Re: Possibility of adding -march=native to x86

[Adrian Bunk <bunk@kernel.org>]

On Thu, Oct 25, 2007 at 10:30:09PM +0100, Michael Lothian wrote:
> On 25/10/2007, Gabriel C <nix.or.die@googlemail.com> wrote:
> > Michael Lothian wrote:
> > >> The MPENTIUM4 option does not only set -march=pentium4, it also enables
> > >> several other options in arch/i386/Kconfig.cpu resulting in better
> > >> performance.
> > >
> > > How about an autodetect to set the right options here too using cpuid?
> > >
> > > With a warning of course that the code produced will be specifically
> > > for the native cpu that it's compiled on.
> >
> > And kill off all Distro kernels right ? IMO to set that auto magically is bad.
> >
> > Regards,
> >
> > Gabriel
> >
> Yes for something like a distro kernel it is bad but as I said before
> this isn't what this is for.
> 
> Eventually it would be nice to to a make localkernel and for a
> customised kernel to be build compiling in all pci / pci express
> drivers into the kernel and all usb devices as modules.
> 
> Auto magically detecting the cpu would be part of that
> 
> I hate getting a new piece of kit and then have to figure out from
> lspci which options need to be turned on and the the really iritation
> part of finding the option in make menuconfig

What exactly is irritating?
Please name the problems so that they can be fixed.

> Detecting the cpu and using march=native could be all part of that

You don't need march=native for this.

You have to set the right config option for your CPU and you 
automatically get the right compiler options.

> Mike

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
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       "Only a promise," Lao Er said.
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