u-boot 2020.04-5.10.9 build with floating point operation

[TKayO]

Hello, it's my first time in Yocto and NXP product. 

So please understand some part of my question is weird.

I'm trying to do port the code from (A)u-boot 2009 to (B)u-boot 2020.

(A) contains some double, float operation, it's about OLED setting.

(A) compiles with no problem, toolchain is "gcc-4.6.2-glibc-2.13-linaro-multilib-2011.12"

I copied these OLED setting code to my (B)u-boot 2020.

There happened build errors from several reasons.

1) when libgcc is not linked, "undefined reference to `__aeabi_d2iz'" occurred.

2) after libgcc provided, -msoft-float option conflicted with 

    arm-poky-linux-gnueabi- tool chain's libgcc.a, it supports only hardfp(?.. I'm not sure)

So I changed config.mk and some defconfigs like below

https://community.nxp.com/t5/i-MX-Processors/bitbake-u-boot-imx-failed-because-undefined-reference-t...

now I can build without error

but when it's executed "undefined instruction" error shown and stopped.

This is my recent three days work.

And my question is. 

1) Can I modify my given (yocto provided) toolchain ARM-POKY-LINUX-GNUEABI-  to support softfp enabled libgcc.a?

2) If 1) is not possible, can I build (B)u-boot 2020 with "gcc-4.6.2-glibc-2.13-linaro-multilib-2011.12" toolchain?

3) Any opinions why "undefined instruction" happens?

If any of above answers are "YES" then please let me know how.. 

Regards.

[TKayO · Accepted solution]

I modified source/meta-freescale/conf/machine/include/imx-base.inc

DEFAULTTUNE_mx6 ?= "cortexa9thf-neon" --> "cortexa9t-neon"

and rebuilt toolchain and got softfp toolchain and libgcc.

u-boot built with no error and runs well. 

Am I doing right?