Processor frequency in SMBIOS

[sudomateo]

When I was developing the Omni infrastructure provider for Oxide it was noted in siderolabs/omni#1633 (reply in thread) that Oxide SMBIOS data doesn't contain processor frequency.

This wasn't a blocker but it was surprising since my local testing showed the processor frequency in Omni and when I moved testing to Oxide I no longer saw processor frequency, making me think that I missed something during implementation.

This issue is to add processor frequency information to SMBIOS. See the Unknown, Not Provided, and Not Specified information below.

$ sudo dmidecode --type processor
# dmidecode 3.5
Getting SMBIOS data from sysfs.
SMBIOS 2.7 present.

Handle 0x0300, DMI type 4, 42 bytes
Processor Information
        Socket Designation: Not Specified
        Type: Central Processor
        Family: Zen
        Manufacturer: Advanced Micro Devices, Inc.
        ID: 11 0F A0 00 FF FB 8B 17
        Signature: Family 25, Model 1, Stepping 1
        Flags:
                FPU (Floating-point unit on-chip)
                VME (Virtual mode extension)
                DE (Debugging extension)
                PSE (Page size extension)
                TSC (Time stamp counter)
                MSR (Model specific registers)
                PAE (Physical address extension)
                MCE (Machine check exception)
                CX8 (CMPXCHG8 instruction supported)
                APIC (On-chip APIC hardware supported)
                SEP (Fast system call)
                MTRR (Memory type range registers)
                PGE (Page global enable)
                MCA (Machine check architecture)
                CMOV (Conditional move instruction supported)
                PAT (Page attribute table)
                PSE-36 (36-bit page size extension)
                CLFSH (CLFLUSH instruction supported)
                MMX (MMX technology supported)
                FXSR (FXSAVE and FXSTOR instructions supported)
                SSE (Streaming SIMD extensions)
                SSE2 (Streaming SIMD extensions 2)
                HTT (Multi-threading)
        Version: AMD EPYC 7713P 64-Core Processor
        Voltage: Unknown
        External Clock: Unknown
        Max Speed: Unknown
        Current Speed: Unknown
        Status: Populated, Enabled
        Upgrade: Unknown
        L1 Cache Handle: Not Provided
        L2 Cache Handle: Not Provided
        L3 Cache Handle: Not Provided
        Serial Number: Not Specified
        Asset Tag: Not Specified
        Part Number: Not Specified
        Core Count: 4
        Core Enabled: 4
        Thread Count: 4
        Characteristics:
                64-bit capable
                Multi-Core

[rmustacc]

Since we're admitting that we're a 7713P in this case, it may make sense; however, I think it'll become more and more of a lie going forward as we have a set of more diverse offerings and CPUs where this'll change in the face of migration and not even be a constant. I think /proc/cpuinfo will still show it and uses mperf/aperf to figure that out perhaps.

[iximeow]

Yes, Omicron#9043 for Turin uses a more generic brand string and doesn't have any cache information that we give for Milan guests today. My hope was to have a Milan v2 CPU type that does similar here in fact.

We don't let guests get at aperf/mperf for a few reasons so /proc/cpuinfo uses the boot-time calibrated TSC rate as CPU frequency. It's a reported bit below host base frequency on Oxide ime and also has the issues in the face of migration.