On May 16 2013, at 10:31 , David Chase wrote:

> 
> On 2013-05-16, at 12:17 PM, Mike Duigou <mike.dui...@oracle.com> wrote:
>> I haven't looked at the details for the PCLMULQDQ instruction but a caryless 
>> multiply could be of use to some of the crypto primitives as well (GHASH, 
>> GMAC and probably others). Perhaps the property could be 
>> "sun.hotspot.x64.clmulSupported" or something less specific to the usage.
> 
> Note that the instruction also works on 32-bit, and once the builds all use 
> sufficiently modern compilers, the same source code works for both.

Understood, but it's only going to be available on processors that support also 
support EMT64, correct? I am not sure what the best way to characterize the 
required architecture should be.

>> What's our actual experience with needing switches like -XX:-UseCLMUL 
>> or-XX:-UseAVX for other features? Faulty implementations? Feature 
>> misreporting? Performance regressions? Virtualization interactions?
> 
> I haven't seen any virtualization problems -- I've also been testing on VMs, 
> Ubuntu and Solaris on VMWare.
> Should I also give it a go in VirtualBox?  What should I be looking for?

I don't know of any specific problems but was more curious whether we really 
need the ability to disable the feature. Have we seen problems in the past?

> David
> 

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