On Fri, Aug 07, 2009 at 03:27:00PM +0200, Matthieu CASTET wrote : > Albin Tonnerre a écrit : > > On Fri, Aug 07, 2009 at 01:50:03PM +0200, Matthieu CASTET wrote : > >> Albin Tonnerre a écrit : > >>> On Fri, Aug 07, 2009 at 11:36:56AM +0200, Alain Knaff wrote : > >>>> On 08/07/09 11:24, Albin Tonnerre wrote: > >>>>> Regards, > >>>> Could it be that the patches that remove division (zutil.h and inflate.c) > >>>> have somehow not been applied? > >>> Indeed, they've not been applied. However, I'd rather try to understand why > >>> exactly this is an issue when compiling with -Os and not -O2 instead of working > >>> around it by removing the divisions. > >> Look at the generated code. > >> Arm doesn't have division instruction. > >> May be at -Os gcc emit a call to the software division, but at -O2 it > >> manage to optimise the division (transform it in shift, inline some > >> builtin, ...). > > Yes, I figured that out. What I don't get, though, is that it fails while the > > software division symbol (__aeabi_uidivmod here) does seem to be provided by > > libgcc. > AFAIK we don't link the kernel with libgcc. > That's why the kernel provide __aeabi_* in arch/arm/lib That's true for the actual kernel image, but not for the bootstrap code we use when compiling compressed kernels. arch/arm/boot/compressed/Makefile uses libgcc, unless I'm overlooking something here: arm-unknown-linux-uclibcgnueabi-ld -EL --defsym zreladdr=0x20008000 --defsym initrd_phys=0x20410000 --defsym params_phys=0x20000100 -p --no-undefined -X /home/albin/x-tools/arm-unknown-linux-uclibcgnueabi/lib/gcc/arm-unknown-linux-uclibcgnueabi/4.3.2/libgcc.a -T arch/arm/boot/compressed/vmlinux.lds arch/arm/boot/compressed/head.o arch/arm/boot/compressed/piggy.gzip.o arch/arm/boot/compressed/misc.o -o arch/arm/boot/compressed/vmlinux Regards, -- Albin Tonnerre, Free Electrons Kernel, drivers and embedded Linux development, consulting, training and support. http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
