Author: avg
Date: Mon Mar 27 09:45:27 2017
New Revision: 316017
URL: https://svnweb.freebsd.org/changeset/base/316017
Log:
add SMT detection for newer AMD processors
The change seems to be more in the nomenclature than in the way the
topology is advertised by the hardware.
Tested by: truckman (earlier version of the change)
MFC after: 2 weeks
Modified:
head/sys/x86/x86/mp_x86.c
Modified: head/sys/x86/x86/mp_x86.c
==============================================================================
--- head/sys/x86/x86/mp_x86.c Mon Mar 27 08:29:46 2017 (r316016)
+++ head/sys/x86/x86/mp_x86.c Mon Mar 27 09:45:27 2017 (r316017)
@@ -255,6 +255,22 @@ topo_probe_amd(void)
pkg_id_shift =
mask_width((cpu_procinfo2 & AMDID_CMP_CORES) + 1);
+ /*
+ * Families prior to 16h define the following value as
+ * cores per compute unit and we don't really care about the AMD
+ * compute units at the moment. Perhaps we should treat them as
+ * cores and cores within the compute units as hardware threads,
+ * but that's up for debate.
+ * Later families define the value as threads per compute unit,
+ * so we are following AMD's nomenclature here.
+ */
+ if ((amd_feature2 & AMDID2_TOPOLOGY) != 0 &&
+ CPUID_TO_FAMILY(cpu_id) >= 0x16) {
+ cpuid_count(0x8000001e, 0, p);
+ share_count = ((p[1] >> 8) & 0xff) + 1;
+ core_id_shift = mask_width(share_count);
+ }
+
if ((amd_feature2 & AMDID2_TOPOLOGY) != 0) {
for (i = 0; ; i++) {
cpuid_count(0x8000001d, i, p);
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