--with-arch=i486 (was Re: Merging the jh branch to trunk)
Jeremy Huntwork wrote: > On Fri, Aug 31, 2007 at 04:54:50PM -0500, Bruce Dubbs wrote: >> There also needs to be more explanation in the text interspersed with >> the instructions. For instance in "5.4. GCC-4.2.1 - Pass 1" we have: >> >> "Also, the --with-arch flag is only necessary for x86 machines." >> >> The WITHARCH variable seems to be a configure option, but I can't find >> it in ./configure --help or with a grep of configure. In any case, I >> have Pentium 4 CPU. Why do I want to use --with-arch=i486 instead of >> --with-arch=pentium4. > As Greg mentioned, by using --with-arch, we are > effectively introducing optimization into the build. Much text in the > book needs to be adjusted to show why we are using this and what is > considered 'safe'. Also, AFAIK, you could conceivably use pentium4, or > whatever fits your CPU - again, it's optimization. I want to go on record as saying `--with-arch=i486' is wrong for LFS. Note: I'm not against optimization in general. In fact, just the opposite. After all, if you're going to the trouble of building your own Linux system (and you are experienced) then you are in the perfect position to take advantage of any safe optimizations that are available. But having said that, LFS wisely does the right thing by not promoting optimization to its target audience. But getting back on topic, I personally don't buy any of the arguments for using `--with-arch=i486' listed in this ticket: http://wiki.linuxfromscratch.org/lfs/ticket/2018 "coz Debian does it" - this change is being proposed because of Glibc, and we all know defacto upstream Glibc is Red Hat/Fedora, and they do NOT do it this way. They use CFLAGS which is the proper Glibc way. See below. "you can't copy code to real i386 anyway, so why lose by default" - bogus argument. This kind of thing comes up on Fedora lists all the time. The expert's opinion is that `-mtune=' provides far more benefit than any `-march=' flag which is why they actually use `--with-cpu=' for gcc. "it's a binary compatibility issue" - bogus argument. The meaning of "ABI" is well defined. Please show any real life example of where mixing different -march= compiled x86 code makes a difference. It doesn't. I also don't buy the "entire system is built consistently" comments from the commit. The whole toolchain is actually an i686-pc-linux-gnu configured toolchain. I'm sorry, but that ain't consistent with i486. At least Debian *are* consistent because they configure their toolchain as i486-pc-linux-gnu. But the worst part IMHO has already been pinpointed by Bruce in that it will encourage novice users to play with `--with-arch=my-uber-cool-cpu'. This isn't bad in itself but it can lead to problems. For example, it has been well known for years that you cannot compile Glibc with a GCC that was configured as `--with-arch=i686' (unless you patch Glibc). It bombs out due to conflicts in GCC preprocessor macros with Glibc assembler code. This is arguably a bug in Glibc, but the fact that Glibc devs refuse to fix it indicates rather strongly that CFLAGS is the correct way to build Glibc. It also proves that CC="gcc -march=i?86" is wrong for Glibc. To clarify, if you give CFLAGS to Glibc configure, it will build .c files with those flags but it won't use them for .S files. In summary, it is MHO that configuring Glibc with CFLAGS="-march=xxx etc" is the more technically correct way and less likely to encourage novice users to hose their system. BTW, on a side note. As is already well known GCC-4.2.x enables some interesting new options, namely `generic' and `native' ie: you can pass `-mtune=native' and gcc will automatically tune for your k8 if you happen to be running Athlon64 etc. `-mtune=generic' is now the default. ie: the defaults on i686-pc-linux-gnu have now changed like this: gcc-4.1.x -march=i386 -mtune=i686 gcc-4.2.x -march=i386 -mtune=generic However, the GCC docs say this about generic: "Produce code optimized for the most common IA32/AMD64/EM64T processors. If you know the CPU on which your code will run, then you should use the corresponding -mtune option instead of -mtune=generic. But, if you do not know exactly what CPU users of your application will have, then you should use this option." Obviously, -mtune=generic is ideal for distros. But IMHO (and according to the above) -mtune=native is probably better suited for us folks. The upshot of all this is - if using GCC-4.2.x and including a `-march=' flag in the CFLAGS given to Glibc configure, it's probably best to also give an `-mtune=' flag, either "generic" or "native". Regards Greg -- http://www.diy-linux.org/ -- http://linuxfromscratch.org/mailman/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
Re: [PATCH] Add screen install attributes for final system packages
El Miércoles, 5 de Septiembre de 2007 20:41, Matthew Burgess escribió: > No comments or complaints here. We might hit merge problems between this > and the jh-branch merge, but they'll be pretty trivial to fix up, I should > think. I will look to merge the changes into the jh-branch also. We need a clean x86_64 support diff. -- Manuel Canales Esparcia Usuario de LFS nº2886: http://www.linuxfromscratch.org LFS en castellano: http://www.escomposlinux.org/lfs-es http://www.lfs-es.info TLDP-ES: http://es.tldp.org -- http://linuxfromscratch.org/mailman/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
Re: [PATCH] Add screen install attributes for final system packages
On Wed, Sep 05, 2007 at 07:52:41PM +0200, M.Canales.es wrote: > If there is no objetions about that additions, I will commit the changes this > weekend. +1 > Comments, complaints? Currently, my biggest complaint is that I have no ice cream. :( -- JH -- http://linuxfromscratch.org/mailman/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
Re: [PATCH] Add screen install attributes for final system packages
On Wed, 5 Sep 2007 19:52:41 +0200, "M.Canales.es" <[EMAIL PROTECTED]> wrote: > http://linuxfromscratch.org/pipermail/lfs-dev/2007-July/059682.html > http://linuxfromscratch.org/pipermail/lfs-dev/2007-July/059687.html > > If there is no objetions about that additions, I will commit the changes > this > weekend. > > Comments, complaints? No comments or complaints here. We might hit merge problems between this and the jh-branch merge, but they'll be pretty trivial to fix up, I should think. Thanks, Matt. -- http://linuxfromscratch.org/mailman/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
Re: [PATCH] Add screen install attributes for final system packages
El Sábado, 21 de Julio de 2007 01:42, Dan Nicholson escribió: > Another jhalfs helper. As has been discussed before, it would be nice to > mark the screen sections with an attribute to announce that it will be > installing to the system rather than just working in the source/build > tree. Manuel suggested adding the attribute userlevel="install", so I've > done that for the Ch. 6 packages and the kernel in Ch. 8. Now that LFS-6.3 has been released and we are just openning a new 7.0 milestone, I think that is the best momment to implement that XML additions, if they are accepted. For reference, the propossals was made on this posts: http://linuxfromscratch.org/pipermail/lfs-dev/2007-July/059682.html http://linuxfromscratch.org/pipermail/lfs-dev/2007-July/059687.html If there is no objetions about that additions, I will commit the changes this weekend. Comments, complaints? -- Manuel Canales Esparcia Usuario de LFS nº2886: http://www.linuxfromscratch.org LFS en castellano: http://www.escomposlinux.org/lfs-es http://www.lfs-es.info TLDP-ES: http://es.tldp.org -- http://linuxfromscratch.org/mailman/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
Re: Merging the jh branch to trunk
On Wed, 5 Sep 2007 17:02:40 + (UTC), Jeremy Huntwork <[EMAIL PROTECTED]> wrote: > Matthew Burgess linuxfromscratch.org> writes: >> Does this sound sane to everyone? If so, I'll endeavour to complete the > patch > series as soon as possible and >> post it here for review. > > How's this coming? Need any help? Stalled at the minute, thanks to two late nights at work this week! Should be able to get it out for review tomorrow evening. Regards, Matt. -- http://linuxfromscratch.org/mailman/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
Re: Merging the jh branch to trunk
Matthew Burgess linuxfromscratch.org> writes: > Does this sound sane to everyone? If so, I'll endeavour to complete the patch series as soon as possible and > post it here for review. How's this coming? Need any help? -- JH -- http://linuxfromscratch.org/mailman/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
Re: Xen-LFS hint
- Original Message - From: "Bryan Kadzban" <[EMAIL PROTECTED]> To: "LFS Developers Mailinglist" Sent: Wednesday, September 05, 2007 1:05 PM Subject: Re: Xen-LFS hint > I'm going to guess that that's because your Gmail account is not the > one > that you've subscribed to the list you're trying to post to. I've > been > hit with that too. Subscribe it, and I'm guessing it'll work fine. Hi Bryan. Wrong guess. When I changed email subscription account to Gmail one happened so I changed it back to another one. Luca -- http://linuxfromscratch.org/mailman/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
Re: Xen-LFS hint
-BEGIN PGP SIGNED MESSAGE- Hash: RIPEMD160 FYI: Luca wrote: > P.S. Posts sent via my Gmail account are classified and rejected as > spam I'm going to guess that that's because your Gmail account is not the one that you've subscribed to the list you're trying to post to. I've been hit with that too. Subscribe it, and I'm guessing it'll work fine. -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.7 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFG3o2QS5vET1Wea5wRA4lLAKDOfCPngOU6HXG4o1z6fH+JYIqjegCfQErc LDVpcenBu4QwSTRE3pAIHDQ= =Yonm -END PGP SIGNATURE- -- http://linuxfromscratch.org/mailman/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
Xen-LFS hint
Hello. Sorry to say it'll take me more time than estimated. I've got to publish a paper and waiting new hardware delivery (to be used to test and write the hint). Regards, Luca P.S. Posts sent via my Gmail account are classified and rejected as spam -- http://linuxfromscratch.org/mailman/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
