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).
Regards,
-- Luc Van Oostenryck
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