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Date:   Sun, 04 Oct 2020 15:05:14 -0700 (PDT)
Subject:     Re: [PATCH] crypto: jitterentropy - bind statically into kernel
In-Reply-To: <CAMj1kXEnOh4MBiVVgkhd4P81eRPCVi3+y6JcD58jL45-eh324A@mail.gmail.com>
CC:     smueller@chronox.de, Christoph Hellwig <hch@infradead.org>,
        linux-riscv@lists.infradead.org, kernel-team@android.com,
        lkp@intel.com, linux-crypto@vger.kernel.org,
        linux-kernel@vger.kernel.org
From:   Palmer Dabbelt <palmerdabbelt@google.com>
To:     ardb@kernel.org
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On Sun, 04 Oct 2020 14:16:10 PDT (-0700), ardb@kernel.org wrote:
> On Sun, 4 Oct 2020 at 20:48, Stephan Müller <smueller@chronox.de> wrote:
>>
>> The RISC-V architecture is about to implement the callback
>> random_get_entropy with a function that is not exported to modules.
>
> Why is that? Wouldn't it be better to export the symbol instead?

It's static inline (in our timex.h), so I thought we didn't need to export the
symbol?  Did this just arise because clint_time_val wasn't exported?  That was
fixed before the random_get_entropy() change landed in Linus' tree, so as far
as I know we should be OK here.

If I broke something here it seem better to fix this in the RISC-V port than by
just banning modular compilation of jitterentropy, as that seems like a useful
feature to me.

>> Thus, the Jitter RNG is changed to be only bound statically into the
>> kernel removing the option to compile it as module.
>>
>> Reported-by: Christoph Hellwig <hch@infradead.org>
>> Signed-off-by: Stephan Mueller <smueller@chronox.de>
>> ---
>>  crypto/Kconfig | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/crypto/Kconfig b/crypto/Kconfig
>> index 094ef56ab7b4..5b20087b117f 100644
>> --- a/crypto/Kconfig
>> +++ b/crypto/Kconfig
>> @@ -1853,7 +1853,7 @@ config CRYPTO_DRBG
>>  endif  # if CRYPTO_DRBG_MENU
>>
>>  config CRYPTO_JITTERENTROPY
>> -       tristate "Jitterentropy Non-Deterministic Random Number Generator"
>> +       bool "Jitterentropy Non-Deterministic Random Number Generator"
>>         select CRYPTO_RNG
>>         help
>>           The Jitterentropy RNG is a noise that is intended
>> --
>> 2.26.2
>>
>>
>>
>>