[Buildroot] Qt5 puzzle

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Dear Charles Krinke,

On Wed, 6 Nov 2013 08:57:45 -0800, Charles Krinke wrote:

> Recently one of our app engineers moved to QtQuick 2.0 and all of a sudden
> with the buildroot built binaries from Qt-5.0.2, I am seeing this error
> when a qml-style program is run.
> 
> ERROR: Binary compiled with -mfloat-abi=hard but without
> -DUSE_EABI_HARDFLOAT
> 
> In searching this, I can see mention of this on the buildroot mailing list
> from June, but no hints or resolution. The archive of the mailing list is
> this page:
> 
> http://buildroot-busybox.2317881.n4.nabble.com/ERROR-Binary-compiled-with-mfloat-abi-hard-but-without-DUSE-EABI-HARDFLOAT-td49130.html
> 
> Although I am using the TI AM3517 and not Raspberry Pi, the error seems to
> be the same.
> 
> I am assuming this has something to do with make options. This morning, I
> tried adding "-DUSE-EABI_HARDFLAT" to the Makefile for libQt5V8 where the
> offending message is coming from, but the cheap shot doesnt work.
> 
> I am working with a buildroot from the end of July, so am not using the
> experimental Qt-5.1 stuff (yet) and am hoping not to move forward in a
> crisis if I can help it.
> 
> So, ... as usual, I am hoping for a clue or two to let me understand how to
> get QtQuick back to functionality with Qt-5.0.2.

Interesting. I had a look at this, in Qt 5.0.2, as packaged in
Buildroot 2013.08. Normally, the USE_EABI_HARDFLOAT flag should
automatically be set to 1 by Qt. From src/v8/v8.pri:

equals(V8_TARGET_ARCH, arm) {
DEFINES += V8_TARGET_ARCH_ARM
config_hardfloat {
    DEFINES += USE_EABI_HARDFLOAT=1
} else {
    DEFINES += USE_EABI_HARDFLOAT=0
}
...

config_hardfloat is I believe decided from the test executed from the
main qtjsbackend.pro:

qtCompileTest(hardfloat)

and there is indeed a config.tests/hardfloat/, which builds a program,
and then looks up with readelf if it's built hard float or not. Most
likely this test is failing, for some reason, and therefore believes
that the toolchain is not hardfp, while it actually is. I had a quick
read of the test and it seems to be testing something correct.

Can you post your .config so we can see what your toolchain is and what
is your Buildroot configuration?

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com