[Mesa-dev] [PATCH] gallium/util: fix nondeterministic avx512 detection

Tim Rowley timothy.o.rowley at intel.com
Wed Jul 19 19:29:38 UTC 2017


cpuid.7 requires cx=0 to select the extended feature leaf.

avx512 detection was using the non-indexed cpuid resulting
in random non-detection of avx512.
---
 src/gallium/auxiliary/util/u_cpu_detect.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/gallium/auxiliary/util/u_cpu_detect.c b/src/gallium/auxiliary/util/u_cpu_detect.c
index 3d6ccb5822..4e71041bc9 100644
--- a/src/gallium/auxiliary/util/u_cpu_detect.c
+++ b/src/gallium/auxiliary/util/u_cpu_detect.c
@@ -438,7 +438,7 @@ util_cpu_detect(void)
           (xgetbv() & (0x7 << 5)) && // OPMASK: upper-256 enabled by OS
           ((xgetbv() & 6) == 6)) { // XMM/YMM enabled by OS
          uint32_t regs3[4];
-         cpuid(0x00000007, regs3);
+         cpuid_count(0x00000007, 0x00000000, regs3);
          util_cpu_caps.has_avx512f    = (regs3[1] >> 16) & 1;
          util_cpu_caps.has_avx512dq   = (regs3[1] >> 17) & 1;
          util_cpu_caps.has_avx512ifma = (regs3[1] >> 21) & 1;
-- 
2.11.0



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