Re: [PATCH 4/6] Add support for LZO-compressed kernels for ARM

Matthieu CASTET
2009-08-07T11:50:23Z

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, ...).

Matthieu