linux-kernel - Re: [PATCH 3/3] hwrng: Don't default to HW_RANDOM when UML

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Message-ID: <Z6hyK-nU_mLxw-TN@gondor.apana.org.au>
Date: Sun, 9 Feb 2025 17:15:23 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Dragan Simic <dsimic@...jaro.org>
Cc: linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
	olivia@...enic.com, didi.debian@...ow.org, heiko@...ech.de
Subject: Re: [PATCH 3/3] hwrng: Don't default to HW_RANDOM when UML_RANDOM is
 the trigger

On Wed, Jan 15, 2025 at 02:07:02PM +0100, Dragan Simic wrote:
> Since the commit 72d3e093afae (um: random: Register random as hwrng-core
> device), selecting the UML_RANDOM option may result in various HW_RANDOM_*
> options becoming selected as well, which doesn't make much sense for UML
> that obviously cannot use any of those HWRNG devices.
> 
> Let's have the HW_RANDOM_* options selected by default only when UML_RANDOM
> actually isn't already selected.  With that in place, selecting UML_RANDOM
> no longer "triggers" the selection of various HW_RANDOM_* options.
> 
> Fixes: 72d3e093afae (um: random: Register random as hwrng-core device)
> Reported-by: Diederik de Haas <didi.debian@...ow.org>
> Signed-off-by: Dragan Simic <dsimic@...jaro.org>
> ---
>  drivers/char/hw_random/Kconfig | 76 +++++++++++++++++-----------------
>  1 file changed, 38 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
> index e84c7f431840..283aba711af5 100644
> --- a/drivers/char/hw_random/Kconfig
> +++ b/drivers/char/hw_random/Kconfig
> @@ -38,47 +38,47 @@ config HW_RANDOM_TIMERIOMEM
>  config HW_RANDOM_INTEL
>  	tristate "Intel HW Random Number Generator support"
>  	depends on (X86 || COMPILE_TEST) && PCI
> -	default HW_RANDOM
> +	default HW_RANDOM if !UML_RANDOM

This is disgusting.  Just remove all the defaults, and we can
add back the ones actually needed.  Just remember to set the
default to something sane like HW_RANDOM && dependencies.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt