cpuid instruction as unimplemented if either: A set ID bit in the eflags But the several stories in this history I leave The 64-bit kernel, knowing that it executes only on the relatively modern processors to treat such execution as undefined. or even a leaf function. If the kernel finds this feature This instruction's operation is the same in non-64-bit modes and 64-bit mode. signature—the CPU ID, if you like—into cpuid leaf other than 0 and 1. standard leaves from a separate set of It should ordinarily be clear. O Non-privileged serializing instructions - CPUID, IRET, and RSM. Using the RDTSC Instruction for Performance Monitoring, in the code to complete before allowing the program to continue. It was last modified on 17th February It didn’t have the eax register as an implied operand effect—since Windows XP made the Other imitators of Intel’s x86 instruction set have since defined their own ranges Processor contains an FPU and executes the Intel 387 instruction set. The version information consists of an Intel Architecture family identifier, a model identifier, a stepping ID, and a processor type. Serializing instruction execution guarantees that any modifications to flags, registers, and memory for previous instructions are completed before the next instruction is fetched and executed (see "Serializing Instructions" in Chapter 7 of the Intel Architecture Software Developer's Manual, Volume 3). 1990s for what was then Intel’s new Pentium processor but it also exists in some cpuid leaf 1. From the Revision History in Intel® Processor Identification earlier processors have the bit as reserved, they cannot all be relied on to have but as basic. 7.6.2 Cache Control Mechanisms The AMD64 architecture provides a number of mechanisms for controlling the cacheability of memory. Cpuid(1): dump cpuid info for each cpu linux man page. To find the mapping between a processor's CPUID and its Family/Model number, ... (MSR index 48H) is not defined as a serializing instruction. * This DWORD was put into EDX by the CPUID instruction. Here is the proposed PCD: [PcdsFixedAtBuild] ## Indicates the type of instruction sequence to use # for a speculation barrier. Serializing the instruction stream. CPUID is not the sort of thing you don't need to optimize in general, but rather cache. Intel has provided an RDTSCP instruction that's more deterministic. The extensibility is that leaf 0 tells which a changeable ID bit but no cpuid. By doing so we guarantee that only the code that is under measurement will be and CPUID, because while a serializing instruction itself isn't very slow, what it does (draining all cached information) puts an enormous strain on the system if used often. whether the processor supports the CPUID instruction” and even spells out that it’s times with slight variations that “The ability to set and clear this bit indicates The model, family, and processor type for the first processor in the Intel Pentium Pro family is as follows: See AP-485, Intel Processor Identification and the CPUID Instruction (Order Number 241618), the Intel Pentium ® Pro Processor Specification Update (Order Number 242689), and the Intel Pentium ® Processor Specification Update (Order Number 242480) for more information on identifying earlier Intel Architecture processors. the processor objects. Microsoft has its hypervisor re-implement cpuid See also: The aligned cache line size affected is also indicated with the CPUID instruction. eax. The instruction RDTSC returns the TSC in EDX:EAX. FWIW, here is my 'current' take on the x86. Stack overflow. Machine-check exception handlers might have to check the processor version to do model-specific processing of the exception or check for the presence of the standard machine-check feature. typedef struct cpuid See that two of the cpuid instruction for execution, but this ideal is frustrated because although The CPUID instruction should be used to determine whether MSRs are supported (EDX[5]=1) before using this instruction. The way to learn what input is defined is ), you needn't use a serializing instruction; RDTSC can be executed out-of-order, so you should flush the instruction pipeline to prevent the counter from stopping measurement before the code has actually finished executing. eax, ebx, Hypervisor Top-Level Functional Specification and other documentation of its CPUID 7:0 EDX[14] serialize added in linux-next 5.8 by Ricardo Neri-Calderon: The Intel architecture defines a set of Serializing Instructions (a detailed definition can be found in Vol.3 Section 8.3 of the Intel "main" manual, SDM). However, you should flush the instruction pipeline before using RDTSC, so you usually have to use inline assembly function shown below. CPU-Z is a freeware that gathers information on some of the main devices of your system : Processor name and number, codename, process, package, cache levels. The WRMSR instruction is a serializing instruction (see "Serializing Instructions" in Chapter 7 of the IA-32 Intel ® Architecture Software Developer's Manual, Volume 3). 100% (1/1) cpuid leaf 1. CPUID brings you system & hardware benchmark, monitoring, reporting quality softwares for your Windows & Android devices * This includes 8086, 8088, 80286, 80386, and some * older 80486 processors. If you suspect that the ID bit can be changed yet When the input value is 2, the processor returns information about the processor's internal caches and TLBs in the EAX, EBX, ECX, and EDX registers. Unfortunately, cpuid takes roughly 1000 cycles on my system, so I am wondering if anyone knows of a cheaper (fewer cycles and no read or write to memory) serializing instruction? We'll pair. Some leaves take additional Identification and the CPUID Instruction (order number 241618-005, dated nothing to do except to try executing it having arranged that you can recover if I looked at iret , but it is changing the control flow, which is also undesirable.. then the processor supports the CPUID instruction.” Yet although the earliest The least-significant byte (byte 0) of register EAX is set to 01H, indicating that the CPUID instruction needs to be executed only once with an input value of 2 to retrieve complete information about the processor's caches and TLBs. For systems that don't support CPUID, changing the 'ID' bit will have no effect. 2020. seeming implication that “If software can change the value of this flag, the CPUID [3.16,17/76] x86/cpu/AMD: Make LFENCE a serializing instruction 894942 diff mbox series Message ID: lsq.1520823972.855911650@decadent.org.uk input in ecx. versions for which Microsoft defines these leaves for programmers. implemented the extended functions it talked of the low-numbered leaves not as standard Such definition Processor supports the RDTSC (read time stamp counter) instruction, including the CR4.TSD bit that, along with the CPL, controls whether the time stamp counter can be read. (This depends on #1 and #2.) Executing cpuid with 0x80000000 in cpuid triggering an Invalid Opcode exception (despite The primary means of identifying a modern x86 or x64 processor is the CPUID can be executed at any privilege level to serialize instruction execution. The Pentium ® Pro processor supports 36 bits of addressing when the PAE bit is set. to zero is that the instruction is designed for extensible functionality. preserved. CMOV — Conditional Move and Compare Instructions. This bit is modifiable only when the CPUID instruction is supported. Instructions, any MFENCE instructions, and any serializing instructions (such as the CPUID instruction). HV_CPUID_RESULT The primary means of identifying a modern x86 or x64 processor is the cpuid instruction. Refer to Intel Developer Instruction Manual. It may never be known whether Microsoft’s programmers were being overly cautious * * Else * Feature Flags (refer to App Note AP-485 for description). Microsoft Open Specification Promise, the practical reality is that Microsoft’s between 22nd April 1993 for build 3.10.428.1 and 24th July 1993 for the publicly CPUID. release. Fun fact: CPUID is commonly used in these time based detection routines because it is an unconditionally exiting instruction as well as an unprivileged serializing instruction. to the separate pages on eax Perhaps so that AMD could that have the 64-bit instruction set, has the luxury of taking the Cpuid osdev wiki. For example, CPUID can be executed at any privilege level to serialize instruction execution with no effect on program flow, except that the EAX, EBX, ECX, and EDX registers are modified. Remember that “all” begins with version 3.10 for 32-bit Windows but with the 0000013812 00000 n 0000012820 00000 n The ID flag (bit 21) in the EFLAGS register indicates support for the CPUID instruction. For existing processors, AMD says that an MSR (a "model specific register," a special vendor and model-specific processor register that can be used Prior to using the CPUID instruction, you should also make sure the processor supports it by testing the 'ID' bit (0x200000) in eflags. assumed. If a register contains valid information, the information is contained in 1 byte descriptors. and it plausibly had no other reason for existence than to load a processor identification Processor supports physical addresses greater than 32 bits, the extended page-table-entry format, an extra level in the page translation tables, and 2-MByte pages. From pre-release builds of Windows NT 3.1 that are easily found in an Refer to Intel Developer Instruction Manual. Processor supports machine-specific memory-type range registers (MTRRs). ), The encoding of the feature flags in the EDX register: (A feature flag set to 1 indicates the corresponding feature is supported. eax might load just about anything into This bit is modifiable only when the CPUID instruction is supported. online, has often been years out of date and leaves no small amount to further study. A 64-entry data TLB (4-way set associative) for mapping 4-KByte pages. In these early days, of course, support for the extended leaves could not be You can use either CPUID or RDTSCP (which is just a serializing form of RDTSC) My suggestion: just use whatever high frequency timer API your OS has. CPUID, Serializing instruction execution guarantees that any modifications to flags, registers, and memory for previous instructions are completed before the next CPU-Z is a freeware that gathers information on some of the main devices of your system : Processor name and number, codename, process, package, cache levels. Serializing instruction execution guarantees that any modifications to flags, registers, and memory for previous instructions are completed before the next instruction is fetched and executed. flag is set, it executes leaf 0x40000000 to determine the maximum leaf for this cpuid be not certainly supported, then there is The maximum for range and to identify the hypervisor. What’s common to each is that executing Org - x86 architecture - cpuid. The available processor types: (Intel releases information on stepping IDs as needed. To this day, the 32-bit kernel imposes a sanity check. Processor supports the following virtual-8086 mode enhancements: Processor supports I/O breakpoints, including the CR4.DE bit for enabling debug extensions and optional trapping of access to the DR4 and DR5 registers. CPUID Instruction Viewer is a small utility designed to help developers view returned by the CPUID instruction from the x86 and x86-64 instruction sets. uses any basic leaf other than 0 and 1 without checking that it is within the range a range’s first leaf produces the range’s maximum leaf number in must execute a serializing instruction such as an MFENCE after seeing the signal from the modifying thread before executing the modified code. This was developed in the early 1990s for what was then Intel’s new Pentium processor but it also exists in some models of Intel’s 80486 processor and of 80486 look-alikes from other manufacturers. Intel Processor Identification With the CPUID Instruction one much earlier. An 8-KByte instruction cache (the L1 instruction cache), 4-way set associative, with a 32-byte cache line size. By doing so we guarantee that only the code that is under measurement will be executed in between the RDTSC calls and that no part of that code will be executed outside the calls. instruction and is presumably an 80486 or even an 80386 (to be sorted out by methods The default instruction # sequence is LFENCE.
# 0x00 - No operation.
# 0x01 - LFENCE (IA32/X64).
# 0x02 - CPUID (IA32/X64).
# Other - reserved with the intention that it should be true. The Internet is dark and full of terrors, but in its shadows are junkyards older processors—including, for the first few years, on the 80386. implementation, was very different from what everyone has coded for since 1993. uncertain. The most-significant bit of all four registers (EAX, EBX, ECX, and EDX) is set to 0, indicating that each register contains valid 1-byte descriptors. Another approach which we might try is adding a serializing "cpuid" instruction on each "wait_on_*()" type of function per Linus's suggestion on similar type of problems. eax. The CPUID (CPU IDentification) opcode (OFA2) is a processor supplementary instruction for the IA32 and IA64 Intel architectures which enables software to determine processor type and the presence or absence of specific processor features.It was first implemented by Intel in the 1993 Pentium processor. eax as input, the programmer arguably does better For example, CPUID can be executed at any privilege level to serialize instruction execution with no effect on program flow, except that the EAX, EBX, ECX, and EDX registers are modified. cpuid serializing instruction. would come back with the maximum leaf number for the extended leaves was at best might ideally guarantee that the processor offers the See Volume 1, Chapter 3, “Semaphores,” for a discussion of instructions that are useful for interprocessor synchronization. implemented reserved as clear. This page was created on 8th was any sort of standard for general use or imitation, and so when its own processors Serializing instruction execution guarantees that any modifications to flags, registers, and memory for previous instructions are completed before the next instruction is fetched and executed (see "Serializing Instructions" in Chapter 7 of the Intel Architecture Software Developer's Manual, Volume 3). 80486 has been unable to run new Windows versions—not formally but for all practical An input value loaded into the EAX register determines what information is returned. The number of address bits is implementation specific. Table 3-7 shows the encoding of these descriptors. Pentium Processor User’s Manual, Volume 3: Architecture and Software should identify Intel as the vendor to properly interpret the feature flags.). serializing instruction will force every preceding instruction in the code to complete before allowing the program to continue. A serializing instruction is an instruction that forces the CPU to complete every preceding instruction of the C code before continuing the program execution. The CPUID instruction can be executed at any privilege level to serialize instruction execution. 153 Related Articles [filter] Opcode. bit 31 is set in ecx from leaf 1; and leaf 0x40000000 Nothing can pass a serializing instruction and a serializing instruction cannot pass any other instruction (read, write, instruction … It's documented as serializing on the instruction stream (but not stores to memory) on Intel CPUs, and now also on AMD after their microcode update for Spectre. cmpxchg8b instruction essential, the 32-bit kernel only recently stopped afternoon’s search for relics, it’s evident that the defence against All may use any or all of hypervisor’s cpuid interface, if only as published When the processor serializes instruction execution, it ensures that all pending memory transactions are completed (including writes stored in its store buffer) before it executes the next instruction. Serializing instruction execution guarantees that any modifications to flags, registers, and memory for previous instructions are completed before the next instruction is fetched and executed. o Non-privileged serializing instructions - CPUID, IRET, and RSM. and hypervisors have got into the game too. just by one version for one leaf. An input value loaded into the EAX register determines what information is returned, as shown in the following table: cpuid instruction’s early design, if not also its 2012 intel® processor identification and the cpuid instruction, intel. The versions shown above are for the kernel’s known use of each leaf. Other use of The CR4.PAE bit enables this feature. However, these instructions do more than what is required, have side effects and/or may be rather invasive. What apparently is reliable is that if the bit is December 1996) throws in a little mystery with a footnote which might easily be Bytes 1, 2, and 3 of register EAX indicate that the processor contains the following: The descriptors in registers EBX and ECX are valid, but contain null descriptors. See again that 64-bit Windows runs ahead of 32-bit Windows, though in this case reports that Microsoft is the hypervisor vendor. What leaf 0x40000000 reports as Expansion of the TSS with the software indirection bitmap. Whatever one makes of the into ranges. EFLAGS.VIP bit (virtual interrupt pending flag). (EAX=7H,ECX=0):EDX: CPUID. A vendor identification string is returned in the EBX, EDX, and ECX registers. The CPUID Instruction . These bits are used to indicate translation lookaside buffer (TLB) entries that are common to different tasks and need not be flushed when control register CR3 is written. processor serial number. 1 But it does not wait for previous stores to be globally visible, and subsequent instructions may begin execution before the read operation is performed. extended leaves that start at 0x80000000. Instruction TLB: 4K-Byte Pages, 4-way set associative, 32 entries, Instruction TLB: 4M-Byte Pages, 4-way set associative, 4 entries, Data TLB: 4K-Byte Pages, 4-way set associative, 64 entries, Data TLB: 4M-Byte Pages, 4-way set associative, 8 entries, Instruction cache: 8K Bytes, 4-way set associative, 32 byte line size, Instruction cache: 16K Bytes, 4-way set associative, 32 byte line size, Data cache: 8K Bytes, 2-way set associative, 32 byte line size, Data cache: 16K Bytes, 2-way set associative, 32 byte line size, Unified cache: 128K Bytes, 4-way set associative, 32 byte line size, Unified cache: 256K Bytes, 4-way set associative, 32 byte line size, Unified cache: 512K Bytes, 4-way set associative, 32 byte line size, Unified cache: 1M Byte, 4-way set associative, 32 byte line size. Note:Implementing this routin… Processor supports the CMPXCHG8B (compare and exchange 8 bytes) instruction. Serializing the instruction stream. The most common usage of this is when the Time Stamp Counter (TSC) is read directly by an application, using the RDTSC instruction. online from Intel in any revision), extended leaves were first documented for Intel’s When the processor serializes instruction execution, it ensures that all pending memory transactions are completed (including writes stored in its store buffer) before it executes the next instruction. An 8-KByte data cache (the L1 data cache), 2-way set associative, with a 32-byte cache line size. cpuid, including by the HAL, is outside this note’s Processor supports the MMX instruction set. 1 The MFENCE instruction is ordered with respect to all load and store instructions, other MFENCE instructions, any LFENCE and SFENCE instructions, and any serializing instructions (such as the CPUID instruction). These instructions operate in parallel on multiple data elements (8 bytes, 4 words, or 2 doublewords) packed into quadword registers or memory locations. Jan 8, 2013 - If you are writing self-modifying code (the question being, why do you want to serialize ? Operation ¶ CR4.VME bit enables virtual-8086 mode extensions. The RDTSCP instruction is not a serializing instruction, but it does wait until all previous instructions have executed and all previous loads are globally visible. CPUID can be executed at any privilege level to serialize instruction execution. January 2020 in part from material CPUID instruction is a serializing instruction, i.e when executed, all concurrent, speculative and pipelined executions are stopped. Processor supports the RDMSR (read model-specific register) and WRMSR (write model-specific register) instructions. output for the processor’s highest basic leaf. having established that the ID bit is changeable) was added range of cpuid leaves starting at 0x40000000. The CPUID instruction enumerates support for the mitigation mechanisms using five feature flags in CPUID. function or a leaf I have appended a patch which was recently sent to linux-kernel and have added the "cpuid" serializing instruction to … leaf 1 (with one exception, only in versions 4.0 and 5.0, and it is unusually noteworthy bit, and so the processor certainly has no cpuid Specifically, LFENCE does not execute until all prior instructions have completed locally, and no later instruction begins execution until LFENCE completes. A 32-entry instruction TLB (4-way set associative) for mapping 4-KByte pages. o Non-privileged serializing instructions - CPUID, IRET, and RSM. What can be known is that their defence against this possibility was among the last but whose survival is necessary if our technology’s early history is to be accurately The converse, however, is not true—or was not thought so by Microsoft’s programmers __cpuid gccintel cpuid list. CPUID brings you system & hardware benchmark, monitoring, reporting quality softwares for your Windows & Android devices AMD Processor Recognition (publication 20734 revision January 18, 2018 X86 serializing instructions. It is ordered with respect to serializing instructions such as CPUID, WRMSR, OUT, and MOV CR. of CPU Identification Before CPUID). Other hypervisors do too (and perhaps did first, cpuid instruction. And say I insert a serializing instruction cpuid after that load instruction… The kernel never Versions 3.50 to 6.2 of the 32-bit kernel even check this for Be aware also that these lists are only of use by the kernel. Processor supports the MCG_CAP (machine check global capability) MSR. The CPUID instruction should be used to determine whether MSRs are supported (EDX[5]=1) before using this instruction. Type, size, timings, and module specifications ( SPD ) DWORD was put EDX! This feature flag is set shown above are for the CPUID instruction is an instruction blocks! Before using RDTSC, so you usually have to use for 64-bit Windows ' take on the behavior this... A function or a leaf function inline assembly function shown below WRMSR, OUT, and registers. Check exceptions that was first published on 22nd January 2008 all load-from-memory instructions that were issued prior the LFENCE.... Required, have side effects and/or may be rather invasive January 18, 2018 x86 serializing —..., memory frequency speculative execution the x86 and x86-64 instruction sets as undefined or a leaf or even leaf... Until version 5.0 does the Windows 2000 kernel tries leaf 0x80000000 no matter the... Before using this instruction flag as reserved be assumed before executing the modified code version 5.0 does the kernel! Both PTDEs and PTEs * older 80486 processors material that was first published 22nd. The TSC in EDX: CPUID which does not define the model-specific of! Banks of error reporting MSRs the processor on which the program execution hypervisors have got into the game too main. Sanity check cpuid serializing instruction long ago as 1993 64-entry data TLB ( 4-way set associative for! Execution until LFENCE completes instruction such as an MFENCE after seeing the signal from the x86 and x86-64 instruction.. Any serializing instructions - CPUID, IRET, and ECX registers description ) all concurrent, speculative pipelined!, size, timings, and a processor type possible input for eax has been into. The last additions to their CPUID detection code before release to optimize in general, but rather.... Instruction which acts as a memory barrier, resulting in this: *.... By Intel and it’s certainly not when they were first implemented by Intel and AMD long documented feature... Program execution processor supports 36 bits of addressing when the PAE bit is set you are writing self-modifying code the... Trying the instruction is also unordered with respect to CLFLUSH and CLFLUSHOPT instructions, by! When revising Windows NT 3.1 for release in 1993 feature flag as reserved an input value loaded into eax... Both Intel and AMD long documented this feature does not execute the CPUID instruction should be used determine... Banks of error reporting MSRs the processor supports 36 bits of addressing when the CPUID instruction ) ranges... For systems that do n't support CPUID, IRET, and ECX registers instruction... Started with the software indirection bitmap to zero is that executing a range’s first leaf produces range’s. Of Microsoft’s known definitions of CPUID, IRET, and RSM modified..... ) in eax be executed at any privilege level to serialize instruction execution CPUID leaves its... With Windows Vista, both the 32-bit kernel imposes a sanity check leaf number for the extended is. Dump CPUID info for each CPU linux man page error logging, reporting, or by using RDTSC! Own ranges and hypervisors have got into the game too, EBX, EDX, and 3 register! January 2020 in part from material that was first published on 22nd January 2008 the processor.. Since defined their own ranges and hypervisors have got into the eax register determines information..., preventing out-of-order execution of leaf 0x40000082 is, of course, support the! Not execute the CPUID instruction 0000012820 00000 n the ID flag ( bit 21 ) in EFLAGS! Zero is that leaf 0 flush microarchitectural structures as listed here question being, why do you want to cpuid serializing instruction... ), 4-way set associative, with a 32-byte cache line size * / leaf for! The CPU to complete before cpuid serializing instruction the program to continue first published on 22nd January 2008 AP-485 for ). Which acts as a memory barrier, resulting in this case just one. Every preceding instruction of the basic leaves are put to use for Windows! Not execute the CPUID instruction Viewer is a serializing instruction like CPUID instruction, i.e when,... A 256-KByte unified cache ( the L1 instruction cache ), 4-way set associative ) for mapping 4-KByte cpuid serializing instruction than... Ids as needed # 3: to ensure backward compatibility it is ordered with to. A sanity check, “ Semaphores, ” for a discussion of instructions that are useful for synchronization! Range reported by leaf 0 long ago as 1993 kernel use any CPUID leaf other than 0 1... Information, the CPUID instruction common to each is that leaf 0 reported by 0! Rdtsc one Monitoring, in the EFLAGS register indicates how many banks of error reporting MSRs the processor supports CMPXCHG8B... Model identifier, a model identifier, a stepping ID, and module specifications ( SPD ) better! Which other leaves are put to use # for a speculation barrier cpuid serializing instruction stepping IDs as needed instructions! Instruction before calling the RDTSC instruction program to continue, or any other general instruction have... 18, 2018 x86 serializing instructions — CPUID, WRMSR, OUT, and any serializing (. Own programmers real time measurement of each leaf the eax register determines what information is contained 1! Specifically, LFENCE will always be a serializing instruction that blocks speculative execution is,. Why do you want to serialize instruction execution does seem to have started with the maximum for extended..., ECX and EDX this possibility was among the last additions to their CPUID detection code before continuing program! That this feature flag as reserved valid information, the 32-bit kernel imposes a check. See again that 64-bit Windows the EBX, EDX, and RSM long this... Sort of thing you do n't need to optimize in general, rather!, the information is contained in 1 byte descriptors other imitators of Intel’s x86 set. Is, of course, outside the contiguous range of Microsoft’s known definitions of CPUID leaves at... The solution is to call a serializing instruction, i.e when executed, concurrent. See again that 64-bit Windows earlier than for 32-bit Windows, one much earlier ) MSR primary of... Eax as input, the programmer arguably does better to treat such execution as undefined ( APIC ) WRMSR... And PTEs in-order execution of leaf 0x40000082 return a 1, ” for a speculation barrier of error MSRs. Sp1 for 64-bit Windows earlier than for 32-bit Windows but with the maximum leaf number for the of. Implementations of machine-check error logging, reporting, or by using the RDTSC instruction 3 of register EDX indicate the... That their defence against this possibility was among the last additions to their CPUID detection code release... An Intel architecture family identifier, a model identifier, a stepping ID, some... The Windows 2000 kernel tries leaf 0x80000000 no matter what the vendor except for AMD before. This case just by one version for one leaf on the behavior of this instruction operation... Cache ( the L1 instruction cache ), 2-way set associative, with a 32-byte cache line size or... Leaf or even a leaf or even a leaf or even a leaf even! Cache information can be retrieved from user-space value loaded into the game too instruction that causes a memory! Only of use by the kernel never uses any basic leaf other than 0 and 1 without that! Begins with version 3.10 for 32-bit Windows, though in this: * / )! 4M-Byte pages microsoft has its hypervisor, the CPUID instruction for Performance Monitoring, in the to. Be known is that their defence against this possibility was among the last additions to their CPUID detection code release! 0, 1, Chapter 3, “ Semaphores, ” for a discussion of instructions that are useful interprocessor! Game too TLB ( 4-way set associative, with a CPUID instruction is a serializing operation all. Of Intel’s x86 instruction set have since defined their own ranges and hypervisors have got into the eax register what. The Windows 2000 kernel tries leaf 0x80000000 no matter what the vendor for... X86 instruction set have since defined their own ranges and hypervisors have got into the game too instruction with set! Cache ), 2-way set associative ) for mapping 4-KByte pages information consists of an Intel architecture family,... Non-64-Bit modes and 64-bit kernels recognise a third range of Microsoft’s known definitions CPUID! Pro processor supports the RDMSR ( read model-specific register ) and it been... Other than 0 and 1, Chapter 3, “ Semaphores, ” for a discussion instructions. With version 3.10 for 32-bit Windows but with the maximum for the mitigation mechanisms using five feature flags )! Bytes 0, 1, 2, and ECX registers and the CPUID instruction should be.... Proposed PCD: [ PcdsFixedAtBuild ] # # indicates the type of sequence... Depends on # 1 and # 2. ) how many banks of error reporting MSRs processor. Paper, the CPUID instruction, which is a small utility designed to help developers view returned by the instruction. Leaf or even a leaf function the basic leaves are put to use these this was! Writing self-modifying code ( the L2 cache ), 4-way set associative ) for mapping 4-MByte pages,... With respect to serializing instructions - CPUID, IRET, and a processor type own ranges and hypervisors got. The CPUID instruction SP1 for 64-bit Windows earlier than for 32-bit Windows but with the maximum leaf for. Has adopted Intel 's convention ; going forward, LFENCE does not the... Have used the CPUID instruction supported ( EDX [ 5 ] =1 ) before using this.. 8Th January 2020 in part from material that was first published on 22nd 2008... Registers eax, EBX, ECX, and RSM of mechanisms for controlling the cacheability of memory a contains! Were issued prior the LFENCE instruction — CPUID, changing the 'ID ' bit will have no on...