[Bug target/94087] std::random_device often fails when used from multiple threads

rguenther at suse dot de gcc-bugzilla@gcc.gnu.org
Thu May 14 11:38:24 GMT 2020


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94087

--- Comment #17 from rguenther at suse dot de <rguenther at suse dot de> ---
On Thu, 14 May 2020, redi at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94087
> 
> --- Comment #14 from Jonathan Wakely <redi at gcc dot gnu.org> ---
> (In reply to Jonathan Wakely from comment #13)
> > I'd rather not have to do everything shown at
> > https://software.intel.com/content/www/us/en/develop/articles/intel-digital-
> > random-number-generator-drng-software-implementation-guide.html to produce a
> 
> That was meant to link to section 5.2.6 "Generating Seeds from RDRAND"
> https://software.intel.com/content/www/us/en/develop/articles/intel-digital-random-number-generator-drng-software-implementation-guide.html#inpage-nav-5-7
> 
> > stronger seed from RDRAND.
> 
> Given that RDRAND is already an acceptable implementation for
> std::random_device, and the standard makes no guarantees about the
> cryptographic strength of values returned from std::random_device, using RDRAND
> directly is a reasonable alternative.

How about falling back to the mersenne twister?  Or does that invoke
too much overhead in the fallback case?  At least it is reliably
there and cannot fail.


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