Messages in this thread | | | Date | Thu, 7 Sep 2006 00:37:48 +0200 | From | Adrian Bunk <> | Subject | Re: [2.6 patch] re-add -ffreestanding |
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On Wed, Aug 30, 2006 at 07:39:05PM +0100, Russell King wrote: > On Wed, Aug 30, 2006 at 08:13:58PM +0200, Andi Kleen wrote: > > On Wednesday 30 August 2006 19:57, Adrian Bunk wrote: > > > I got the following compile error with gcc 4.1.1 when trying to compile > > > kernel 2.6.18-rc4-mm2 for m68k: > > > > If anything then -ffreestanding needs to be added to arch/m68k/Makefile > > (assuming it doesn't compile at all right now) > > Looking at the effect of -ffreestanding on ARM, it appears that on one > hand, the overall image size is reduced by 0.016% but we end up with worse > code - eg, strlen() of the same string in the same function evaluated > multiple times vs once without -ffreestanding. > > The difference probably comes down to the lack of __attribute__((pure)) > on our string functions in linux/string.h. > > If we are going to go for -ffreestanding, we need to fix linux/string.h > in that respect _first_.
We are talking about reverting the patch that removed -ffreestanding, and that broke at least two architectures although it wrongly claimed it would have been a safe patch.
I agree that there is room for improvement at our string functions, but small optimizations like the ones you are mentioning are not much when talking about reverting a patch that is both theoretically wrong and has proven practically to cause problems.
> Russell King
cu Adrian
--
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