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Re: [PATCH] Add powerpc64-linux configuration options
- From: David Edelsohn <dje dot gcc at gmail dot com>
- To: Michael Meissner <meissner at linux dot vnet dot ibm dot com>, gcc-patches at gcc dot gnu dot org, bergner at vnet dot ibm dot com
- Date: Thu, 24 May 2012 19:11:53 -0400
- Subject: Re: [PATCH] Add powerpc64-linux configuration options
- References: <20120523223615.GA24175@ibm-tiger.the-meissners.org>
On Wed, May 23, 2012 at 6:36 PM, Michael Meissner
<meissner@linux.vnet.ibm.com> wrote:
> On powerpc64-linux systems that run on IBM servers, the 32-bit software
> emulation library is not built with the Red Hat and SUSE distributions, but the
> FSF sources still list it as a multilib. ?This patch adds a configuration
> option (--disable-ppc64-swfloat) to disable building this library.
>
> We've also seen some performance issues where building the multilibs with the
> -mstrict-align option causes slow downs. ?I vaguelly recall adding this option
> in the 1995 time frame, because the 603, 604 systems of the day did not handle
> unaligned accesses in little endian mode, and maybe some of the other embedded
> chips did not handle unaligned accesses at all. ?This patch also adds an option
> (--disable-ppc64-strict-align) to disable building the multilibs with
> -mstrict-align.
I thought the use of -mstrict-align for multilibs was because of some
re-use by embedded distros. That somehow one could build apps for
embedded PowerPC processors without a full embedded cross-toolchain --
just using the regular toolchain with an embedded target command line
option and the base libraries already worked. I am not suggesting that
(ab)use is appropriate, but I don't want to break embedded
environments.
I agree that strict-align does not make sense for PPC64.
I believe that is what you are accomplishing with the second version
of your patch, correct?
Thanks, David