Messages in this thread | | | Date | Thu, 31 May 2012 07:29:11 +1000 | From | Herbert Xu <> | Subject | Re: [PATCH] crypto: serpent - add x86_64/avx assembler implementation |
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On Wed, May 30, 2012 at 05:39:49PM +0200, Andi Kleen wrote: > > I agree with that. Currently when I boot my PC with a new 3.4 kernel all the > > ciphers from the intel-aesni module get loaded whether I need them or not. As > > Jussi stated most people using distros probably won't need the > > serpent-avx-x86_64 module get loaded automatically, so it's probably better to > > leave it that way. > > That means you got a 50% chance to use the wrong serpent.
You should always get the best one available. For example, when you request for "aes" all implementations of it will be loaded by modprobe.
> This was a continuous problem with AESNI and the accelerated CRC, > that is why the cpuid probing was implemented.
The only case where it doesn't work is if you have some variants built-in and the faster ones built as modules. But then the answer is to either build all of them as modules or all of them built-in so that priority-based selection can work.
Can you provide an example where it doesn't work as intended?
What we could do is to use the cpuid-based probing when an algorithm is needed to selectively load the relevant implementations instead of all of them. However, for most algorithms it won't make that big a difference since all the available ones will be loaded 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
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