[openssl-users] Openssl and floating point

Jakob Bohm jb-openssl at wisemo.com
Wed Aug 10 15:52:46 UTC 2016

(Top posting for consistency in this part of the thread)

Note, however that emulated floating point tends to add code
size and startup overhead even when not called.

Hence the need to compile with an option to not use floating
point at all, at least on platforms that don't have platform-
specific optimizations via hardware floating point (such as
the SSE optimizations for some operations on x86 or the VFP
optimizations on later ARM hardware types).

Rich suggested a "hackish" preprocessor trick, which depends
on no current or future OpenSSL code using floating point in
a way that is seriously broken by that trick.

On 10/08/2016 16:51, Kyle Hamilton wrote:
> This is compiler-dependent, and because you didn't specify what 
> platform you're targeting or what compiler you're using, there's no 
> way for us to provide an answer. Check your compiler's documentation.  
> GCC, for example, provides software-emulated floating point for 
> platforms without hardware support.  Many other open-source and 
> commercial compilers do as well.
> On Wed, Aug 10, 2016 at 6:26 AM, Kenneth Goldman <kgoldman at us.ibm.com 
> <mailto:kgoldman at us.ibm.com>>wrote:
>     We have a platform that does not support floating point
>     operations.  We discovered that openssl uses floating point in the
>     random number generator.
>     Is there any build or compile time flag that uses an alternative
>     to floating point?


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