Re: [dpdk-dev] [PATCH v4 0/2] eal: choose initial PRNG seed source at runtime

[Dan Gora <dg@adax.com>]

On Mon, Jun 29, 2020 at 3:01 PM Dan Gora <dg@adax.com> wrote:
>
> On Mon, Jun 29, 2020 at 6:32 AM Mattias Rönnblom
> <mattias.ronnblom@ericsson.com> wrote:
> >
> > On 2020-04-23 01:42, Dan Gora wrote:
> > > Hi All,
> > >
> > > The following patches updates the rte_random subsystem to dynamically find
> > > the best source of the initial seed to the PRNG at run time.
> > >
> > > The first patch enables dynamic checking for the rdseed instruction and
> > > removes the requirement for it on the execution system.  It also ensures
> > > that the code to use the rdseed instruction is generated, even if the host
> > > compilation system does not support it (on x86 systems).
> > >
> > > The second patch emulates the getentropy() glibc function by reading bytes
> > > from /dev/urandom.  This removes an unnecessary dependency on glibc 2.25.
> > >
> > > v4:  Note that emulating getentropy by reading from /dev/urandom should
> > > never fail, so now the question is if we should just remove the rdseed
> > > method entirely since it's x86 only?  Should we remove the fallback to
> > > rte_get_tsc_cycles()?
> > >
> > > Thanks
> > > Dan
> > >
> > > -----
> > > v2:
> > > * Fix patch apply issue.
> > > * dlclose() handle if dlsym() fails in __rte_getentropy().
> > >
> > > v3:
> > > * Fix error checking of dlsym() in __rte_getentropy().
> > > * Style changes recommended by Mattias.
> > >
> > > v4:
> > > * Replace dlopen/dlsym method with reading from /dev/urandom.
> > > * Try rdseed method before getentropy() method since the
> > >    latter should never fail.
> >
> >
> > I see no reason to prefer rdseed over the kernel.

It even says why right here:

> > > * Try rdseed method before getentropy() method since the
> > >    latter should never fail.

*******since the latter should never fail*******

Did  you see that part?

thanks
dan