Re: [PATCH 15/18] random: remove RDSEED fallback for initial seed

[Bruce Richardson]

On Tue, Sep 15, 2026 at 12:21:13PM -0700, Stephen Hemminger wrote:
> RDSEED is an x86 instruction that returns random bits from a hardware
> source. It has well known reliability problems: it can fail
> persistently when many cores use it at once, and several processors
> have errata affecting it. Since commit bfb3c5b9ffe7 ("random: always
> use getentropy") it was only reachable if getentropy() failed, which
> does not happen in practice.
> 
> Nothing is lost by removing it. The kernel already mixes RDSEED into
> its own entropy pool as one of several sources, so what it provides is
> present in the getentropy() result anyway, combined with other sources
> rather than trusted on its own.
> 
> The remaining fallback, the timestamp counter, still logs an error so
> that a low entropy seed is reported.
> 
> Signed-off-by: Stephen Hemminger <step...@networkplumber.org>
> ---
Acked-by: Bruce Richardson <bruce.richard...@intel.com>