On Mon, Sep 17, 2001 at 07:00:00AM +0000, Ingo Molnar wrote: > * Denys Vlasenko <dvlas...@redhat.com> wrote: > > > What do you guys think about this? I think we should seriously > > > consider relaxing our alignment defaults. > > > > Looks like nobody objected. I think it's ok to submit > > this patch for real. > > Yeah, so my plan is to apply the following three changes from that > discussion: > > --- tip.orig/arch/x86/Makefile > +++ tip/arch/x86/Makefile > <at> <at> -77,6 +77,15 <at> <at> else > KBUILD_AFLAGS += -m64 > KBUILD_CFLAGS += -m64 > > + # Pack jump targets tightly, don't align them to the default 16 > bytes: > + KBUILD_CFLAGS += -falign-jumps=1 > + > + # Pack functions tightly as well: > + KBUILD_CFLAGS += -falign-functions=1 > + > + # Pack loops tightly as well: > + KBUILD_CFLAGS += -falign-loops=1 > + > # Don't autogenerate traditional x87 instructions > KBUILD_CFLAGS += $(call cc-option,-mno-80387) > KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
It looks like the patch you applied to the tip tree only included one of these (-falign-junmps=1), not the other two. Also, you've only applied these to 64-bit; could you please apply them to both 32-bit and 64-bit, since many embedded systems aiming for small code size use 32-bit? (Unless 32-bit already defaults to these.) Have you considered including -falign-labels=1 as well? Does that make a difference on top of the other three. Finally, it looks like -Os already implies all four of those, as well as a few others, so unfortunately the code size benefits don't actually apply to the tiniest kernels, which already effectively incorporate this change. Oh well. - Josh Triplett -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
