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core/sys/info: Workaround extremely rare XGETBV issues

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Someone ran into this on Discord, so adopt the same workaround that
chrome did, by checking both OSXSAVE and XSAVE before calling XGETBV.

The old way of detecting AVX is correct per Intel, but such is life.
This commit is contained in:
Yawning Angel
2023-05-16 22:56:16 +09:00
parent bb4ff84a4a
commit adb4692ce8
1 changed files with 8 additions and 1 deletions
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core/sys/info/cpu_intel.odin
+8 -1
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@@ -74,8 +74,15 @@ init_cpu_features :: proc "c" () {
return
}
// In certain rare cases (reason unknown), XGETBV generates an
// illegal instruction, even if OSXSAVE is set per CPUID.
//
// When Chrome ran into this problem, the problem went away
// after they started checking both OSXSAVE and XSAVE.
//
// See: crbug.com/375968
os_supports_avx := false
if .os_xsave in set {
if .os_xsave in set && is_set(26, ecx1) {
eax, _ := xgetbv(0)
os_supports_avx = is_set(1, eax) && is_set(2, eax)
}