Re: [Valgrind-users] Incorrect results from inline assembly when running under Valgrind

[Tom H. <to...@co...>]

On 11/02/14 09:45, Jeffrey Walton wrote:
> On Tue, Feb 11, 2014 at 4:11 AM, Tom Hughes <to...@co...> wrote:
>> On 11/02/14 08:38, Jeffrey Walton wrote:
>>
>>> Perhpas a --cpu=XXX switch would be helpful for switching between
>>> cpu's. (Forgive me if its non-trivial to do. I know nothing about
>>> Valgrind architecture or operation. I just know a bit about using it
>>> to hunt leaks).
>>
>>
>> There's no point us allowing you to request a CPUID that reports RDRAND
>> support if valgrind is going to bomb out with an unsupported instruction
>> error as soon as you try and execute it.

> RDRAND is easy - back it with /dev/urand.

I wasn't saying it couldn't be implemented, just that it's not as simple 
as just changing what CPUID reports, which seemed to be what you were 
suggesting.

If we supported RDRAND then we would just announce it in CPUID and you 
wouldn't need a --cpu flag.

> AES-NI seems to be the difficult one, and I'm surprised Valgrind
> reports its supported.

It's probably done via a helper so it effectively gets passed through.

Tom

-- 
Tom Hughes (to...@co...)
http://compton.nu/