Module cpuid 

CPU feature detection via CPUID instruction.

Provides a CpuInfo struct populated at boot time with vendor, model, feature flags, and XSAVE geometry. All subsequent queries go through host() which returns the cached result.

Structs

CpuFeatures

Logical internal bitmap.

CpuInfo

Cached CPU identification and feature information.

XsaveProfile

Cached extended-state save profile, frozen once at init().

Enums

CpuVendor

Constants

XCR0_AVX

XCR0_HI16_ZMM

XCR0_OPMASK

XCR0_SSE

XCR0_X87

XCR0 component bits.

XCR0_ZMM_HI256

Statics

HOST_CPU 🔒

HOST_DEFAULT_XCR0_CACHE 🔒

Lock-free cache of the host’s default XCR0 mask, written once during init(). Used by normalized_xcr0() in the context-switch hot path to avoid acquiring the HOST_CPU spinlock with interrupts disabled.

INITIALIZED 🔒

PROFILE_AREA_SIZE 🔒

PROFILE_XCR0 🔒

Functions

boot_xsave_profile

Return the frozen XSAVE profile. Before init() (or without XSAVE), returns the conservative FXSAVE baseline (mask=x87|SSE, 512 bytes).

default_xcr0_for 🔒

Pure helper: the XCR0 mask this kernel would enable for info (x87 + SSE always, plus AVX / AVX-512 states when the CPU announces them AND the hardware supports the required XCR0 bits). Shared by init() (pre-lock computation) and host().

detect 🔒

Detect CPU features by interrogating CPUID leaves.

features_to_flags_string

Build a Linux-style flags string from CPU features.

host

Return a clone of the cached host CPU info. Panics if init() not called.

host_default_xcr0

host_default_xcr0_fast

Return the host’s default XCR0 mask from the lock-free cache, falling back to the locked query before init() is complete.

host_uses_xsave

Whether XSAVE is supported by the host.

init

Detect and cache CPU information. Must be called once at BSP boot.

tsc_frequency_khz

Return the host’s default XCR0 mask (all supported features). Safe to call before init() : returns XCR0_X87 | XCR0_SSE if not yet initialized.

xcr0_for_features

Compute the XCR0 mask for a given set of allowed features, clamped to what the host actually supports.

xsave_size_for_info 🔒

Compute the XSAVE area size needed for a given XCR0 mask directly from a CpuInfo, without consulting the global cache (host_uses_xsave/host). This is what init() must use, because the cache is not yet published when init() runs : otherwise AVX/AVX-512 would be given a 512-byte area.

xsave_size_for_xcr0

Compute the XSAVE area size needed for a given XCR0 mask. Falls back to 512 (FXSAVE) if XSAVE is not supported.