On Wed, Dec 23, 2020 at 12:31:10PM +1100, Jonathan Gray wrote:
> 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.
As noticed by tb@ the last diff wasn't quite right:
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 12:25:32 -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 = khz * 1000 * eax / ebx;
+ } 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;
