It was brought to my attention [0] that we probably should be checking for the OSXSAVE bit instead of the XSAVE bit when determining whether there's support for the XGETBV instruction. IIUC that should indicate that both the OS and the processor have XGETBV support (not just the processor). I've attached a one-line patch to fix this.
[0] https://github.com/pgvector/pgvector/pull/519#issuecomment-2062804463 -- Nathan Bossart Amazon Web Services: https://aws.amazon.com
diff --git a/src/port/pg_popcount_avx512_choose.c b/src/port/pg_popcount_avx512_choose.c index ae3fa3d306..cc3e89e096 100644 --- a/src/port/pg_popcount_avx512_choose.c +++ b/src/port/pg_popcount_avx512_choose.c @@ -74,7 +74,7 @@ pg_popcount_avx512_available(void) #else #error cpuid instruction not available #endif - if ((exx[2] & (1 << 26)) == 0) /* xsave */ + if ((exx[2] & (1 << 27)) == 0) /* osxsave */ return false; /* Does XGETBV say the ZMM registers are enabled? */
