So the hardfp on Fedora bring up is happening today. Newer ARMv7 chipsets can basically run in two modes that aren’t compatible. The current and most widely used variant is softfp which uses a software based FPU. The newer and cooler (read faster) variant ARMv7 chips contain a hardware FPU but the GNU open tool chain has only recently got to the stage where its all supported. All the needed components should be in Fedora 15 with one of the key pieces being gcc 4.6.
What does it mean for ARM on Fedora…. in the short term likely not much. The older ARMv5tel platform support isn’t going anywhere. Its a little like mainline x86_64 vs i386 platforms, except you can’t run 5tel binaries on 7hl distributions (although you can run an entire 5tel distro on ARMv7 hardware. Also with the hardfp stack support being very new there will likely be a number of weird and interesting bugs that will make it not for the faint of heart.
With luck this should change in the Fedora 16 time frame and with luck we should be in sync on both armv7l (hardfp) and armv5tel (softfp) in the Fedora 16 timeframe for a near in-sync release.
Let me clarify it a bit:
– software fp emulation doesn’t use the FPU at all
– softfp uses the FPU, but it passes data in the integer registers.
– hardfp uses the FPU uses the floating point registers of the ARM core.
By the way, some ARMv5 chipsets (eg. OMAP2) also support hardfp.
Yes, I’m aware some ARMv5 chipsets support hardfp but it wasn’t required as part of the specification and it was VFPv2 as opposed VFPv3 like ARMv7.