Is "Qt for device creation" a requirement for embedded development with Qt?

Damalo_02 · 18 Jun 2019, 12:10

Hello,

I was wondering if is it possible to develop on embedded systems without using "Qt for device creation"?
If yes, what is "Qt for device creation" for? Simplify development for embedded systems?

Thanks

sierdzio · 18 Jun 2019, 19:37

@Damalo_02 said in Is "Qt for device creation" a requirement for embedded development with Qt?:

I was wondering if is it possible to develop on embedded systems without using "Qt for device creation"?

Yes it is possible, with all licensing options (although satisfying GPL or LGPL requirements in an embedded system is quite a challenge).

If yes, what is "Qt for device creation" for? Simplify development for embedded systems?

Yep, exactly. It comes with some helping technologies (like boot2qt) and support from Qt Company to make development and deployment on embedded systems easier.

Damalo_02 · wrote on 18 Jun 2019, 15:28

Okay perfect, thanks a lot for your answer :)

rrd0 · 18 Jun 2019, 19:45

@sierdzio said

Yes it is possible, with all licensing options (although satisfying GPL or LGPL requirements in an embedded system is quite a challenge).

You made me curious. Could you list those challenges?

aha_1980 · R rrd0 18 Jun 2019, 19:37

@rrd0 the end-user must be able to replace the (L)GPL libs with other versions.

On an embedded device that means access (e.g. ssh), write possibilities to flash memory, a cross toolchain, you name it.

Much harder than on desktop systems, indeed.

Regards

jsulm · 19 Jun 2019, 05:35

@rrd0 To add to @aha_1980 : you have to provide build artefacts like object files (*.o) to the users, so they can relink the app with their own Qt libs. This is for LGPL.

GPL would force you to provide your source code to everyone asking for it.

sierdzio · wrote on 19 Jun 2019, 05:28

GPL would force you to provide your source code to everyone asking for it.

Where 'everyone' means every customer. People not using the software are not bound by it's license. So if OP wants to sell this product, they can provide full source code etc. only to paying customers. These customers, however, are free to distribute it further at any (or no) charge.

@aha_1980 @jsulm mentioned the most important (and hardest) points. Further requirements are:

LGPL:

include information in your application that Qt is used, under LGPL
include same info in documentation
include LGPL text
if you have made any major modifications to Qt itself, you need to release the source code of these modifications (not your app - only patches which modified Qt) to your clients asking for it
provide full Qt source code used to build the project - on demand - in practice most people just use Qt archive for that but technically the license requires you to store a copy on your side

J.Hilk · J jsulm 19 Jun 2019, 05:14

@jsulm said in Is "Qt for device creation" a requirement for embedded development with Qt?:

GPL would force you to provide your source code to everyone asking for it.

that's not strictly true.

I worked together with a router company for a time that was sued for GPL violations. The reason, they only released the source code when asked for it. Since the lawsuit they have to ship a cd/thumb-drive with each sold router...

sierdzio · wrote on 19 Jun 2019, 05:50

Interesting, good to know.