[OE-core] why do we poison -Os?

[Xu, Dongxiao]

Hi Kumar,

The background of this commit is, when I upgraded PowerPC gcc to 4.5, tinylogin would crash with certain GCC build parameters.

The root cause for that bug is, if enabled both "-frename-registers" and "-Os" options to build tinylogin in powerpc architecture, the tinylogin/getty application will encounter segmentation fault. Other combinations like "-frename-registers and -O2" or only "-Os" will not trigger this issue.

Poky cross environment provides the "-frename-registers" parameter, however it does not provide -Os option since "--enable-target-optspace" option is disabled for powerpc gcc. The "-Os" option in tinylogin is added by its own Makefile.

This commit is to prevent the above case. If --enable-target-optspace is disabled for GCC, "-Os" should not be added by recipe.

Thanks,
Dongxiao

> -----Original Message-----
> From: Kumar Gala [mailto:galak at kernel.crashing.org]
> Sent: Wednesday, August 24, 2011 8:53 AM
> To: Xu, Dongxiao
> Cc: Patches and discussions about the oe-core layer; Khem Raj
> Subject: why do we poison -Os?
> 
> Dongxiao,
> 
> Can you explain why this was needed:
> 
> commit ce456306dad3fdf42494830011dacae213c48edf
> Author: Dongxiao Xu <dongxiao.xu at intel.com>
> Date:   Sat Sep 25 10:16:26 2010 +0800
> 
>     gcc: enable poison parameters detection
> 
>     If not configured with --enable-target-optspace, gcc will report
>     errors if there is '-Os' optimization in parameters.
> 
>     This fixes [BUGID #342]
> 
>     Also add "--enable-target-optspace" option to arm gcc configuration.
> 
>     Signed-off-by: Dongxiao Xu <dongxiao.xu at intel.com>
> 
> 
> - k