linux-kernel - Re: [PATCH v2 1/1] x86/rdrand: disable RDSEED on AMD Cyan Skillfish

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Message-ID: <CAHSgyMNt_NV_PQoRZ1F+-GgE+jRwrCMXg91G96ppNnCXCw19cA@mail.gmail.com>
Date: Wed, 14 Jan 2026 16:41:29 -0500
From: Travis B <tbangs89@...il.com>
To: Borislav Petkov <bp@...en8.de>
Cc: me@...aill.net, dave.hansen@...ux.intel.com, linux-kernel@...r.kernel.org, 
	mario.limonciello@....com, mingo@...hat.com, tglx@...utronix.de, 
	x86@...nel.org
Subject: Re: [PATCH v2 1/1] x86/rdrand: disable RDSEED on AMD Cyan Skillfish

>It is still important, though, to make sure the user sees this and does not
use RDSEED for generating random data used in sensitive communication.

With RDSEED cpuid bit disabled by the code, a user should
use that to determine whether they should use the instruction
or not. It becomes the same as using any other CPU which
already does not support RDSEED, which do not get
a forced emergency system message for it.

pr_emerg is intended for fatal errors where the system cannot
operate anymore. That is way above the level of RDSEED
being disabled. There are no other places in kernel where disabling
support for an instruction generates an emerg level message.

>And they wanna disable it because?
Because they are only interested in seeing errors.