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thrustl
Contributor
Contributor

AVX support in guest OS?

Hi,

Recently I purchased a new sandy bridge based laptop (i7-2620M). It is supposed to have AVX instruction support, and CPU-Z confirmed it. But when I check the fedora guest installed in vmware player, it does not show AVX flag in /proc/cpuinfo:

Host is windows 7 SP1 64-bit, does support AVX

Guest is fedora 14 with kernel 2.6.35, does support AVX

vmware player is 3.1.4 build-385536

processor     : 0
vendor_id     : GenuineIntel
cpu family     : 6
model          : 42
model name     : Intel(R) Core(TM) i7-2620M CPU @ 2.70GHz
stepping     : 7
cpu MHz          : 2691.409
cache size     : 4096 KB
fpu          : yes
fpu_exception     : yes
cpuid level     : 13
wp          : yes
flags          : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq ssse3 cx16 sse4_1 sse4_2 popcnt aes lahf_lm ida arat
bogomips     : 5382.81
clflush size     : 64
cache_alignment     : 64
address sizes     : 36 bits physical, 48 bits virtual
power management:

Further gcc test confirmed it: I tried compiling a simple SIMD program with gcc 4.6. When I use -march=native, it does not generate AVX instruction. When I forced with -march=corei7-avx, AVX is generated but when executed, it shows illegal instrction.

My guess is that vmware disabled AVX for guest CPU. Any solutions? I am going to try it on my desktop which is i5-2500K tonight.

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AVX is not virtualized by VMPlayer 3.x.  The first VMware product to virtualize AVX is ESXi 5.0.