Messages in this thread | | | From | Ard Biesheuvel <> | Date | Sun, 19 Apr 2020 10:55:00 +0200 | Subject | Re: Fw: Arm CryptoCell driver -- default Y, even on machines where it is obviously useless |
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On Sun, 19 Apr 2020 at 08:33, Gilad Ben-Yossef <gilad@benyossef.com> wrote: > > > > -----Original Message----- > > > From: Pavel Machek <pavel@ucw.cz> > > > Sent: Saturday, 18 April 2020 13:44 > > > To: kernel list <linux-kernel@vger.kernel.org>; Hadar Gat > > > <Hadar.Gat@arm.com>; herbert@gondor.apana.org.au > > > Subject: Arm CryptoCell driver -- default Y, even on machines where it is > > > obviously useless > > > > > > Hi! > > > > > > I'm configuring kernel for x86, and I get offered HW_RANDOM_CCTRNG with > > > default=Y, and help text suggesting I should enable it. > > > > > > That's... two wrong suggestions, right? > > > > > > Best regards, > > > Pavel > ... > > ________________________________________ > > From: Hadar Gat <Hadar.Gat@arm.com> > > Sent: Saturday, April 18, 2020 11:31 PM > > To: Pavel Machek; kernel list; herbert@gondor.apana.org.au > > Cc: Ofir Drang; Gilad Ben Yossef; nd > > Subject: RE: Arm CryptoCell driver -- default Y, even on machines where it is obviously useless > > > > Hi Pavel, > > I think you got it right.. > > Indeed, Arm CryptoCell CCTRNG driver couldn't be used and obviously useless if the Arm CryptoCell HW does not exist in the system. > > There's a delicate point here though - CryptoCell is an independent > hardware block, it is not tied to a particular CPU architecture. > There are SoCs with none-Arm architecture CPU using it. > > So I would say whatever the answer is, it should be the same for any > generic embedded style HW block. > > And the help text is not architecture specific anyway, is it not..? >
Both the default y and and the help text are indeed incorrect. This should be fixed. We don't enable device drivers by default, and definitely not as as builtins. A conditional default m could be acceptable if the condition is sufficiently narrow.
While at it, could we add a depends on CONFIG_OF since this code is definitely unusable on non-DT systems.
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