size of kernel after gcc4.2 upgrade

Stefan Ehmann shoesoft at gmx.net
Fri May 25 14:02:52 UTC 2007


On Friday 25 May 2007 11:51:46 Roman Divacky wrote:
> hi
>
> I just noticed that
> spravci ~# ls -l /boot/kernel*/kernel
> -r-xr-xr-x  1 root  wheel  3389971 May 18 12:03 /boot/kernel.old/kernel*
> -r-xr-xr-x  1 root  wheel  5211345 May 25 11:47 /boot/kernel/kernel*
>
> ie. after gcc42 import the kernel size increased roughly by 60% thats
> a little too much. is there any forgotten option or something that
> makes the kernel grow so big?

While I also see an increase, it's not that much.

GENERIC from today's current, also compiled with gcc34 from ports (I had to 
delete two gcc options in sys/conf/kern.mk):

gcc34: 6530916
gcc42: 7352560
gcc34 -Os: 6074468
gcc42 -Os: 10058032

That -Os produces a much larger kernel image looks worrying. Can anyone 
confirm this? I used make COPTFLAGS="-Os -pipe" buildkernel.

For comparision, a stripped (uncompressed) debian unstable kernel (2.6.20):
gcc 3.4: 2655188
gcc 4.2: 2595948

It seems the kernel is compiled with -Os by default.
with -O2:
gcc 3.4: 3036116
gcc 4.2: 2956568

Stefan


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