[OLPC-devel] Re: [PATCH 0/4] Compile kernel with -fwhole-program --combine

[Adrian Bunk]

On Thu, Aug 24, 2006 at 04:24:28PM +0100, David Woodhouse wrote:
>...
> Using a combination of these two compiler options for building kernel
> code leads to some useful optimisation -- especially with modules which
> are made up of a bunch of incestuous C files, where none of the global
> symbols actually _need_ to be visible outside the directory they reside
> in. File systems are a prime example of this -- on PPC64 I see a
> reduction in size of ext3.ko by 2.6%, jffs2.ko by 5%, cifs.ko by 8% and
> befs.ko by a scary 14%. Strangely, udf.ko seems to have _grown_ by 6.6%
> -- that'll probably be another optimisation bug like GCC PR28755.
>...

Looks good.  :-)

What kernel are your patches against?

2.6.18-rc4 gives me:

<--  snip  -->

...
  CHK     include/linux/version.h
  CHK     include/linux/utsrelease.h
  CC      arch/i386/kernel/asm-offsets.s
  GEN     include/asm-i386/asm-offsets.h
  HOSTCC  scripts/kallsyms
  HOSTCC  scripts/conmakehash
  HOSTCC  scripts/bin2c
make[1]: *** No rule to make target `/home/bunk/linux/linux-2.6.18-rc4/dummy.c', needed by `init/init.o'.  Stop.
make: *** [init] Error 2

<--  snip  -->
 
> dwmw2

cu
Adrian

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