Re: [PATCH] ARM: Use udiv/sdiv for __aeabi_{u}idiv libraryfunctions

From: Russell King - ARM Linux
Date: Fri Nov 08 2013 - 11:54:54 EST


On Fri, Nov 08, 2013 at 12:50:04PM +0100, Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 19:34 Thu 07 Nov , Rob Herring wrote:
> > On Thu, Nov 7, 2013 at 1:20 PM, Stephen Boyd <sboyd@xxxxxxxxxxxxxx> wrote:
> > > If we're running on a v7 ARM CPU, detect if the CPU supports the
> > > sdiv/udiv instructions and replace the signed and unsigned
> > > division library functions with an sdiv/udiv instruction.
> >
> > [snip]
> >
> > > diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
> > > index bd454b0..6ed6496 100644
> > > --- a/arch/arm/lib/Makefile
> > > +++ b/arch/arm/lib/Makefile
> > > @@ -15,6 +15,9 @@ lib-y := backtrace.o changebit.o csumipv6.o csumpartial.o \
> > > io-readsb.o io-writesb.o io-readsl.o io-writesl.o \
> > > call_with_stack.o
> > >
> > > +lib-$(CONFIG_CPU_V7) += div-v7.o
> > > +CFLAGS_div-v7.o := -march=armv7-a
> >
> > Won't this fail to build if the compiler doesn't have armv7-a support.
> > Perhaps we don't care about compilers that old.
>
> use the propoer compiler to compile a armv7 kernel

It's probably about time to get rid of the conditionals for this in
the main arch/arm/Makefile actually - some of those date back some
10 or so years. That's something for the v3.14 merge window.
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