Re: building qt4 for arm

On Tue, 12 Feb 2013 16:28:17 +0100
Rieker Flaik <[email protected]> wrote:

> I'm running debian arm

There is no Debian ARM port anymore, it's either armel or armhf.

> and need to rebuild libqt4 with an additional
> patch. 

For armel, it is unlikely that you want the Debian package unless you
have a full Xorg server on your armel board.

You probably need a custom build of QtEmbedded which needs additional patches.

http://www.linux.codehelp.co.uk/serendipity/index.php?/archives/223-Qt-embedded-armel-for-Emdebian.html

http://www.emdebian.org/trac/browser/current/emdebian/trunk/qt4-embedded/tags

You'll need this version of the package instead of what is in Debian
even if you are going to be building natively, unless you have a FULL
Xorg installation on your board.

> What is the best and fastest way to rebuild that package?

Cross build - and don't use ever aptitude for cross-building or
multiarch, it's broken. 

>    aptitude install emdebian-archive-keyring
>    echo "deb http://www.emdebian.org/debian/ squeeze main" >> /etc/apt/sources.list
>    aptitude update
>    aptitude install gcc-4.4-arm-linux-gnueabi cpp-4.4-arm-linux-gnueabi

Wrong - you need g++-4.4-arm-linux-gnueabi as Qt is C++

Installing g++ brings in gcc and cpp as dependencies plus the rest of
the stuff needed for C++.

apt-get install g++-4.4-arm-linux-gnueabi
 
> Then I did:
>    apt-get source libqt4-dev
>    dpkg-buildpackage -aarmel -j4

Drop the -j4.

Install the cross-dependencies using embuilddeps:

apt-get install xapt
apt-get source libqt4-dev
cd qt4-....
sudo embuilddeps -m -a armel
dpkg-buildpackage -aarmel -d

dpkg cannot check cross-dependencies, so you need -d to skip that check.

> 
> The build-process started but died after 3 minutes with messages like
> this:
> 
>    animation/qsequentialanimationgroup.cpp:467: warning: unused variable ‘q’
>    ../../include/QtCore/../../src/corelib/arch/qatomic_arm.h: Assembler messages:
>    ../../include/QtCore/../../src/corelib/arch/qatomic_arm.h:131: Error: no such instruction: `swpb %al,%bpl,[%rbx]'
>    ../../include/QtCore/../../src/corelib/arch/qatomic_arm.h:131: Error: no such instruction: `swpb %al,%bpl,[%rbx]'

Due to lack of cross-dependencies, the wrong headers got included. That
resulted in x86 assembly being included into the armel cross build, not
surprisingly, that doesn't work.

It is probably best to ensure that libqt4-dev is not installed for your
build architecture (the build arch == the Big machine or the Desktop
machine - the host arch is the handheld architecture).

You don't want libqt4-dev itself when building Qt.

> I'm still searching for a practicable way of rebuilding bigger debian
> packages.
> 
> How do you do that?
> Any hints?

It will take many hours. Easily 5+. There again, building natively on a
Debian armel buildd box takes over 16hours.

-- 


Neil Williams
=============
http://www.linux.codehelp.co.uk/

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