On 18/09/2017 7:59 pm, "Christian Gagneraud" <chg...@gmail.com
<mailto:chg...@gmail.com>> wrote:
On 18/09/2017 7:34 pm, "Sami Nurmenniemi" <sami.nurmenni...@qt.io
<mailto:sami.nurmenni...@qt.io>> wrote:
On 15.09.2017 18:21, Thiago Macieira wrote:
On Friday, 15 September 2017 00:31:36 PDT Sami Nurmenniemi
wrote:
I think we'll just have to accept blocking for the
devices without
hwrng. I don't know if we really support any such
devices. If we do and
boot time is essential for those, we'll have to figure
out some way
(probably saving entropy over reboot).
And that would be a non-Qt job. I wasn't worried about Qt
on real devices
because I don't expect it to be run early enough to
matter. On VMs, that's
another story, and if you don't trust your
undercloud-provided /dev/hwrng, why
are you using that cloud? (Though I'll say there's an
Intel team working on
figuring out how a VM can get trust from the actual
hardware, skipping the
hypervisor trust)
We have made some safety critical customer demos where fast
boot time of Qt framework is essential. It was demoing boot
time of 1.2s for a Qt application to start after powering on
the device. I suppose that demo (and real safety critical use
cases) is going to have problems with the QRandomGenerator
even with hwrng in use.
So basically, you have artificially "optimised" boot time by
ignoring entropy management and now you're blaming
QRandomGenerator. You can do one or the other, not both.
Me too I can make a device boot in less than a second, but then
don't be surprised if some features are missing/buggy....
This sound very much like a beginner mistake, where boot time
takes over functionality. Every one can boot an unfunctional
device in less than a second. This is nothing new.
The point of mentioning the 1.2s demo was an answer to the statement "I
wasn't worried about Qt on real devices because I don't expect it to be
run early enough to matter." Maybe the demo application (being the only
user space process) needs to make the connection between hwrng + random
pool or preserve entropy over reboots.
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