouldn't take much long, though).
If you do that, you could also teach it that AArch64 is 64-bit ;)
Will
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