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Re: SSE on PIII - gcc or gas bug?
- To: Ilan Finci <ifinci at mobileye dot com>
- Subject: Re: SSE on PIII - gcc or gas bug?
- From: Alan Modra <alan at SPRI dot Levels dot UniSA dot Edu dot Au>
- Date: Tue, 18 Jan 2000 19:47:37 +1030 (CST)
- cc: bug-gnu-utils at gnu dot org, bug-gcc at gnu dot org
On Tue, 18 Jan 2000, Ilan Finci wrote:
> I'm trying to use the new Pentium III extension (SSE - what came after
> MMX) using inline assembly.
>
> I managed to get the program to compile just fine (no warning or
> errors), but when trying to run the program, I get an error "Illegal
> instruction (core dumped)". I've tried it on more then one PIII.
>
> I've checked that SSE is enabled (using CPUID, with ax=1 and checking
> the 25th bit of dx) - it is enabled.
To run SIMD instructions you need to check that
a) CPUID.XMM(EDX bit 25) = 1
(processor supports Streaming SIMD Extensions)
b) CR0.EM(bit 2) = 0
(emulation disabled)
c) CR4.OSFXSR(bit 9) = 1
(OS supports saving SIMD floating-point state during context switches)
Maybe you're missing b) or c)? I also recommend a newer binutils
http://sourceware.cygnus.com/binutils/ or
ftp.varesearch.com/pub/support/hjl/binutils/