Re: systemctl restart sddm
On Wednesday, August 1, 2018 7:01:42 PM CEST you wrote:
> On Wednesday, August 1, 2018 6:10:56 PM CEST you wrote:
> > Looking at: [1](https://wiki.archlinux.org/index.php/Rng-tools), and then
> > following to: [2](https://en.wikipedia.org/wiki/
> > Hardware_random_number_generator), one can think that rng-tools uses: [3]
> > (https://en.wikipedia.org/wiki/RdRand).
> >
> > But it might not be so, since [2] says: "The RdRand opcode will return
> > values from an onboard hardware random number generator. It is present in
> > Intel Ivy Bridge processors and AMD64 processors since 2015", and
> > IvyBridge
> > started in 2012, and rng-tools code is very, very old (but there is some
> > overlapping time, possibly).
> >
> > Therefore believing that rng-tools uses RdRand's CPU hardware random
> > generator instruction, might be pure misconception.
> >
> > Consequently, haveged seeming much newer and maintained, it is in my
> > opinion the best choice.
>
> It seems the overlapping time was sufficient to "Add RDRAND support" to
> rng-tools: (debian's rng-tools5)
>
> [4](https://git.kernel.org/pub/scm/utils/kernel/rng-tools/rng-tools.git/log/
> ?qt=grep&q=rdrand)
>
> "Add RDRAND support" (2012-07-31)
> [5](https://git.kernel.org/pub/scm/utils/kernel/rng-tools/rng-tools.git/comm
> it/?id=2a01453686f065ac95916fe49a02407914e05dd4)
>
> Next, is the redhat version:
> [6](https://github.com/nhorman/rng-tools/search?q=rdrand&unscoped_q=rdrand)
>
> debian's "rng-tools" (unofficial), seems to be to old, viz. anterior to
> 2012's IvyBridge, to use RdRand instruction:
> [7](https://tracker.debian.org/pkg/rng-tools)
> (last news, as of today, is from 2011-11-10)
>
My CPU is i5-3210m, which seems to be Ivy Bridge, and therefore it should
implement the RdRand instruction... rng-tools started before the introduction
of that instruction; So even though support for that instruction seems to have
been introduced in 2012, we should not take for granted that the hardware
generated random number from rng-tools, necessarily comes from that
instruction.
https://github.com/nhorman/rng-tools:
"The rng-tools official repository (formerly part of the gkernel project on
sourceforge)"...
So what is this version:
https://git.kernel.org/pub/scm/utils/kernel/rng-tools/rng-tools.git/
Which is the one used by debian, and pointed to by archlinux wiki, https://
wiki.archlinux.org/index.php/Rng-tools, and which seems to be several years
older than the nhorman/rng-tools's version?
Anyway, to be thorough, i removed haveged, and install rng-tools5 package, and
rebooted:
The reboot took the same time, to the second, as with haveged (counting in my
head).
(To be really thorough, I should remove also rng-tools5 and reboot, maybe the
sddm start delay has just vanished into thin air during the while; But that I
won't do now.)
So, I'll stick to it, because, well, why not.
Note: if it is for but one cpu's instruction, maybe that code could be
integrated in the kernel? (I've not found if IBM z13 processor integrate
RdRand instruction).
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