Configuring Qmake mkspecs after it's built

[davethomaspilot]

I don't know if it's really even possible (see related thread on this forum that had no replies), but the 4.8 documentation says that an environment variable "QMAKESPEC" can be set to specify mkspecs:

The QMAKESPEC environment variable can contain any of the following:
A complete path to a directory containing a qmake.conf file. In this case qmake will open the qmake.conf file from within that directory. If the file does not exist, qmake will exit with an error.

However, while qmake does not exist with an error, setting the QMAKESPEC environment doesn't seem to have any effect:

davethomaspilot@ubuntu:/usr/share/qt4/mkspecs/linux-arm-g++$ echo $QMAKESPEC
/usr/share/qt4/mkspecs/linux-arm-g++
davethomaspilot@ubuntu:/usr/share/qt4/mkspecs/linux-arm-g++$ ls $QMAKESPEC
qmake.conf  qplatformdefs.h
davethomaspilot@ubuntu:/usr/share/qt4/mkspecs/linux-arm-g++$ qmake -query
QT_INSTALL_PREFIX:/usr
QT_INSTALL_DATA:/usr/share/qt4
QT_INSTALL_DOCS:/usr/share/qt4/doc
QT_INSTALL_HEADERS:/usr/include/qt4
QT_INSTALL_LIBS:/usr/lib/x86_64-linux-gnu
QT_INSTALL_BINS:/usr/bin
QT_INSTALL_PLUGINS:/usr/lib/x86_64-linux-gnu/qt4/plugins
QT_INSTALL_IMPORTS:/usr/lib/qt4/imports
QT_INSTALL_TRANSLATIONS:/usr/share/qt4/translations
QT_INSTALL_CONFIGURATION:/etc/xdg
QT_INSTALL_EXAMPLES:/usr/lib/qt4/examples
QT_INSTALL_DEMOS:/usr/lib/qt4/demos
QMAKE_MKSPECS:/usr/share/qt4/mkspecs
QMAKE_VERSION:2.01a
QT_VERSION:4.8.1

davethomaspilot@ubuntu:/usr/share/qt4/mkspecs/linux-arm-g++$ echo $QMAKESPEC
/usr/share/qt4/mkspecs/linux-arm-g++
davethomaspilot@ubuntu:/usr/share/qt4/mkspecs/linux-arm-g++$ ls $QMAKESPEC
qmake.conf  qplatformdefs.h
davethomaspilot@ubuntu:/usr/share/qt4/mkspecs/linux-arm-g++$ qmake -query
QT_INSTALL_PREFIX:/usr
QT_INSTALL_DATA:/usr/share/qt4
QT_INSTALL_DOCS:/usr/share/qt4/doc
QT_INSTALL_HEADERS:/usr/include/qt4
QT_INSTALL_LIBS:/usr/lib/x86_64-linux-gnu
QT_INSTALL_BINS:/usr/bin
QT_INSTALL_PLUGINS:/usr/lib/x86_64-linux-gnu/qt4/plugins
QT_INSTALL_IMPORTS:/usr/lib/qt4/imports
QT_INSTALL_TRANSLATIONS:/usr/share/qt4/translations
QT_INSTALL_CONFIGURATION:/etc/xdg
QT_INSTALL_EXAMPLES:/usr/lib/qt4/examples
QT_INSTALL_DEMOS:/usr/lib/qt4/demos
QMAKE_MKSPECS:/usr/share/qt4/mkspecs
QMAKE_VERSION:2.01a
QT_VERSION:4.8.1

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Here's what's in the qmake.conf in the directory specified by the QMAKESPEC env variable:

#
# qmake configuration for linux-g++
#

MAKEFILE_GENERATOR = UNIX
TARGET_PLATFORM = unix
TEMPLATE = app
CONFIG += qt warn_on release incremental link_prl gdb_dwarf_index
QT += core gui
QMAKE_INCREMENTAL_STYLE = sublib

include(../common/linux.conf)
include(../common/gcc-base-unix.conf)
include(../common/g++-unix.conf)
QMAKE_CC = $CROSS_COMPILE-gcc
QMAKE_CXX = $CROSS_COMPILE-g++
QMAKE_LINK = $CROSS_COMPILE-g++
QMAKE_LINK_SHLIB = $CROSS_COMPILE-g++
QMAKE_AR = $CROSS_COMPILE-ar cr
QMAKE_OBJCOPY = $CROSS_COMPILE-objcopy
QMAKE_STRIP = $CROSS_COMPILE-strip
QMAKE_LFLAGS_RELEASE = -Wl,-O1,-rpath $ROOTFS/usr/lib
QMAKE_INCDIR = $ROOTFS/usr/include
QMAKE_LIBDIR = $ROOTFS/usr/lib
QMAKE_INCDIR_X11 = $ROOTFS/usr/include
QMAKE_LIBDIR_X11 = $ROOTFS/usr/lib
QMAKE_INCDIR_OPENGL = $ROOTFS/usr/include
QMAKE_LIBDIR_OPENGL = $ROOTFS/usr/lib

load(qt_config)
davethomaspilot@ubuntu:/usr/share/qt4/mkspecs/linux-arm-g++$

Can qmake be configured to use different mkspecs after being built?

[wysota]

Why do you say it didn't work?

[davethomaspilot]

Why do you say it didn't work?

1) Note the value of the qmake variable QMAKE_MKSPECS
QMAKE_MKSPECS:/usr/share/qt4/mkspecs
2) Changing the value of the $QMAKESPEC env variable to a non-existant location doesn't cause any error when running qmake.
3) I get invalid qt version message in QtCreator when using qmake and trying to set a cross compile tool chain, regardless of whether $QMAKESPEC is set. It configures ok for local build which uses the qmake's qmakespec as configured for build

Is it possible to do what I'm trying to do and I'm just missing something?

Thanks,

Dave Thomas

[wysota]

1) Note the value of the qmake variable QMAKE_MKSPECS
QMAKE_MKSPECS:/usr/share/qt4/mkspecs
2) Changing the value of the $QMAKESPEC env variable to a non-existant location doesn't cause any error when running qmake.
3) I get invalid qt version message in QtCreator when using qmake and trying to set a cross compile tool chain, regardless of whether $QMAKESPEC is set. It configures ok for local build which uses the qmake's qmakespec as configured for build

Is it possible to do what I'm trying to do and I'm just missing something?

For me it works:

!build_pass {
    linux-*:message(LINUX)
    win32-*:message(WINDOWS)
}

!build_pass {
    linux-*:message(LINUX)
    win32-*:message(WINDOWS)
}

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QMAKESPEC=/home/wysota/Qt/5.3/gcc_64/mkspecs/win32-g++ qmake

yields:
Project MESSAGE: WINDOWS

Changing the specs will not modify the value of qmake variables, why would it? You are still within the same qmake installation.

Also remember you can always pass a different specs to qmake using the -spec parameter:

qmake -spec windows-g++

[davethomaspilot]

Thanks for the reply. It helps a lot to know it SHOULD work.

Maybe it's just QtCreator configuration issues. When I went back to native build on Raspberry Pi using QtCreator I kept getting messages about invalid Qt version when I tried going back to the native qmake. Turns out the real problem was that the build output directory was still pointing to the directory I was going to use on the ubuntu compiling machine--which doesn't exist from the RPI's point of view.

So, given this bad error message, I suspect several errors cause the same "invalid qt version" error. I think what's really happening is that the qmake selection doesn't change when other errors occur, so if it was invalid, it stays invalid until the other issues are fixed.

At least that's the path I'm going down next. I'll try get qmake working (creating makefiles with cross-compile toolchain) outside QtCreator, then use QtCreator using the -spec parameter if needed (I think I saw a thread indicating that may be required for cross-compiling).

Does remote debugging work from QtCreator 4.8 on Ubuntu with rpi as target? Haven't tried yet, but if it doesn't I'm less enthused about going to cross-compilation development.

I suspected the QMAKE_MKSPECS only indicated what was configured at build time, but there's nothing in the documentation (that I could find) that clarifies this.

Thanks!

[wysota]

Does remote debugging work from QtCreator 4.8 on Ubuntu with rpi as target?

Qt Creator's current version is 3.3 so I can't say whether it will work in 4.8

Haven't tried yet, but if it doesn't I'm less enthused about going to cross-compilation development.

I don't see why it shouldn't if you have gdbserver for Pi available.

[davethomaspilot]

So, I got it working using the -spec option like Wysota suggested.

Thanks!

---

Added after 1 27 minutes:

I don't see why it shouldn't if you have gdbserver for Pi available.

Yes, it works fine using the RPI gdbserver if I manuall start the gdbserver on the RPI and specify the debuggee (target) executable name.

It would be nice if QtCreator would launch gdbserver on the remote machine, but I don't see how to do that in the docs. I tried using Debug->Start Debugging->Start and Debug Remote Application, but that didn't work. Does QtCreator support this -- automatic launching gdbserver and the target app on the remote machine?

[wysota]

It would be nice if QtCreator would launch gdbserver on the remote machine, but I don't see how to do that in the docs.

Debug -> Start Debugging -> Start Remote Debug Server Attached to Process...

[davethomaspilot]

Debug -> Start Debugging -> Start Remote Debug Server Attached to Process..

That action isn't there in QtCreator 2.4.1. Under Debugging->Start Debugging, the remote debugging actions are:

• Start Remote Debug Server
• Attach to Remote Debug Server
• Start and Debug Remote application

"Start Debug Server" seems to be presenting a list of running processes on the target. That seems more like something that should be labelled "attach to process on remote machine", but I haven't tried this action.

"Attach to Remote Debug server" works, but only if I first launch the application under gdbserver first on the target platform. That's what I'm doing now.

"Start and Debug Remote application" sounds like the action I want, but when I try it, I get the message "Debugging has finished" in the application output window. The remote application never started.

Do I need to set up a start script on the host that gets executed on the target to launch gdbserver?

I'm just trying to get as tight a compile-test-debug-edit-compile cycle as possible. Now it's really quick compared to native RPI development. so while having to switch context to ssh, vnc, or target console to launch gdbserver is not a big deal, if support for automatic launch of a remote target process (and gdbserver) is in QtCreator there I want to use it.

[wysota]

That action isn't there in QtCreator 2.4.1.

That's a really ancient version. Why don't you upgrade to 3.x?

[davethomaspilot]

I'm using Ubuntu 12. 2.4.1 is the latest qtcreator available for it, according to apt-get.

I started with a new version of Ubuntu, but the ia32-lib that's required for cross-compiling to a raspberry pi target isn't available for the newer Ubuntu releases. I spent a lot of time trying work-arounds with no success and got nothing but silence when I asked on various forums if anyone had a solution that didn't require a 12.x Ubuntu host.

Will qtcreator 3.x work on Ubuntu 12? Can I get binaries using apt-get from somewhere, or would I have to build it? If I have to build it, can I use the qt4.8 binaries on that system? if I have to move up to qt5.x, then I have another pile o stuff to do to get qt5 up and going on the rpi.

Thanks,

Dave Thomas