Re: Architecture Nomenclature
On Mi, Apr 28, 2010 at 02:07:56 (CEST), Kip Warner wrote:
> On Wed, 2010-04-28 at 00:32 +0200, Benjamin Drung wrote:
>> The best solution would be autodetection of SSE2 on runtime. That can
>> done with a few lines of code.
> You're right, that can indeed be done with a few lines of code. e.g.
> cpuid instruction.
SSE2 can be disabled for userland in the kernel. The implementation of
 requires this for example.
more safe approach include:
- "avcodec": installing a SIGILL handler to divert some function
- "vlc": spawning a child process that does some sse instructions and
check if it dies.
> The problem is that you then have to perform a branch every time you
> could potentially use hardware acceleration: a condition for when,
> say, SSE2 is available, and another for a generic implementation.
> It isn't ideal performance wise.
If you have both an SSE2 and C only implementation, you can use function
pointers that are set once, not every time the function is called. If
properly implemented, this hardly impacts performance.
> Perhaps for 32-bit x86 architectures where SIMD is required, I could
> build the package for i686 and have it detect at runtime before said is
> actually used, whether it is available or not. If it is not, raise a
> user visible error and terminate.
This can be implemented as SIGILL handler.
> This method assumes the user knows that it is only supported on P4 or
> later generation of x86.
Reinhard Tartler, KeyID 945348A4