On Tue, Dec 22, 2020 at 06:30:48PM +0000, James Cook wrote:
> > + case 0xa6: /* Coffeelake mobile */
>
> The laptop's CPU is an i7-10710U, which I think is in the Comet Lake
> series, not Coffee Lake.
Yes 0xa6 is comet lake.
But we should really do what FreeBSD and Linux do and fallback to
cpuid 0x16 as Intel keeps creating new skylake variants.
The frequency from cpuid 0x15 is Hz, from 0x16 it is MHz.
Untested as I don't have any >= skylake machines.
If you can add a printf to check the value is sane that would
be helpful.
Index: sys/arch/amd64/amd64/tsc.c
===================================================================
RCS file: /cvs/src/sys/arch/amd64/amd64/tsc.c,v
retrieving revision 1.21
diff -u -p -r1.21 tsc.c
--- sys/arch/amd64/amd64/tsc.c 6 Sep 2020 20:50:00 -0000 1.21
+++ sys/arch/amd64/amd64/tsc.c 23 Dec 2020 00:52:03 -0000
@@ -66,14 +66,16 @@ tsc_freq_cpuid(struct cpu_info *ci)
eax = ebx = khz = dummy = 0;
CPUID(0x15, eax, ebx, khz, dummy);
khz /= 1000;
- if (khz == 0) {
+ /*
+ * Fallback to 'Processor Base Frequency' from cpuid 0x16 when
+ * 'nominal frequency of the core crystal clock' from cpuid 0x15
+ * is 0 on >= Skylake
+ */
+ if (khz == 0 && cpuid_level >= 0x16) {
+ CPUID(0x16, khz, dummy, dummy, dummy);
+ khz *= 1000;
+ } else if (khz == 0) {
switch (ci->ci_model) {
- case 0x4e: /* Skylake mobile */
- case 0x5e: /* Skylake desktop */
- case 0x8e: /* Kabylake mobile */
- case 0x9e: /* Kabylake desktop */
- khz = 24000; /* 24.0 MHz */
- break;
case 0x5f: /* Atom Denverton */
khz = 25000; /* 25.0 MHz */
break;
