Re: Building packages and compiler flags
On Thu, Apr 14, 2005 at 07:15:45PM +0200, Wolfgang Pfeiffer wrote:
> On Thu, Apr 14, 2005 at 03:47:35PM +0200, Carsten Friede wrote:
> > Hi.
> >
> > Is it possible to activate specific compiler flags, when building
> > packages from source, eg. for the AltiVec, to improve performance?
>
> Not being sure whether you need to know the flags, or how to use them
> with the Debian package build system, like make-kpkg etc.
>
> If you simply want some flags: From my bookmarks:
>
> <http://www.freehackers.org/gentoo/gccflags/flag_gcc3.html>
> <http://www.freehackers.org/gentoo/gccflags/flag_gcc3opt.html>
> <http://gcc.gnu.org/onlinedocs/gcc/RS_002f6000-and-PowerPC-Options.html#RS_002f6000-and-PowerPC-Options>
> <http://linuxreviews.org/howtos/compiling/safe-cflags/>
> <http://linuxreviews.org/howtos/compiling/unsafe-cflags/#toc1>
>
> But I'd have a look at the sources you want the flags being fed into,
> and whether the flags described on the pages above are not already
> used there ... :)
>
> If you want to know how to feed the flags to, e.g, make-kpkg for a
> "live" compile, then I can't help. Sorry ..
Hah, by accident, when trying to learn something for kernel compiles I
stumbled over this in /usr/share/doc/kernel-package/README.gz (which
is part of, IINM, "kernel-package")
---------------------------------------------------------
% MAKEFLAGS="CC=gcc-3.2" make-kpkg ...
--------------------------------------------------------
So it seems you can feed flags directly into Debian build processes, on
the command line ... but I don't know yet the syntax if there's more than
one flag to be fed to, e.g., make-kpkg ...
[Minutes later:]
After some very fast glance over some Google results it looks like
there is a solution for multiflags-on-command-line:
Example:
MAKEFLAGS="CC=amd64-linux-gcc V=1 HOSTCC=gcc-3.4"
[from:
<http://debian-amd64.alioth.debian.org/patches/current/kernel-image-2.6.8-amd64_2.6.8-12.0.0.1.gcc4.patch>
.... and I can't gauge whether the code on this page is correct or not]
I just played a bit with it:
$ export MAKEFLAGS=CC=gcc-3.2 CXXFLAGS="-O3 -pipe -mpowerpc-gfxopt"
$ env | grep mpower
CXXFLAGS=-O3 -pipe -mpowerpc-gfxopt
$ env | grep gcc
MAKEFLAGS=CC=gcc-3.2
$
:)))))
Please:
Don't take the flags above as valid ones: I was just playing .. Don't
do the above, if you need some serious work get done :) ... And wait
for those here being able to confirm I wasn't writing bs .. :)
At any rate it seems to look good ... perhaps ask Google for more ... :)
Good luck, and please let us know if you know more than I do currently ...
And thanks for asking your question: I was looking for the answer
since some time ago ... simply forgot about it, only being re-minded
to it by your email today ... :)
Regards
Wolfgang
--
Wolfgang Pfeiffer
http://profiles.yahoo.com/wolfgangpfeiffer
Reply to: