Asuro/doc/src/arch/x86/arch.x86.cpu.md

arch.x86.cpu

CPU identification, capability detection, clock speed measurement, and feature enablement.

Overview

This unit probes the processor using the CPUID instruction to discover the vendor identifier string, feature flags (EDX and ECX bitmaps from leaf 1), and clock speed. After probing, it enables SSE and AVX if the hardware supports them. The globally accessible CPUID record is populated during init and can be queried by other subsystems at any time. A terminal command handler is also exposed so a shell can display CPU information to the user.

Dependencies

• core.util
• arch.x86.util
• driver.timer.rtc
• io.stdio

Boot Registration

Registered with boot.mgr as arch.x86.cpu at the early barrier.

Types

TCapabilities_Old / PCapabilities_Old

A bitpacked record that maps the EDX output of CPUID leaf 1 to individual Boolean fields. Each field corresponds to one feature bit in the legacy capability word:

Field	Description
FPU	x87 FPU on-chip
VME	Virtual-8086 mode enhancements
DE	Debugging extensions
PSE	Page size extension
TSC	Time-stamp counter
MSR	Model-specific registers
PAE	Physical address extension
MCE	Machine check exception
CX8	CMPXCHG8B instruction
APIC	APIC on-chip
SEP	SYSENTER/SYSEXIT
MTRR	Memory-type range registers
PGE	Page global bit
MCA	Machine check architecture
CMOV	Conditional move instructions
PAT	Page attribute table
PSE36	36-bit page size extension
PSN	Processor serial number
CLF	CLFLUSH instruction
DTES	Debug store
ACPI	ACPI thermal monitor
MMX	MMX technology
FXSR	FXSAVE/FXRSTOR instructions
SSE	Streaming SIMD extensions
SSE2	SSE2 extensions
SS	Self-snoop
HTT	Hyper-threading technology
TM1	Thermal monitor 1
IA64	IA-64 processor
PBE	Pending break enable

Reserved bits (RESV0, RESV1) are included but have no defined meaning.

TCapabilities_New / PCapabilities_New

A bitpacked record that maps the ECX output of CPUID leaf 1 to individual Boolean fields representing newer CPU features:

Field	Description
SSE3	SSE3 extensions
PCLMUL	PCLMULQDQ instruction
DTES64	64-bit DS area
MONITOR	MONITOR/MWAIT
DS_CPL	CPL-qualified debug store
VMX	Virtual machine extensions
SMX	Safer mode extensions
EST	Enhanced Intel SpeedStep
TM2	Thermal monitor 2
SSSE3	Supplemental SSE3
CID	L1 context ID
FMA	FMA extensions
CX16	CMPXCHG16B instruction
ETPRD	xTPR update control
PDCM	Perfmon and debug capability
PCIDE	Process-context identifiers
DCA	Direct cache access
SSE4_1	SSE4.1 extensions
SSE4_2	SSE4.2 extensions
x2APIC	x2APIC support
MOVBE	MOVBE instruction
POPCNT	POPCNT instruction
AES	AES instruction extensions
XSAVE	XSAVE/XRSTOR/XSETBV/XGETBV
OSXSAVE	XSAVE enabled by OS
AVX	Advanced vector extensions
RDRAND	RDRAND instruction

TClockSpeed

TClockSpeed = record
    Hz  : uint32;
    KHz : uint32;
    MHz : uint32;
    GHz : uint32;
end;

Holds the measured CPU clock speed at four granularities. All fields are derived from a single TSC measurement; the coarser fields are obtained by integer division.

TCPUID

TCPUID = record
    ClockSpeed    : TClockSpeed;
    Identifier    : Array[0..12] of Char;
    Capabilities0 : PCapabilities_Old;
    Capabilities1 : PCapabilities_New;
end;

The top-level CPU information record. Identifier is a 12-character null-terminated vendor string (e.g., GenuineIntel). Capabilities0 and Capabilities1 are pointers into the global CAP_OLD and CAP_NEW raw DWORD variables.

Variables

CPUID

var CPUID : TCPUID;

Global CPU information record. Valid after init has been called.

CAP_OLD, CAP_NEW

var CAP_OLD, CAP_NEW : uint32;

Raw 32-bit values of the EDX and ECX registers returned by CPUID leaf 1. CPUID.Capabilities0 and CPUID.Capabilities1 point into these.

Functions and Procedures

init

procedure init();

Initialises the CPU subsystem. Sets up capability pointers, executes CPUID to obtain the vendor string, feature bits, and clock speed, then enables SSE and AVX if supported. Must be called before any other code queries CPUID.

Terminal_Command_CPU

procedure Terminal_Command_CPU(Params : PParamList; stdin_buf, stdout_buf, stderr_buf : POutBuf);

Shell command handler. Writes CPU vendor, clock speed (MHz), and the full capability string to stdout_buf. Intended to be registered with the terminal command dispatcher.

Notes

• Clock speed is measured by counting TSC ticks across one RTC second boundary. If the TSC capability bit is not set, the clock speed is reported as zero.
• SSE enablement clears the EM bit and sets the MP bit in CR0, then sets the OSFXSR and OSXMMEXCPT bits in CR4.
• AVX enablement requires both the AVX and XSAVE capability flags; it sets CR4.OSXSAVE and then calls XSETBV to enable x87, SSE, and AVX state components in XCR0.