why does clocked speed show up on arm64 but not on amd64?

From: tech-lists <tech-lists_at_zyxst.net>
Date: Fri, 12 Nov 2021 13:56:35 UTC

WHy does the clocked speed *not* show up on intel hardware in sysctl
dev.cpu ? It shows up in arm64 (ARM Cortex-A72)


% dmesg | grep 42
FreeBSD clang version 12.0.1 (git@github.com:llvm/llvm-project.git
CPU: Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz (4251.32-MHz K8-class CPU)
shows in dmesg as above, but not in the dev.cpu sysctl

% sysctl dev.cpu.0 | less
dev.cpu.0.cx_method: C1/hlt
dev.cpu.0.cx_usage_counters: 1096037
dev.cpu.0.cx_usage: 100.00% last 4436us
dev.cpu.0.cx_lowest: C1
dev.cpu.0.cx_supported: C1/1/0
dev.cpu.0.freq_levels: 3400/84000 3200/77169 3100/73848 2900/67388
2700/61182 2500/55201 2400/52298 2200/46677 2000/41272 1800/36091
1700/34277 1500/29407 1300/24752 1100/20312 1000/18167 800/14031
dev.cpu.0.freq: 3400
dev.cpu.0.temperature: 43.0C
dev.cpu.0.coretemp.throttle_log: 0
dev.cpu.0.coretemp.tjmax: 100.0C
dev.cpu.0.coretemp.resolution: 1
dev.cpu.0.coretemp.delta: 57
dev.cpu.0.%parent: acpi0
dev.cpu.0.%pnpinfo: _HID=none _UID=0 _CID=none
dev.cpu.0.%location: handle=\_PR_.CPU0
dev.cpu.0.%driver: cpu
dev.cpu.0.%desc: ACPI CPU

But on the raspberry pi 4, the overclock shows in the sysctl *only*

% sysctl dev.cpu.0
dev.cpu.0.temperature: 49.1C
dev.cpu.0.freq_levels: 2100/-1 600/-1
dev.cpu.0.freq: 2100
dev.cpu.0.%parent: cpulist0
dev.cpu.0.%pnpinfo: name=cpu@0 compat=arm,cortex-a72
dev.cpu.0.%driver: cpu
dev.cpu.0.%desc: Open Firmware CPU

why the difference? The only place I'm expecting the overclock to not be
present would be on the rpi4, in its dmesg because u-boot hands off to
the OS, and maybe the cpu speed is missed in the handover.

However, I *am* able to see it here, on intel:

hw.clockrate: 4251
machdep.tsc_freq: 4251320612

but i'm puzzled why on intel it's not in dev.cpu.0.freq

The rpi4 doesn't have these two oids