Default ISA/tuning flags for GCC, --enable-kernel= level for glibc

[Jakub Jelinek]

On Mon, Jan 26, 2009 at 02:37:28PM +0100, Dan Horák wrote:
> There is no plan for 31-bit Fedora on s390 AFAIK, and regarding 64-bit
> please take a look at https://bugzilla.redhat.com/show_bug.cgi?id=463830

If we are to use -march=z9-109 -mtune=z10 instead of -march=z900 -mtune=z10
for s390 -m31 and -m64, then releng is important.  Aren't the current
mainframes used for Fedora (and RHEL) building z990?  If yes, then this
can't be switched until they are z9-109 or z10 based.

> > we could just -mcpu=ultrasparc -mtune=ultrasparc always, given that the
> > 32-bit support is being dropped.
> 
> The general question is what should be the relation between GCC defaults
> and parameters set in the rpm build macros.

Certainly redhat-rpm-config macros shouldn't be weaker than what we default
in gcc (say if gcc defaults to -march=i486 -mtune=generic, then
redhat-rpm-config shouldn't override this to -march=i386 -mtune=generic).

	Jakub