Checking for SSE / SSE2 support

drivingon9 · 11-12-2003, 01:09 PM

In a program, does anyone know how one would check for SSE / SSE2 support being enabled in the OS without using exception handling/signals?

Thanks for any help!!
drivingon9

evil_Tak · 11-12-2003, 01:19 PM

You might want to check out the code MPlayer uses for runtime cpu detection.

jpc82 · 11-13-2003, 09:46 AM

Would it be possible to just read in /proc/cpuinfo and search for "sse" or sse2"

TheOneKEA · 11-13-2003, 10:21 AM

Using /proc/cpuinfo is implicitly discouraged by the kernel folks, since the API may change in a nanosecond and is thus not stable, even though it has been for a longish while. Under 2.6, sysfs might have the CPU flags somewhere in an easy-to-parse place, but I doubt it.

See the mplayer program for how it detects SSE and SSE2.

drivingon9 · 11-13-2003, 11:02 AM

Unfortunately, MPlayer uses signal handling. It executes an SSE/SSE2 instructions and catches the exception if the OS doesn't handle it. I was wondering if there was a cleaner way to do it.

Thanks.

MartinN · 11-13-2003, 01:04 PM

Use the assembler instruction CPUID

I found a small C program here that does pretty much exactly what you want:
http://www-ti.informatik.uni-tuebing...heim/software/

Martin

drivingon9 · 11-13-2003, 05:31 PM

Quote:

Originally posted by MartinN
Use the assembler instruction CPUID

I found a small C program here that does pretty much exactly what you want:
http://www-ti.informatik.uni-tuebing...heim/software/

Martin

Can't do that.

CPUID will tell you whether the CPU supports SSE/SSE2, but not the OS.
The OS (linux in this case) can have SSE and/or SSE2 disabled.

MartinN · 11-14-2003, 05:42 AM

Quote:

Originally posted by drivingon9

The OS (linux in this case) can have SSE and/or SSE2 disabled.

That was new to me. What do you mean by that? Is it possible for the OS to turn off certain instructions in the CPU, or is it just a question of whether the shared libs are compiled with SSE support?

Martin