From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from az33egw02.freescale.net (az33egw02.freescale.net [192.88.158.103]) by ozlabs.org (Postfix) with ESMTP id 01C0767A42 for ; Fri, 6 May 2005 01:12:52 +1000 (EST) In-Reply-To: <20050505142354.GZ1221@smtp.west.cox.net> References: <20050505142354.GZ1221@smtp.west.cox.net> Mime-Version: 1.0 (Apple Message framework v619.2) Content-Type: text/plain; charset=ISO-8859-1; format=flowed Message-Id: From: Kumar Gala Date: Thu, 5 May 2005 10:12:42 -0500 To: "Tom Rini" Cc: linuxppc-dev@ozlabs.org Subject: Re: [PATCH] Set cpu explicitly in kernel compiles List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On May 5, 2005, at 9:23 AM, Tom Rini wrote: > On Thu, May 05, 2005 at 09:00:50AM -0500, Kumar Gala wrote: > > > > On May 5, 2005, at 7:24 AM, Dan Malek wrote: > > > > > > > > > > >On May 5, 2005, at 1:22 AM, Paul Mackerras wrote: > > > > If you think we should have -mcpu=3Dxxx on the command line for=20= > 4xx, > > > > 44x, 8xx, etc., then that's fine, but that is a separate = problem > > >from > > > > what my patch was addressing (one which my patch might make it > > >easier > > > > to fix, though). > > > > > >I think that is exactly what we want, although I don't know how=20 > that is > > > separate from the patch you sent.? My original comment was the=20 > patch > > > fixes the problem for only one of the cpu cores, not all of = them.? > > >Which > > > then led into the subsequent suggestion of making the biarch work > > > like the past compilers, and we must specific the flags for = POWER4 > > > instead of the other way around.? Without explicit -mcpu flags,=20= > the > > > existing compiler behavior is just fine .....? but, I guess I'd = be > > >standing > > > in the way of progress to want this :-) > > > > I agree with Dan here.=A0 I think we should go ahead and extend the=20= > patch > > to set -mcpu and -mtune flags for the list of processors we have in > > "Processor Type".=A0 If I'm building a kernel for e500 or 4xx I = might=20 > as > > well get a kernel that is tuned a bit more for the subarch.=A0 > > This is fine. > > > Additionally, there should be some expert override ability, so if I > > really want to do -mcpu=3D7455 -mtune=3D7455 I can. > > Gack, no!=A0 It's quite a pain to go from CONFIG_FOO=3D"string" into=20= > useable > Makefile bits that the one we did have back in 2.4 is gone.=A0 That = also > implies gcc finally knows something about these cores that might be > useful, which I don't think is the case, nor is it likely to be.=A0 = But=20 > if > we did want it, we'd probably go the route x86 has. I'm not saying it has to be done via a CONFIG option, all I'm saying is=20= if I want to explicitly use GCC then I would hope we could somehow=20 disable it being override. - kumar=