Search results
Results from the WOW.Com Content Network
CPUID should be called with EAX = 0 first, as this will store in the EAX register the highest EAX calling parameter (leaf) that the CPU implements. To obtain extended function information CPUID should be called with the most significant bit of EAX set. To determine the highest extended function calling parameter, call CPUID with EAX = 80000000h.
Takes as input a CPUID leaf index in EAX and, depending on leaf, a sub-index in ECX. Result is returned in EAX,EBX,ECX,EDX. [d] Instruction is serializing, and causes a mandatory #VMEXIT under virtualization. Support for CPUID can be checked by toggling bit 21 of EFLAGS (EFLAGS.ID) – if this bit can be toggled, CPUID is present. Usually 3 [e]
A Linux boot log showing the usage of TSC as system clocksource. The Time Stamp Counter (TSC) is a 64-bit register present on all x86 processors since the Pentium. It counts the number of CPU cycles since its reset. The instruction RDTSC returns the TSC in EDX:EAX. In x86-64 mode, RDTSC also clears the upper 32 bits of RAX and RDX. Its opcode ...
DM&P maintained an embedded Linux distribution customized to use the SoCs features. [6] Other operating systems may work depending on the SoC model, including various RTOS systems such as QNX and VxWorks, Linux distributions, [7] FreeBSD [8] or various versions of Microsoft Windows systems such as Windows Embedded Compact or Windows IoT.
The CPUID instruction can be used on both AMD and Intel CPUs to check whether the RDRAND instruction is supported. If it is, bit 30 of the ECX register is set after calling CPUID standard function 01H. [10] AMD processors are checked for the feature using the same test. [11] RDSEED availability can be checked on Intel CPUs in a similar manner.
With the introduction of the Pentium processor, Intel provided a pair of instructions (RDMSR and WRMSR) to access current and future "model-specific registers", as well as the CPUID instruction to determine which features are present on a particular model. Many of these registers have proven useful enough to be retained.
Intel 5-level paging, referred to simply as 5-level paging in Intel documents, is a processor extension for the x86-64 line of processors. [1]: 11 It extends the size of virtual addresses from 48 bits to 57 bits by adding an additional level to x86-64's multilevel page tables, increasing the addressable virtual memory from 256 TiB to 128 PiB.
The Linux kernel includes full PAE-mode support starting with version 2.3.23, [24] in 1999 enabling access of up to 64 GB of memory on 32-bit machines. A PAE-enabled Linux kernel requires that the CPU also support PAE. The Linux kernel supports PAE as a build option and major distributions provide a PAE kernel either as the default or as an option.