Re: Setting CPUTYPE and CFLAGS in make.conf
On Tue, 8 Apr 2008 13:14:45 -0700 David Allen [EMAIL PROTECTED] wrote: The advice I've read in several posts on the subject involve everything from setting one, setting both, to ignoring both, sometimes with the =? notation and sometimes without. And then, I've read comments that suggest when compiling the kernel, for example, both are ignored, and default values (tucked away somewhere) are always applied. IIRC, the handbook recommends at least setting CPUTYPE. Avoid setting CFLAGS unless you have a good reason - Gentoo documentation has a lot to answer for. CPUTYPE causes -march to be applied, so it can affect compatibility. AFAIK both setting do affect world and kernel because CFLAGS can cause a build to fail, and I've seen matching march settings in kernel builds. Or are those settings relevant to the compilation process only? Or to both the compilation process and the actual performance of the binary? It can be either, -O2 is related to execution, -pipe speeds-up compilation. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Setting CPUTYPE and CFLAGS in make.conf
On Wed, Apr 9, 2008 at 10:44 AM, RW wrote: On Tue, 8 Apr 2008 13:14:45 -0700 David Allen wrote: The advice I've read in several posts on the subject involve everything from setting one, setting both, to ignoring both, sometimes with the =? notation and sometimes without. And then, I've read comments that suggest when compiling the kernel, for example, both are ignored, and default values (tucked away somewhere) are always applied. IIRC, the handbook recommends at least setting CPUTYPE. Avoid setting CFLAGS unless you have a good reason - Gentoo documentation has a lot to answer for. CPUTYPE causes -march to be applied, so it can affect compatibility. AFAIK both setting do affect world and kernel because CFLAGS can cause a build to fail, and I've seen matching march settings in kernel builds. Or are those settings relevant to the compilation process only? Or to both the compilation process and the actual performance of the binary? It can be either, -O2 is related to execution, -pipe speeds-up compilation. Thank you for your reply. It's starting to make a lot more sense. Just to confirm, then, if there's no CPUTYPE set, I can then set up a build server on an Opteron box, for example, to build world, kernel and ports binaries that can then be installed on my Thinkpad or a PIII box? ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Setting CPUTYPE and CFLAGS in make.conf
On Wed, Apr 09, 2008 at 11:35:51AM -0700, David Allen wrote: [...] Thank you for your reply. It's starting to make a lot more sense. Just to confirm, then, if there's no CPUTYPE set, I can then set up a build server on an Opteron box, for example, to build world, kernel and ports binaries that can then be installed on my Thinkpad or a PIII box? Yes, provided they use the same architectures, eg: i386 -- Jonathan Chen [EMAIL PROTECTED] We laugh in the face of danger, we drop icecubes down the vest of fear - Edmond Blackadder III ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Setting CPUTYPE and CFLAGS in make.conf
On Wed, Apr 09, 2008 at 11:35:51AM -0700, David Allen wrote: Avoid setting CFLAGS unless you have a good reason - Gentoo documentation has a lot to answer for. CPUTYPE causes -march to be applied, so it can affect compatibility. AFAIK both setting do affect world and kernel because CFLAGS can cause a build to fail, and I've seen matching march settings in kernel builds. Or are those settings relevant to the compilation process only? Or to both the compilation process and the actual performance of the binary? It can be either, -O2 is related to execution, -pipe speeds-up compilation. Thank you for your reply. It's starting to make a lot more sense. Just to confirm, then, if there's no CPUTYPE set, I can then set up a build server on an Opteron box, for example, to build world, kernel and ports binaries that can then be installed on my Thinkpad or a PIII box? Only if they use the same architecture! If your opteron is running amd64, its binaries won't run on a pIII, which can only run the i386 architecture. If you read through /usr/src/share/mk/bsd.cpu.mk you can see the different CPU types and the effect they have on build parameters. E.g. on the i386 architecture, if no CPUTYPE is set, the CPU type is set to i486, which is the lowest common denominator that gcc supports. Roland -- R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) pgplMUMLIBvOx.pgp Description: PGP signature
Re: Setting CPUTYPE and CFLAGS in make.conf
On Wed, 9 Apr 2008 11:35:51 -0700 David Allen [EMAIL PROTECTED] wrote: Thank you for your reply. It's starting to make a lot more sense. Just to confirm, then, if there's no CPUTYPE set, I can then set up a build server on an Opteron box, for example, to build world, kernel and ports binaries that can then be installed on my Thinkpad or a PIII box? CPUTYPE=pentiumpro is a good choice for mainstream i386 processors since it's the common ancestor of the Athlon and modern Pentium series - the exceptions are some of the low-power cpus for small form-factor motherboards. The default is i486, which should handle anything. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Setting CPUTYPE and CFLAGS in make.conf
The advice I've read in several posts on the subject involve everything from setting one, setting both, to ignoring both, sometimes with the =? notation and sometimes without. And then, I've read comments that suggest when compiling the kernel, for example, both are ignored, and default values (tucked away somewhere) are always applied. IIRC, the handbook recommends at least setting CPUTYPE. My question isn't a holy grail type of quest for maximised performance, but concerns the meaning of those settings with respect to building world, building kernel and anything in ports. Put another way, I'm not a computer science major, but do have different systems that I compile for, and I'd like to have a better understand WTF I'm really doing. For example, what is the difference, if any, between a binary compiled with: CPUTYPE=opteron CFLAGS=-O -pipe compares with compiling it using: CPUTYPE=pentium3 CFLAGS= compares with compiling it using what I think are the universal defaults of: CPUTYPE= CFLAGS=-O2 -fno-strict-aliasing -pipe that get applied if the make.conf is blank? Can the resulting binary be run on each other's system? Or is it simply optimised to run on one, versus another? Or are those settings relevant to the compilation process only? Or to both the compilation process and the actual performance of the binary? Or should I be taking the dog for a nice long walk instead of watching scrolling compiler output? ;-) If someone could take a moment to explain in moderately technical terms what all the above means, or suggest a source for further reading, I'd be grateful. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
