[Clfs-dev] EGLIBC x86 is special?

[Andrew Bradford]

On Fri, Jul 12, 2013, at 12:43 PM, William Harrington wrote:
> 
> On Jul 12, 2013, at 6:35 AM, Andrew Bradford wrote:
> 
> > For x86 32 bit and x86 32 bit portion of multilib but not for any  
> > other
> > arch including x86_64 there's the addition of:
> >
> > CFLAGS="-march=$(cut -d- -f1 <<< $CLFS_TARGET32) -mtune=generic -g - 
> > O2"
> 
> I can't find an archive of Greg's original post and the LFS mailing  
> list archive is still not available. But I'm sure it stemmed from this:
> 
> http://www.mail-archive.com/lfs-dev@linuxfromscratch.org/msg10910.html

OK, but when setting -march= to i386, i486, or i686 isn't the goal to
not support a processor that's older?  Isn't that the point of choosing
your target?  If I'm choosing my triplet to be i686-pc-linux-gnu then
don't I implicitly choose to not support running the code generated on
an i386 machine?  Passing the -mtune=generic may not even do anything
useful for 32 bit x86 any more, Linux doesn't even support i386 as an
arch these days, since 3.8 (which is in the main book).  If you want to
run on any processor newer than i386 you pick your triplet as
i386-pc-linux-gnu and go from there.

Plus, why is 32 bit x86 the only place that -g and -O2 are passed?  Do
we really need those defined here?
I know there's mention that -O3 causes issues sometimes but that was
like 6+ years ago on much older gcc and glibc, let alone other software
that would crash.

I guess the true test is to just try and see what happens.  They just
don't seem necessary to me.
Thanks,
Andrew