CTR mode: Kconfig cyclic dependency

CTR mode: Kconfig cyclic dependency

[Stephan Mueller]

Hi Herbert,

during the finalization of my patch set for converting the CTR DRBG over to 
CTR AES, I ran into a Kconfig problem. Maybe you have an idea how to resolve 
it.

As the CTR DRBG now uses the CTR mode, I added "select CRYPTO_CTR" to 
CRYPTO_DRBG_CTR. This now lead to the following cyclic dependency:

crypto/Kconfig:1547:error: recursive dependency detected!
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
crypto/Kconfig:1547:    symbol CRYPTO_DRBG_MENU is selected by 
CRYPTO_RNG_DEFAULT
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
crypto/Kconfig:83:      symbol CRYPTO_RNG_DEFAULT is selected by CRYPTO_SEQIV
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
crypto/Kconfig:255:     symbol CRYPTO_SEQIV is selected by CRYPTO_CTR
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
crypto/Kconfig:286:     symbol CRYPTO_CTR is selected by CRYPTO_DRBG_CTR
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
crypto/Kconfig:1566:    symbol CRYPTO_DRBG_CTR depends on CRYPTO_DRBG_MENU

i.e. CRYPTO_RNG_DEFAULT -> CRYPTO_DRBG_MENU -> CRYPTO_CTR -> CRYPTO_SEQIV -> 
CRYPTO_RNG_DEFAULT

Thanks
Stephan

Re: CTR mode: Kconfig cyclic dependency

[Herbert Xu]

On Thu, Jun 09, 2016 at 11:07:06AM +0200, Stephan Mueller wrote:
> 
> during the finalization of my patch set for converting the CTR DRBG over to 
> CTR AES, I ran into a Kconfig problem. Maybe you have an idea how to resolve 
> it.

Once I finish the skcipher conversion CTR will no longer need SEQIV.
If it's stopping your work right now I think you can just kill the
SEQIV selection by CTR right now since the only user IPsec doesn't
select CTR anyway.

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

Re: CTR mode: Kconfig cyclic dependency

[Stephan Mueller]

Am Sonntag, 12. Juni 2016, 18:58:28 schrieb Herbert Xu:

Hi Herbert,

> On Thu, Jun 09, 2016 at 11:07:06AM +0200, Stephan Mueller wrote:
> > during the finalization of my patch set for converting the CTR DRBG over
> > to
> > CTR AES, I ran into a Kconfig problem. Maybe you have an idea how to
> > resolve it.
> 
> Once I finish the skcipher conversion CTR will no longer need SEQIV.
> If it's stopping your work right now I think you can just kill the
> SEQIV selection by CTR right now since the only user IPsec doesn't
> select CTR anyway.

For now, I use depends on just to ensure a basic consistency. I think I can 
wait for your skcipher conversion.

Thanks.

Ciao
Stephan