[Buildroot] Problem with iperf

Rex Ashbaugh rexa at xeratech.com
Thu Feb 28 17:21:31 UTC 2008 

hmm, looks like "_udivsi3_s.o" (built with hardware FP) was built prior to
your new configuration selection of software FP.
you may need to clean buildroot, or start over.
just in case, my suggestion is you probably want to preserve the buildroot
directory you have,
 then start a new test buildroot directory and use the correct FP config to
see if this will prevent the error below.

On 2/28/08, Nicola Salvemini <nicolasalvemini at yahoo.it> wrote:
>
> Yes,
> I tried to select option "Use software floating point by default" from
> buildroot configuration menu, but I have some compilation problems:
>
> /home/user/buildroot/build_arm/staging_dir/usr/arm-linux-uclibc/bin/ld:
> ERROR: libgcc/./_udivsi3_s.o uses hardware FP, whereas ./libgcc_s.so.1.tmp
> uses software FP
> /home/user/buildroot/build_arm/staging_dir/usr/arm-linux-uclibc/bin/ld:
> failed to merge target specific data of file libgcc/./_udivsi3_s.o
> /home/user/buildroot/build_arm/staging_dir/usr/arm-linux-uclibc/bin/ld:
> ERROR: libgcc/./_divsi3_s.o uses hardware FP, whereas ./libgcc_s.so.1.tmp
> uses software FP
> /home/user/buildroot/build_arm/staging_dir/usr/arm-linux-uclibc/bin/ld:
> failed to merge target specific data of file libgcc/./_divsi3_s.o
>
> ....
>
> etcetera...
>
> Best regards,
> Nicola.
>
>
> ----- Messaggio originale -----
> Da: Rex Ashbaugh <rexa at xeratech.com>
> A: Nicola Salvemini <nicolasalvemini at yahoo.it>
> Cc: buildroot at uclibc.org
> Inviato: Giovedì 28 febbraio 2008, 16:33:19
> Oggetto: Re: [Buildroot] Problem with iperf
>
> Also, check how your cross compiler is configured for floating point
> handling..
>
> http://www.arm.linux.org.uk/mailinglists/faq.php
>
> 3. I feel really confused about what's the difference with gcc
>
>           soft-float support and the kernel NWFPE/FastFPE support?
>           [31 January 2004 - np]
>           Scenario 1 (hard-float): The compiler emits opcodes designed to
>
>  be  used  with a hardware floating point coprocessor (FPU). The
>
>           FPU  usually  has a set of extra registers for its use, and the
>           compiler  may as well pass floating point argument to functions
>           through  those registers. This is of course the best performing
>
>           solution when a real hardware FPU is used.
>
>           Scenario  2  (soft-float): the compiler converts floating point
>           operations into function calls and a special library is used to
>           provide  all  functions performing the required operations, all
>
>           in software with no FPU instructions at all. There is obviously
>           no  extra  floating  point  registers  available  in this case,
>           therefore  all  FP  arguments  to  functions  have to be passed
>
>           through  standard  registers or on the stack. This is of course
>           the best performing solution when no
>  hardware FPU is available,
>           given  that  the  library  implementing  the  FP  operations is
>
>           optimally coded.
>
>           Now,  unfortunately, the default on ARM Linux has traditionally
>           been set to have the compiler use hard-float, even if ARM Linux
>           never  ran  on any ARM CPU with a real hardware FPU. The CPU is
>
>           therefore  raising  the invalid instruction exception each time
>           some  FPU  opcode  is  encountered.  Then the kernel traps that
>           exception,  looks  at the given FPU instruction and emulates it
>
>           in  software.  But here not only the kernel must perform the FP
>           operation,  it  must  emulates  the whole hardware FPU as well.
>           That's  what  NWFPE or FastFPE are doing. This is obviously the
>
>           worst  performing  arrangement that can be due to the exception
>           trap and emulation
>  overhead
>
>
>
> On 2/28/08, Nicola Salvemini <nicolasalvemini at yahoo.it> wrote:
> >
> > Hi Rex,
> >
> > Yes I tried with the previous version (2.0.1) of iperf, bat I had same
> > results.
> > I'm waiting for a replay from iperf maintainer.
> > Best regards,
> >
> > Nicola.
> >
> > ----- Messaggio originale -----
> > Da: Rex Ashbaugh <rexa at xeratech.com>
> > A: Nicola Salvemini <nicolasalvemini at yahoo.it>
> > Cc: buildroot at uclibc.org
> > Inviato: Mercoledì 27 febbraio 2008, 16:52:03
> > Oggetto: Re: [Buildroot] Problem with iperf
> >
> >
> > NWFPE is the floating point emulator.
> >
> > 00000002 is a floating point divide-by-zero.
> >
> > try another version of iperf maybe?
> > report this problem to the iperf maintainer?
> > -Rex
> >
> >
> > On 2/27/08, Nicola Salvemini <nicolasalvemini at yahoo.it> wrote:
> > >
> > > Hi all,
> > >
> > > I have a ARM arm926t (it's a little-endian) target platform and I use
> > > buildroot to cross-compile applications.
> > > I include iperf in the package selection for the target and the build
> > > phase go to the end without problems, but when I try to use iperf on the
> > > target, I take an exception:
> > >
> > > NWFPE: iperf[770] takes exception 00000002 at c00288f0 from 400f4580
> > > NWFPE: iperf[770] takes exception 00000002 at c00288f0 from 400f4580
> > > NWFPE: iperf[770] takes exception 00000002 at c00288f0 from 400f4580
> > >
> > > Could you please give me an idea to resolve the problem?
> > > Thanks in advance,
> > >
> > >
> > > Nicola.
> > >
> > >
> > >
> > >
> > >
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