On Friday 19 June 2009 18:20:53 Florian Fainelli wrote: > Le Tuesday 09 June 2009 16:00:47 Michael Buesch, vous avez écrit : > > On Monday 08 June 2009 21:35:05 matthieu castet wrote: > > > Michael Buesch wrote: > > > > On Sunday 07 June 2009 11:28:50 matthieu castet wrote: > > > >> Hi, > > > >> > > > >> I wonder with openwrt for bcm47xx is not build with "-msoft-float". > > > >> The cpu doesn't have fpu and the current floating code get emulated by > > > >> the kernel emulator instead of using the gcc emulation support (that > > > >> is cheaper because there is no kernel trap). > > > > > > > > Well, I guess on a typical bcm47xx setup there's hardly any application > > > > that uses floating point math. > > > > > > note that dropbear seems to use some, but that not critical. > > > > > > > Does -msoft-float increase the binary/image size? If so, I'd > > > > vote for _not_ adding -msoft-float. If it doesn't make a size > > > > difference, we should probably add it. > > > > > > That shouldn't increase size of application that don't use float. > > > I did a quick test with dropbear that contain very few float. > > > Here are the results (sfloat means -msoft-float, sgcc mean > > > -shared-libgcc) > > > > > > > > > $size /tmp/dropbear* > > > text data bss dec hex filename > > > 226924 4252 1744 232920 38dd8 /tmp/dropbear > > > 234719 4328 1744 240791 3ac97 /tmp/dropbear_sfloat > > > 220781 4192 1744 226717 3759d /tmp/dropbear_sfloat_sgcc > > > 219956 4152 1744 225852 3723c /tmp/dropbear_sgcc > > > > > > As you can see with a static libgcc the size of the softfloat binary > > > increase (8k) because all float emulation code is duplicated in the > > > binary. With a shared libgcc the softfloat binary is smaller, the > > > increase size is less than 1k. > > > > > > I don't know the impact for whole binary. I should try to build a > > > typical bcm47xx setup and see the impact. > > > > Ok. It still smells like we're trying to solve a problem that does not > > exist. Is the performance of any app increased in real life? > > We can still allow soft-float to be used in the toolchain, and keep the > in-kernel FPU emulator for compatibility, but then we will loose some space.
Yeah well. That's my question. Do we actually gain performance or do we only loose some space? If we do _not_ gain performance, it certainly is not a good idea to waste space. -- Greetings, Michael. _______________________________________________ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/mailman/listinfo/openwrt-devel
