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https://bugzilla.redhat.com/show_bug.cgi?id=1679010

seeing this log:

Failed to init entropy source hwrng

Does Intel or AMD CPU contain a hwrng device? or it need extra chip/card/device?

Mark K
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1 Answers1

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No, a CPU typically does not contain a hwrng device. Instead, modern x86 CPUs with hardware RNG capabilities typically have a RDRAND instruction. It was introduced by Intel in the Ivy Bridge generation (in 2012) and AMD copied it in 2015.

A hwrng device is typically a feature of the system chipset, to provide a hardware RNG even if a processor that doesn't have the RDRAND instruction is installed, or of a security module or cryptographic accelerator card that provides a hardware RNG as an adjunct to their main functionality. There are also dedicated hardware RNG devices, like the LavaCan of the LavaRNG project.

Since RDRAND is now ubiquitous in modern x86 CPUs, the chipset designers might as well start omitting the hwrng device in new chipsets to simplify their designs.

telcoM
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  • so the message 'Failed to init entropy source hwrng' means there is no hwrng device? – Mark K Jul 15 '21 at 13:05
  • Either that, or if there was a hwrng device, then it did not work as expected. Is there a /dev/hwrng device node or not? – telcoM Jul 15 '21 at 13:32