Configuring Qmake mkspecs after it's built

[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

[wysota]

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

Forget apt-get, download QtCreator from here: http://www.qt.io/download-open-source/#section-6

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.

You can use schroot or a similar tool to have a Ubuntu 12.x installation inside your Ubuntu 14.x system.

Will qtcreator 3.x work on Ubuntu 12?

Yes.

Can I get binaries using apt-get from somewhere, or would I have to build it?

The link I gave you contains downloads for a binary release of QtCreator.

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.

You are confusing two things. Creator is just a tool, it has nothing to do with version of Qt you use to write your projects with. Creator is built against Qt5 but it can work with both Qt4 and Qt5 projects. Just use the download link I gave you and all will be fine.

[davethomaspilot]

You can use schroot or a similar tool to have a Ubuntu 12.x installation inside your Ubuntu 14.x system.

I'm actually running a Vmware player on windows 7. Are you suggesting running Ubuntu 12 inside 14.x in a Vm session on windows? Why, is the latest qtcreator incompatible with Ubuntu 12?

I understand QtCreator versus Qt libraries. But, I think I can do a lot of "GUI only" work on the Ubuntu host platform using Qt Designer and Qt4 stuff that will be compatible with what's available (without building qt) on the RPI. So, moving up to Qt5 on the host Ubuntu system would seem to only complicate things. Or, would it be easy to use a QtCreator built for Qt5, have the libraries it needs for running, but build local and target applications using Qt4? Whew....

I started the Wizard, but I need to know what it's going to do before I run it. It looks like I choose a Qt5 version to install.

I don't want to clobber the qt4 stuff until I understand the above issues better. Are you saying I can configure QtCreator built from Qt5 to use Qt4 for applications it builds?

Thanks!

[wysota]

I'm actually running a Vmware player on windows 7. Are you suggesting running Ubuntu 12 inside 14.x in a Vm session on windows? Why, is the latest qtcreator incompatible with Ubuntu 12?

No, you said you couldn't upgrade to newer kubuntu because of some missing library. I showed you how to do it - have a minimalistic Ubuntu 12 as a chroot in Ubuntu 14.

I understand QtCreator versus Qt libraries. But, I think I can do a lot of "GUI only" work on the Ubuntu host platform using Qt Designer and Qt4 stuff that will be compatible with what's available (without building qt) on the RPI. So, moving up to Qt5 on the host Ubuntu system would seem to only complicate things. Or, would it be easy to use a QtCreator built for Qt5, have the libraries it needs for running, but build local and target applications using Qt4? Whew....

Qt4 and Qt5 can live side by side. Qt Creator that I gave you a link to contains a bundled Qt5 environment so you don't have to build anything.

I don't want to clobber the qt4 stuff until I understand the above issues better. Are you saying I can configure QtCreator built from Qt5 to use Qt4 for applications it builds?

Just install the thing and stop worrying. I have a single instance of Creator working fine with Qt4 as well as Qt5, both native and cross-compiled. Creator is not tied to developing with any particular version of Qt. It just needs a particular version of Qt to run. And the binary release comes with one integrated which is totally separate from what you have in your system.