[Development] Broken RNG on AMD Ryzen CPUs affect QTemporaryFile, Qt IFW

[Sze Howe Koh]

On Tue, 18 Feb 2020 at 20:57, Edward Welbourne <edward.welbourne at qt.io> wrote:
>
> On Tue, 18 Feb 2020 19:35:53 +0800
> Sze Howe Koh <szehowe.koh at gmail.com> wrote:
> >> See https://forum.qt.io/topic/111473/maintenance-tool-error-cannot-open-file-for-writing-no-error/
>
> I note that the code quoted is using rand(); the code in QTemporary file
> switched to using QRandomGenerator at 5.10.0; that's what now produces
> the "WARNING: RDRND generated:" message reported in one post.
>
> Christian Kandeler (18 February 2020 12:59) replied
> > Probably the same as https://bugreports.qt.io/browse/QTBUG-77375.
>
> Fixed in 5.13.0 - the fix added the warning quoted above and takes steps
> to ensure we don't rely on the broken HWRNG, presumably falling back to
> some pseudo-random alternative.
>
> >> Is this worth a post on the Qt Blog? I foresee many frustrated and
> >> confused Ryzen users out there who would benefit from a reminder to
> >> update their BIOS.
>
> > I suppose it won't hurt, but I wonder how such a system is usable at
> > all...
>
> Which version was this encountered in ?
>
>         Eddy.

Judging from the screenshots, it's the latest and greatest version of
the Qt installer (qt-opensource-windows-x86-5.14.1.exe) [1]

If it matters, I also realized the error message was actually:

    Cannot open file "" for writing: No error


Regards,
Sze-Howe

[1] https://forum.qt.io/post/578114