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Re:

To: Jabir M <Jabir_M@pmc-sierra.com>
Subject: Re:
From: Manuel Lauss <manuel.lauss@googlemail.com>
Date: Fri, 11 Jun 2010 16:32:00 +0200
Cc: linux-mips@linux-mips.org, ralf@linux-mips.org
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Sender: linux-mips-bounce@linux-mips.org
Hi,

On Fri, Jun 11, 2010 at 4:06 PM, Jabir M <Jabir_M@pmc-sierra.com> wrote:
>    I am working on a FPU-less 34k MIPS platform with linux-2.6.24
> kernel. After running a Darwin media streaming server on the board
> for a while, my oprofile results shows high utilization on
> fpu_emulator_cop1Handler() & r4k_wait().
>
> wiki page http://www.linux-mips.org/wiki/Floating_point says gcc will
> use hard float as default and soft float is best suited model for a
> fpu less processor.  Could anyone kindly help me in understanding use
> of -msoft-float .
> Whether I need to compile
>
> 1. kernel with -msoft-float ? or
> 2. Glibc ? or
> 3. Application ? or
> 4. All the above ?

I have fought with this in the past; what you need to do is:
- build gcc with softfloat support (mipsel-softfloat-linux-gnu triplet
for example),
- build a libc with this new compiler,
- then rebuild all libraries and apps with you new softfloat toolchain.

<plug>
I have a working softfloat environment for MIPS32 here at [1], it includes a
complete c/c++ toolchain with gcc-4.4.3.   It's built for mips32r1, no idea if
it is supposed to work with 34k cores.
</plug>

Best regards,
        Manuel Lauss

[1]  http://mlau.at/files/mips32-linux/

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