[meta-freescale] Yocto standard SDK machine dependent compiler options

[Zhenhua Luo]

Hi Matt,

The cross-build gcc is shared by different PPC architecture, including e500v2, e500mc, e5500 and e6500, those -m parameters are necessary for cross-compiling of specific core type. The following manual may be helpful to understand of Yocto SDK.

https://www.yoctoproject.org/docs/2.1/sdk-manual/sdk-manual.html


Best Regards,

Zhenhua

From: meta-freescale-bounces at yoctoproject.org <meta-freescale-bounces at yoctoproject.org> On Behalf Of Tsai, Matt
Sent: Friday, March 22, 2019 9:40 AM
To: meta-freescale at yoctoproject.org
Subject: [meta-freescale] Yocto standard SDK machine dependent compiler options

Hi all,

I have built the standard Yocto SDK using the "bitbake <image> -c populate_sdk" command. I have some questions related to the generated toolchain. I wonder if I can get my doubts cleared here.

Here are my hardware/software info:
Target platform is Freescale p2020 rdb.
Yocto versions used to build the SDK:
Poky: tag "sumo-19.0.1"
Meta-freescale: sumo branch commit hash: 407c6cf408969445031a492e2d25e0e2749582ea (on Oct. 4, 2018)

Questions:

  1.  The generated SDK contains a script environment-setup-ppce500v3-poky-linux-gnuspe to source some machine-dependent compiler options. I assume these are good (if not optimal) options to use when I build my applications. And the generated code is able to make use of two cores and other hardware features of the p2020 processor. Is this correct? What is the effect if I do not add these -m options?



I list some of the compiler/assembler options below:

CC="powerpc-poky-linux-gnuspe-gcc  -m32 -mcpu=8548 -mabi=spe -mspe -mfloat-gprs=double --sysroot=$SDKTARGETSYSROOT"

CXX="powerpc-poky-linux-gnuspe-g++  -m32 -mcpu=8548 -mabi=spe -mspe -mfloat-gprs=double --sysroot=$SDKTARGETSYSROOT"

CPP="powerpc-poky-linux-gnuspe-gcc -E  -m32 -mcpu=8548 -mabi=spe -mspe -mfloat-gprs=double --sysroot=$SDKTARGETSYSROOT"

AS="powerpc-poky-linux-gnuspe-as "

LD="powerpc-poky-linux-gnuspe-ld  --sysroot=$SDKTARGETSYSROOT"



  1.  If these -m options are not good to use, do I need to build the compilers with different configurations? Or add different machine dependent options?
  2.  Are there any documents/references of these machine-dependent options besides the -target-help from the command line?


If this not the right place for the questions, please kindly point me to the right source.

Thank you very much for the help!

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