From: Hadar Gat <Hadar.Gat@arm.com>
To: Ard Biesheuvel <ardb@kernel.org>, Gilad Ben-Yossef <gilad@benyossef.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
kernel list <linux-kernel@vger.kernel.org>,
Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
nd <nd@arm.com>
Subject: RE: Fw: Arm CryptoCell driver -- default Y, even on machines where it is obviously useless
Date: Sun, 26 Apr 2020 12:49:57 +0000 [thread overview]
Message-ID: <DB6PR0802MB25337F768E6B2DCF943AC11CE9AE0@DB6PR0802MB2533.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <CAMj1kXEGSAD2Kkjg56UhMGgjuLBSOAKJ7ZMHdzfP2szGncu-4Q@mail.gmail.com>
Hi Ard,
> -----Original Message-----
> From: Ard Biesheuvel <ardb@kernel.org>
> Sent: Sunday, 19 April 2020 11:55
>
> > > > -----Original Message-----
> > > > From: Pavel Machek <pavel@ucw.cz>
> > > > Sent: Saturday, 18 April 2020 13:44
> > > >
> > > > 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
> > >
> > > 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.
On one hand I totally agree with that and think the default should be N.
On the other hand, most of the HW_RANDOM drivers set the default to HW_RANDOM
and it doesn't make sense to me to do something different than almost every other HW RANDOM device.
Do I miss something here?
>
> While at it, could we add a depends on CONFIG_OF since this code is
> definitely unusable on non-DT systems.
next prev parent reply other threads:[~2020-04-26 12:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200418104343.GA5132@amd>
[not found] ` <DB6PR0802MB2533670AFC1473E5C5EDAD28E9D60@DB6PR0802MB2533.eurprd08.prod.outlook.com>
[not found] ` <VI1PR08MB3584451F0B0B21E00ACF56A7FED70@VI1PR08MB3584.eurprd08.prod.outlook.com>
2020-04-19 6:33 ` Fw: Arm CryptoCell driver -- default Y, even on machines where it is obviously useless Gilad Ben-Yossef
2020-04-19 8:55 ` Ard Biesheuvel
2020-04-26 12:49 ` Hadar Gat [this message]
2020-04-26 12:56 ` Ard Biesheuvel
2020-04-26 13:06 ` Hadar Gat
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