Jakub Jelinek píše v Po 26. 01. 2009 v 11:15 +0100: > Hi! > > dist-f11-gcc44 currently has gcc 4.4.0-0.X packages, which are almost ready > for moving into dist-f11, but before doing that, I'd like to discuss > defaults. gcc on most arches has a switch to select which ISA it can assume > (i.e. what minimum CPU will gcc compiled code run on) and a separate option > to tune for the same or other CPU. Currently in Fedora the tuning is > I believe: > ISA tuning > i386 -march=i386 -mtune=generic > x86_64 -march=x86-64 -mtune=generic > ppc lowest -mtune=power6 > ppc64 lowest -mtune=power6 > s390 -march=g5 -mtune=z9-109 > s390x -march=z900 -mtune=z9-109 > ia64 lowest -mtune=itanium2 > sparc -mcpu=v7 -mtune=v7 > sparcv9 -mcpu=v7 -mtune=v7 > sparc64 -mcpu=ultrasparc -mtune=ultrasparc > > plus redhat-rpm-config tweaks something (-fasynchronous-unwind-tables > and -mminimal-toc tweaking should IMHO remain in redhat-rpm-config): > i686 -march=i686 -mtune=generic > sparc -mcpu=v7 -mtune=ultrasparc > sparcv9 -mcpu=ultrasparc -mtune=ultrasparc > > The question is, do we want to change anything on this for F11? > E.g. I believe Fedora hasn't shipped an i386 or i486 kernel for years, > and especially the -march=i386 vs. -march=i486 difference is significant > (-march=i386 doesn't have sufficient atomic instructions). The only > -lpthread library we are using is NPTL and that doesn't support i386 > anyway, so I think we should either use -march=i486 or -march=i586 > (the latter has 8 byte compare and swap instruction) as the default, > when -march= isn't specified. > Similarly, I wonder what CPUs we want to support in Fedora for PowerPC, > if e.g. -march=power4 default wouldn't be possible. On s390, is somebody > running Fedora on some 31-bit hw still (G5/G6), or could we safely default to > -march=z900 for -m31 as well and say -mtune=z10? On sparc I guess There is no plan for 31-bit Fedora on s390 AFAIK, and regarding 64-bit please take a look at https://bugzilla.redhat.com/show_bug.cgi?id=463830 > we could just -mcpu=ultrasparc -mtune=ultrasparc always, given that the > 32-bit support is being dropped. The general question is what should be the relation between GCC defaults and parameters set in the rpm build macros. Dan -- fedora-devel-list mailing list fedora-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-devel-list
