[Interest] Qt 5.15 LTS vs Qt 6.2 LTS

[Tuukka Turunen]

Hi Roland et al,

Certain industries have also defined approach to safety by separating the safety critical functionality from other functionality. Typically, in these the approach is such that the system needs to ensure the safety critical functionality to work with desired likelihood and the other functionality to not interfere with the safety critical functionality.

Qt is well suited for this type of an approach, and we also have a certified solution to the safety critical functionality: https://www.qt.io/product/functional-safety-and-qt

As a large framework Qt is not directly created for approach where it alone needs to provide a safety critical functionality without any support from the system architecture (noting that the Qt Safe Renderer is specifically created for this purpose). Anything is possible, but our recommendation is to approach the topic from system design viewpoint. Separating the safety critical functionality and creating a viable approach for it. If Qt libraries are used without such separation by the system, it requires extensive testing of the exact functionality used (both for Qt framework and the application).

It should be noted that while there are many similarities, multiple industries have also defined their own approach to functional safety. With Qt Safe Renderer we are directly addressing: IEC 61508, IEC 62304, ISO 26262 and EN 50128. Check details from the link above, if interested. Other ones can be also addressed leveraging the material created during the certification process, but requires additional steps.

While you are free to discuss the creation of safety critical systems via the Qt project mailing lists, in case you or someone are planning to create one, would be better to discuss with our functional safety experts and leverage items that are part of our commercial offering.

Yours,

                Tuukka



From: Interest <interest-bounces at qt-project.org> on behalf of Ulf Hermann <ulf.hermann at qt.io>
Date: Saturday, 2. October 2021 at 18.15
To: interest at qt-project.org <interest at qt-project.org>
Subject: Re: [Interest] Qt 5.15 LTS vs Qt 6.2 LTS
> There are no patient killing bugs in the underlying OS or the previously
> used drivers. Those only exist in the new drivers, new OS patches and
> new Qt code. All of the new code has to be written following 62304 SDLC

Although I doubt that Windows XP or the new graphics drivers are free of
patient killing bugs, I have to admit that you have a point here: If MS,
AMD, NVidia etc. went through the certification process with their
software, we can trust their software as much as we can trust anything
in such a system.

Now, what you probably want from Qt is a package that eliminates most of
those 5000+ bugs and that can itself be certified or at least accepted
in the approval process. The way to get there might be as follows:

1. Define a the feature set you need from Qt.
2. Turn off all unnecessary features using -no-feature-xyz on the
configure script (possibly defining more features in order to be able to
turn them off).
3. Wade through the bug database and sort out the bugs that remain valid
for such a stripped down Qt.
4. Deal with those bugs in whatever way the approval process mandates.
5. Port the resulting Qt to your target platform.

I might be wrong with those steps because I don't know the approval
process. Yet, I'm sure there is some pragmatic way to produce what you
want. You may want to share your ideas on what it actually takes.

While all of this is possible, it obviously is a lot of work. If you
want to do the work yourself, let's discuss the details here. If you
want to pay for such work to be done, you may want to get in contact
with the Qt Company. If you want to lament about such a specialized Qt
not materializing out of thin air, you got my sympathies, but you may
not get everybody's sympathies here. If you want to repeat that no one
you know is using Qt anymore, that won't be necessary. We've read it
often enough.

best regards,
Ulf
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