[yocto] TARGET_FPU not getting populated for powerpc 405/440 fpu-hard targets

Elvis Dowson elvis.dowson at gmail.com
Fri Aug 24 09:49:01 PDT 2012


Hi Khem,

On Aug 24, 2012, at 8:35 PM, Khem Raj wrote:

> On Fri, Aug 24, 2012 at 9:27 AM, Elvis Dowson <elvis.dowson at gmail.com> wrote:
>> I just observed that TARGET_FPU is not getting populated, when you do
>> a build for fpu-hard targets. For fpu-soft targets, it displays TARGET_FPU =
>> "soft", but for fpu-hard targets, it display TARGET_FPU = "".
> 
> that means default is hard for this architecture. This option is
> essentially used to configure gcc
> unless your fpu is special like fsl one's you are good here.

The FPU unit is an IP core, that is attached to a generic PowerPC405 or PowerPC440 embedded processor core on the FPGA, which by default doesn't contain an FPU unit. 

In the Xilinx FPGA hardware project, I have to add this FPU unit, and there are some additional options that I can see relevant to this setup with the FPU unit, such as -mxilinx-fpu and -mfpu=dp_full

Should I specify them in TUNE_CCARGS (as shown below) or TUNE_FEATURES_tune-ppc405e (not done below) or specify the same values for both variables ?

TUNE_CCARGS += "${@bb.utils.contains("TUNE_FEATURES", "ppc405e", "-mcpu=405fp -mxilinx-fpu -mfpu=dp_full", "", d)}"

AVAILTUNES += "ppc405e"
TUNE_FEATURES_tune-ppc405e = "m32 ppc405e fpu-hard"

Best regards,

Elvis Dowson
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