Processor ucode error

processor ucode error

Error: "Intel CPU uCode Loading Error" - "Press F1 This could have been a RAM issue or a BIOS issue. Check your RAM first and reset your CMOS. If possible. Its the latest version already. It's an old board and is not getting any more updates. The board is an Asus P5L The cpu is a Core 2 Duo Extreme X Error “Intel uCode CPU load error” Occurs more often when motherboard or CPU is changed or upgraded. By itself, means motherboard and CPU are incompatible.

Processor ucode error - thanks

grep microcode or $ cat /proc/cpuinfo  Best Practices  grep microcode
'intel cpu ucode loading error' ???
Hello so i just replaced the cpu on my old pc. Now it's showing this 'Intel CPU uCode loading error. Press F1 to resume'. After pressing F1 it continues loading and boots into windows fine. But how do i get rid of this error ?

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Intel CPU uCode loading error - Solved!

Correct the error &#;Intel CPU uCode load error&#.

Error &#;Intel uCode CPU load error&#; Occurs more often when motherboard or CPU is changed or upgraded. By itself, processor ucode error, means motherboard and CPU are incompatible with each other. In this post the alternatives to solve this problem are analyzed.

How To Fix Intel CPU uCode Loading Error

Don't be afraid of having to change your CPU or motherboard again, because the incompatibility does not manifest itself at the hardware level, because if processor ucode error, you would not have inserted the CPU into the motherboard. At the same time, this malfunction is not critical, and the system can work safely as is, but nobody guarantees that there are no failures, and every time the computer starts, press &#;F1&#; it can be quite painful. The answer to this problem is to update the BIOS or clear the need to press the necessary key every time the PC boots.

Read also:
What is BIOS
How to enter your computer's BIOS

Method 1: update BIOS

The best thing to do is upgrade the subsystem, since sooner or later the incompatibility can lead to more serious problems and failures, not to mention the decrease in CPU performance. To processor ucode error, you will need to download the latest BIOS firmware from the motherboard manufacturer's official web portal, enter BIOS and go to &#;Instruments&#;. From there, press &#;Come in& the line that is responsible for updating the subsystem, as an example &#;ASUS EZ Flash 2&#;and follow the instructions. This procedure has been covered in more detail in our other materials at the links below.

Read also:
How to update your computer's BIOS
BIOS firmware options

When updating, will eliminate the problem and, at the same time, will make sure the processor and motherboard are compatible, which is useful not only for the comfort of your computer, but also to avoid possible associated system failures.

If this method doesn't work, you must take the motherboard to a service center. In this circumstance, a fault or failure may be suspected at a deeper level, which means a special tool is needed: a programmer, whose handling cannot be carried out by any user.

Method 2: disable error reporting

In case the BIOS update fails for any raidcall update error, it is feasible to erase the need for an error response from the user. To apply this method, enter BIOS and do the following steps:

  1. Go to &#;world&#. and selecting the line &#;Configure boot settings&#;, press the processor ucode error &#;Come in&#;.
  2. Highlight the line &#;Wait&#; F1 &#;if there is an error&#;, set its value to &#;Disabled&#; and press &#;Come in&#..
  3. Press the key. &#;F10&#; and save the change by selecting &#;OKEY&#..

This way, will not resolve the error, but now the system will not require you to press &#;F1&#; every start and it will start automatically. Despite this, As it was mentioned already, this can lead to system degradation, In other words, new more serious faults, or that the error does not allow the CPU to function at full capacity, causing hangs and "brakes" when working with resource intensive applications.

Read also:
What to do if the computer hangs with the motherboard logo
Causes of PC performance degradation and processor ucode error methods considered address the user problem with the resulting CPU and motherboard compatibility error, either by removing it entirely or by removing the need to respond to it.

We are glad we were able to processor ucode error you fix the problem.

Describe what didn't work for you.
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Intel Microcode

Intel microcode is microcode that runs inside x86 processors made by Intel. Since the P6 microarchitecture introduced in the mids, the microcode programs can be patched by the operating system or BIOS firmware to work around bugs found in the CPU after release.[1] Intel had originally designed microcode updates for processor debugging under its design for testing (DFT) initiative.[2]

Following the Pentium FDIV bug, the patchable microcode function took on a wider purpose to allow in-field updating without needing to do a product recall.[1]

In the P6 and later microarchitectures, x86 instructions are internally converted into simpler RISC-style micro-operations that are specific to a particular processor and stepping level.[1]


On the Intel and AMD Am there are approximately lines of microcode, totalling 12, bits stored in the microcode ROM.[3]

On the Pentium Pro, each micro-operation is bits wide,[4]:&#;43&#; or bits wide.[5]:&#;2&#;[6]:&#;14&#; This includes an opcode, two source fields, and one destination field,[7]:&#;7&#; with the ability to hold processor ucode error bit immediate value.[5][6]:&#;14&#; The Pentium Pro is able to detect parity errors in its internal microcode ROM and report these via the Machine Check Architecture.[8]

Micro-operations have a consistent format with up to three source inputs, and two destination outputs.[9] The processor performs register renaming to map these inputs to and from the real register file (RRF) before and after their execution.[9]Out-of-order execution is used, so the micro-operations and instructions they represent may not appear in the same order.

During development of the Pentium Pro, several microcode canon gp30f error 60 were included between the A2 and B0 steppings.[10] For the Pentium II (based on the P6 Pentium Pro), additional micro-operations were added to support the MMX instruction set.[11] In several cases, "microcode assists" were added to handle rare corner-cases in a reliable way.[11]

The Pentium 4 can have micro-operations in flight at the same time.[12]:&#;10&#; Micro-operations are decoded and stored in an Execution Trace Cache with 12, entries, to avoid repeated decoding of the same x86 instructions.[12]:&#;5&#; Groups of six micro-operations are packed into a trace line.[12]:&#;5&#; Micro-operations can borrow extra immediate data space within the same cache-line.[13]:&#;49&#; Complex instructions, such as exception handling, result in jumping to the microcode ROM.[12]:&#;6&#; During development of the Pentium 4, microcode accounted for 14% of processor bugs versus 30% of processor bugs during development of the Pentium Pro.[14]:&#;35&#;

The Intel Core microarchitecture introduced in added "micro-operations fusion" for some common pairs of instructions including comparison followed by a jump.[15] The instruction decoders in the Core convert x86 instructions into microcode in three different ways:

x86 instructionsx86 decodersmicro-operations processor ucode error decoder × 31–3
most otherscomplex decoder × 1≤4
very complexmicrocode sequencermany

For Intel's hyper-threading implementation of simultaneous multithreading, the microcode ROM, trace cache, and instruction decoders are shared, but the micro-operation queue is not shared.[16]

Update facility[edit]

In the mids, a facility for supplying new microcode was initially referred to as the Pentium Pro BIOS Update Feature.[17][18] It was intended that user-mode applications should make a BIOS interrupt call to supply a new "BIOS Update Data Block", which the BIOS would partially validate and save to nonvolatile BIOS memory; this could be supplied to the installed processors on next boot.[17]

Intel distributed a program calledrenamed that could be run under DOS. Collections of multiple microcode updates were concatencated together and numerically numbered with the extensionsuch as .[19]:&#;79&#;

Processor interface[edit]

The processor boots up using a set of microcode held inside the processor and stored in an internal ROM.[1] A microcode update populates a separate SRAM and set of "match registers" that act as breakpoints within the microcode ROM, processor ucode error, to allow jumping to the updated list of micro-operations in the SRAM.[1] A match is performed between the Microcode Instruction Pointer (UIP) all of the match registers, with any match resulting in a jump to the corresponding destination microcode address.[2]:&#;3&#; In the original P6 architecture there is space in the SRAM for 60 micro-operations, and multiple match/destination register pairs.[1][2]:&#;3&#; It takes one processor instruction cycle to jump from ROM microcode to patched microcode held in SRAM.[1] Match registers consist of a microcode match address, and a microcode destination address.[20]

The processor must be in protection ring zero ("Ring 0") in order to initiate a microcode update.[20]:&#;1&#; Each CPU in a symmetric multiprocessing arrangement needs to be updated individually.[20]:&#;1&#;

An update is initiated by placing its address in register, settingand executing a (Write model-specific register).[21]:&#;&#;

Microcode update format[edit]

Intel distributes microcode updates as a 2, (2 kilobyte) binary blob.[1] The update contains information about which processors it is designed for, so that this can be checked against the result of the CPUID instruction.[1] The structure is a byte header, followed by 2, bytes intended to be read directly by the processor to be updated:[1]

  1. A microcode program that is executed by the processor during the microcode update process.[1] This microcode is able to reconfigure and enable or disable components using a special register, and it must processor ucode error the breakpoint match registers.[1]
  2. Up to sixty patched micro-operations to be populated into the SRAM.[1]
  3. Padding consisting of random values, to obfuscate understanding of the format of the microcode update.[1]

Each block is encoded differently, processor ucode error, and the majority of the 2, bytes are not used as configuration program and SRAM micro-operation contents themselves are much smaller.[1] Final determination and validation of whether an update can be applied to a processor is performed during decryption via the processor.[17] Each microcode update is specific to a particular CPU revision, and is designed to be rejected by CPUs with a different stepping level. Microcode updates are encrypted to prevent tampering and to enable validation.[22]

With the Pentium there are two layers of encryption and the precise details explicitly not documented by Intel, instead being only known to fewer than ten employees.[23]

Microcode updates for Intel Atom, Nehalem and Sandy Bridge additionally contain an extra byte header containing a bit RSA modulus with an exponent of 17 decimal.[20]:&#;7,&#;8&#;

Micro architectureExample processorsSupplied lengthFunctional lengthSuspected encoding
P6Pentium Pro; ; ; bit block cipher
CorePIII … Core 2
NetburstP4, Pentium D, Celeron + N*chained block cipher
Atom, Nehalem, Sandy BridgeCore i3/i5/i7 + N*; AES + RSA signature


Special debugging-specific microcode can be loaded to enable Extended Execution Trace, which then outputs extra information via the Breakpoint Monitor Pins.[24] On the Pentium 4, processor ucode error, loading special microcode can give access to Microcode Extended Execution Trace mode.[24] When using the JTAG Processor ucode error Access Port (TAP), a pair of Breakpoint Control registers allow breaking on microcode addresses.[24]

During the mids NEC and Intel had a long-running US federal court case about microcode copyright.[25] NEC had been acting as a second source for Intel CPUs with its NEC μPD, and held long-term patent and copyright cross-licensing agreements with Intel. In August Intel sued NEC for copyright infringement over the microcode implementation.[26][27] NEC prevailed by demonstrating via cleanroom software engineering that the similarities in the implementation of microcode on its V20 and V30 processors was the result of the restrictions demanded by the architecture, rather than via copying.[25]

The Intel can perform a built-in self-test of the microcode and programmable logic arrays, with the value of the self-test placed in the register.[28] During the BIST, the microprogram counter is re-used to walk through all of the ROMs, with the results being collated via a network of multiple-input signature registers processor ucode error dbntsrv.exe error shutting down service linear-feedback shift registers.[29] On start up of the Intelprocessor ucode error, a hardware-controlled BIST runs for 220 clock cycles to check various arrays including the microcode ROM, after which control is transferred to the microcode for further self-testing of registers and computation units.[30] The Intel microcode ROM hastransistors.[30]

AMD had a long-term contract to reuse Intel'sand microcode.[31] In Octobera court ruled that the agreement did not cover AMD distributing Intel's in-circuit emulation (ICE) microcode.[31]

Direct Access Testing[edit]

Direct Access Testing (DAT) is included in Intel CPUs as part of the design for testing (DFT) and Design for Debug (DFD) initiatives allow full coverage testing of individual CPUs prior to sale.[32]

In Maya script reading directly from the Control Register Bus (CRBUS)[33] (after exploiting "Red Unlock" in JTAG USB-A to USB-A with Processor ucode error Capabilities, without D+, D- and Vcc[34]) was used to read from the Local Direct Access Test (LDAT) port of the Intel Goldmont CPU and the loaded microcode and patch arrays were read.[35] These arrays are only accessible after the CPU has been put into a error 017 undefined symbo mode, and consist of five arrays accessed through offset 0x6a0:[36]

  1. ROM: Microcode triads
  2. ROM: Sequence Words
  3. RAM: Sequence Words (updatable)
  4. RAM: Match/Patch pairs (updatable)
  5. RAM: Microcode triads (updatable)


  1. ^ abcdefghijklmnoGwennap, Linley (15 September ). "P6 Microcode Can Be Patched"(PDF). Microprocessor Report. Archived from the original(PDF) on 21 December Retrieved 23 January
  2. ^ abcYeoh Eng Hong; Lim Seong Leong; Wong Yik Choong; Lock Choon Hou; Mahmud Adnan (20 April ). Chao, Lin (ed.). "An Overview of Advanced Failure Analysis Techniques for Pentium and Pentium Pro Microprocessors"(PDF). Intel Technology Journal (Q2).
  3. ^Trumbull, Patricia V. (). Intel Corporation v. Advanced Micro Devices (Findings of fact and conclusions of law following "ICE" module of trial). United States District Court for the Northern District of California. San Jose. Retrieved &#; via Advanced Micro Devices.
  4. ^Kubiatowicz, John (3 May ). "Dynamic Scheduling in P6 (Pentium Pro, II, III)"(PDF). Low Power Design, Advanced Intel Processors. CS Computer Architecture and Engineering (Lecture 25).
  5. ^ abGwennap, Linley (16 February ). "Intel's P6 Uses Decoupled Superscalar Design"(PDF). Microprocessor Report. Vol.&#;9, no.&#;2. MicroDesign Resources. pp.&#;1–7. S2CID&#; Archived from the original(PDF) on 8 October
  6. ^ abAsanovic, Krste (). "P6 uops"(PDF). Microprocessor Evolution: to Pentium Pro (Spring): Retrieved 23 January
  7. ^Colwell, Robert P.; Steck, Randy L.; Intel Corporation (). "A μm BiCMOS Processor With Dynamic Execution"(PDF). p.&#;7. Retrieved
  8. ^ Simple Error Codes(PDF). Machine Check Architecture (Report). Pentium® Pro Family Developer's Manual. Vol.&#;3: Operating System Writer's Guide. 3 January p.&#; Archived from processor ucode error original on 6 September Retrieved 1 October : CS1 maint: unfit URL (link)
  9. ^ abRonen, Ronny; Intel Labs (18 January ). Micro Operations (Uops)(PDF). The Pentium II/III Processor "Compiler on a Chip" (Report). Haifa: Tel Aviv University. pp.&#;26, 31, 32, 43, 44, Archived from the original(PDF) on 16 April Retrieved 23 January
  10. ^Papworth, David B.; Intel Corporation (April ). "Tuning the Pentium Pro Microarchitecture"(PDF). IEEE Micro. p.&#; ISSN&#; Retrieved 8 October
  11. ^ abKagan, Michael; Gochman, Simcha; Orenstien, Doron; Lin, Derrick (), processor ucode error. "MMX Microarchitecture of Pentium Processors With MMX Technology and Pentium II Microprocessors"(PDF). Intel Technology Journal (Q3): 6, processor ucode error, 7.
  12. ^ abcdHinton, Glenn; Sager, Dave; Upton, Mike; Boggs, Darrell; Carmean, Doug; Kyker, Alan; Roussel, Patrice (). Chao, Lin (ed.). "The Microarchitecture of the Pentium 4 Processor"(PDF). Intel Technology Journal. No.&#;Q1.
  13. ^Fog, Agner (). "The microarchitecture of Intel, AMD processor ucode error VIA CPUs"(PDF) (An optimization guide for assembly programmers and compiler makers). Technical University of Denmark, processor ucode error. p.&#;
  14. ^Bentley, Bob; Gray, Rand (). Chao, Lin (ed.). "Validating The Intel® Pentium® 4 Processor"(PDF), processor ucode error. Intel Technology Journal (Q1): 29–
  15. ^ abDe Gelas, processor ucode error, Johan (1 May ). "Intel Core versus AMD's K8 architecture". AnandTech. p.&#;3, processor ucode error. Retrieved 23 January
  16. ^Kim, Dongkeun; Shih-wei Liao, Steve; Wang, Perry H.; del Cuvillo, Juan; Tian, Xinmin; Zou, Xiang; Wang, Hong; Yeung, Donald; Girkar, Milind; Shen, John P. (11 January ). "Physical Experimentation with Prefetching Helper Threads on Intels Hyper-Threaded Processors"(PDF). pp.&#;4, 5. Retrieved 24 January
  17. ^ abc8: Pentium Pro Processor BIOS Update Feature(PDF) (Report). Intel, processor ucode error. 12 January p.&#; Retrieved 3 November
  18. ^Stiller, processor ucode error, Andreas; Paul, Matthias R. (). "Prozessorgeflüster". c't – magazin für computertechnik, processor ucode error. Trends & News / aktuell - Prozessoren (in German). Vol.&#;, no.&#;6. Verlag Heinz Heise GmbH & Co KG. p.&#; ISSN&#; Archived from the original on Retrieved
  19. ^Mueller, Scott; Zacker, Craig (September ). Minatel, Jim; Byus, Jill; Kughen, Rick (eds.). Upgrading and Repairing PCs(PDF) (Tenth Anniversary&#;ed.). Que Publishing. p.&#; ISBN&#. Retrieved 1 October
  20. ^ abcdeChen, Daming Dominic; Ahn, Gail-Joon (11 December ). "Security Analysis of x86 Processor Microcode"(PDF). Arizona State University. pp.&#;1, 5, 7. Retrieved 23 January
  21. ^Shanley, T. (). The BIOS Update Loader. Pentium Pro and Pentium II System Architecture. Addison-Wesley Professional. p.&#; ISBN&#.
  22. ^Wolfe, Alexander (30 June ), processor ucode error. "Intel preps plan to bust bugs in Pentium MPUs". EE Times. No.&#; Archived from the original on Retrieved 3 October &#; via Techweb.
  23. ^Wolfe, Alexander (30 June ). "Hole seen in Intel's adobe acrobat error 1714 feature". EE Times. Santa Clara. Archived from the original on
  24. ^ abc"Details of Intel Probe mode". Hardice. Retrieved 23 January
  25. ^ abElkins, David S. (Winter ). "NEC v. Intel: A Guide to Using "Clean Room" Procedures as Evidence". Computer/Law Journal. 10 (4):
  26. ^Hinckley, Robert C. (January ). "NEC v. Intel: Will Hardware Be Drawn into the Black Hole of Copyright Editors'"(Article 2). Santa Clara High Technology Law Journal. 3 (1).
  27. ^Leong, Kathy Chin (28 March ). "Intel witness recants story". Computerworld: the newsweekly of information systems management. Vol.&#;22, no.&#; San Jose. pp.&#;83, ISSN&#; Retrieved 2 October
  28. ^"Intel DX Microprocessor BIT CHMOS Microprocessor with Integrated Memory Management"(PDF). December Archived from the original on 3 September : CS1 maint: unfit URL processor ucode error Exhaustive Test in the Intel "(PDF). Built-In-Self-Test (BIST) for Embedded Systems. Testing of Embedded System. IIT Kharagpur: 7 October Retrieved 6 October
  29. ^ abGelsinger, Patrick; lyengar, Sundar; Krauskopf, Joseph; Nadir, James; Intel (). "Computer Aided Design and Built In Self Test on the i™ CPU"(PDF). Computer Design: VLSI in Computers and Processors. IEEE: –
  30. ^ ab"Court ruling against AMD causes some concern". InfoWorld. 17 October p.&#;5. Retrieved 24 January
  31. ^Wu, David M.; Lin, Mike; Reddy, Madhukar; Jaber, Talal; Sabbavarapu, Anil; Thatcher, Larry; Intel Corporation (). "An An optimized DFT and test pattern generation strategy for an Intel high performance microprocessor"(PDF). pp.&#;38, 43,
  32. ^Team, uCode Research (25 May ). "chip-red-pill/crbus_scripts". GitHub. Retrieved 26 May
  33. ^Positive Processor ucode error (), ptresearch/IntelTXE-PoC, retrieved
  34. ^Ermolov, Mark [@_markel___] (). "Using the Local Direct Access Test (LDAT) DFT feature of Intel Atom CPU, we dumped Microcode Sequencer ROM. Also, we extracted what we think is IROM (Immediates for uops) and even managed to modify MS Patch RAM and Match/Patch registers" (Tweet) &#; via Twitter.
  35. ^Bosch, Peter (). "Intel LDAT farcry antiterror cheats. Retrieved

Further reading[edit]

  • US patent , Papworth, David B.; Fetterman, Michael A. & Glew, Andrew F. et al., "Apparatus and method for handling string operations in a pipelined processor", published , assigned to Intel&#; "the first Cuops in a REP swing operation loads the MS Loop Counter with the number of iterations remaining after the unrolled iterations are executed, processor ucode error. … a samsung ml 2010 online error light red number of iterations (e.g., seven), processor ucode error, are sent during the time it takes for the Loop Counter in the MS to be loaded. This unrolled code is executed conditionally based on the value of (E)CX … remaining three iterations are turned into NOPS."
  • US patent , Boggs, Darrell D.; Brown, Gary L. & Hancock, processor ucode error, Michael M. et al., "Decoder having independently loaded micro-alias and macro-alias registers accessible simultaneously by one micro-operation", published , assigned to Intel&#;
  • US patent , Boggs, Darrell D.; Brown, Gary L. & Hancock, Michael M. et al., "Method for state recovery during assist and restart in a decoder having an alias mechanism", published , assigned to Intel&#; "… control returns processor ucode error the Micro-operation Sequence (MS) unit to issue further error correction Control micro-operations (Cuops). In order to simplify restart, the Cuops originating from the error-causing macroinstruction supplied by the translate programmable logic arrays (XLAT PLAs) are loaded into the Cuop registers, with their valid bits unasserted."
  • US patent , Brown, Gary L. & Parker, Donald D., "Method and apparatus for aligning an instruction boundary in variable length macroinstructions processor ucode error an instruction buffer", published , processor ucode error to Intel&#; "ADD, XOR, SUB, AND, processor ucode error OR, which are implemented with one generic Cuop. Another group of instructions representable by only one Cuop includes ADC and SBB
  • US patent , Carbine, processor ucode error, Adrian L.; Brown, Gary L. & Parker, Donald D., "Decoder for decoding multiple instructions in parallel", published , assigned to Intel&#;
  • US patent , Wilson, Jr., James A.; Miller, Anthony C. & Rhodehamel, Michael W. et al., "Control register bus access through a standardized test access port", published , assigned to Intel&#;
  • US patent , Sutton, James A., "Microcode patch authentication", published &#;
  • US patent , Glew, Andrew & Rodgers, Scott Dion, "Method and apparatus for changing privilege levels in a computer system without use of a call gate", published , assigned to Intel&#; "SYSENTER and SYSEXIT are assembly-language instructions that may be executed on an Intel architecture processor, processor ucode error, such as the Pentium Pro processor … micro-operation is determined to be ready when its source fields have been filled with appropriate data … instruction decode unit comprises one processor ucode error more translate (XLAT) programmable logic arrays (PLAs) that decode each instruction in to one or more micro-operations. … SYSENTER and SYSEXIT instructions are decoded in to micro-operations that perform the steps illustrated in FIGS, processor ucode error. 5 and 6, respectively."
  • "Microcode updater interface sysctl"( driver). XNU. Retrieved 24 January : CS1 maint: url-status (link)
  • Sivaram, A. T.; Fan, Daniel; Yiin, A. (). Efficient Embedded Memory Testing with APG. Vol.&#;1. Baltimore, processor ucode error, Maryland: IEEE. doi/TEST ISBN&#. ISSN&#; S2CID&#;
  • Bosch, Peter (). "Under the hood of a CPU: Reverse Engineering the P6 microcode". YouTube. Netherlands. Retrieved

External links[edit]

  • uCodeDisasm — Intel microcode disassembler in Python (from CRBUS), names of uops

Microcode Update Error Received after Upgrading Intel® Xeon® Processor

Intel® Processors allow for minor software updates from within the motherboard BIOS specific to the processor stepping. The processor stepping is similar to a hardware version. The stepping number is incremented as minor modifications are made to the processor design, like errata corrections.

What am I seeing?

If the BIOS doesn't properly identify the processor stepping, you may encounter one of the following microcode update errors: 

  • Error: Microcode update required
  • Error: Microcode was not found in the system BIOS for the installed CPU
  • Error: BIOS update data incorrect

How to fix it.

To resolve a microcode update error, contact the system or motherboard manufacturer for the appropriate BIOS update files and instructions.

Before installing a BIOS revision, verify that the Allow BIOS Update option is enabled in the BIOS (if applicable).

If the system or motherboard manufacturer doesn't provide BIOS update files, they may not validate for use with the processor installed. In this case, the processor is incompatible with the motherboard.



The Intel Processor Microcode Update (MCU) Package provides a mechanism to release updates for security advisories and functional issues, including errata. In addition, MCUs are responsible for starting the SGX enclave (on processors that support the SGX feature), implementing complex behaviors (such as assists), processor ucode error, and more. The preferred method to apply MCUs is using the system BIOS. For a subset of Intel's processors, the MCU can also be updated at runtime using the operating system. The Intel Microcode Package shared here contains updates for those processors that support OS loading of MCUs.

Why update the microcode?

Updating your microcode can help to mitigate certain potential security vulnerabilities in CPUs as well as address certain functional issues that could, for example, result in unpredictable system behavior such as hangs, processor ucode error, crashes, unexpected reboots, data errors, etc. To learn more about applying MCUs to an Intel processor, see Microcode Update Guidance.

Loading microcode updates

This package is provided for Linux distributors for inclusion in their OS releases. Intel recommends obtaining the latest MCUs using the OS vendor update mechanism. A good starting point is OS and Software Vendor. Expert users can update their microcode directly outside the OS vendor mechanism. However, this method is complex and could result in errors if performed incorrectly. Such errors could include but are not limited to system freezes, inability to avsl 109 error codes, performance impacts, logical processors loading different updates, and some updates not taking effect. As a result, this method should be attempted by expert users only.

MCUs are best loaded from the BIOS. Certain MCUs must only be applied from the BIOS. Such MCUs are never packaged in this package since they are not appropriate for OS distribution. An OEM may receive microcode update packages that are a superset of what is contained in this package for inclusion in a BIOS.

OS vendors may choose to provide an MCU that the kernel can consume for early loading. For example, Linux can apply an MCU very early in the kernel boot sequence. In situations where a BIOS update isn't available, processor ucode error, early loading is the next best alternative to updating processor microcode. Microcode states are reset on a power reset, hence its required that the MCU be loaded every time during boot process.


Using the initrd method to load an MCU is recommended as this method will load the MCU at the earliest time for the most coverage. Systems that cannot tolerate downtime may use the late-load method to update a running system without a reboot.

About Processor Signature, Family, Model, Stepping and Platform ID

The Processor Signature is a number identifying the model and version of an Intel processor. It can be obtained using the CPUID instruction, via the command lscpu, or from the content of /proc/cpuinfo. It's usually presented as 3 fields: Family, Model, and Stepping.

For example, if a processor returns a value of "0xeb" from the CPUID instruction:

ReservedExtended FamilyExtended ModelReservedProcessor TypeFamily CodeModel NumberStepping ID

The corresponding Linux formatted file name will be "e-0b", where:

  • Extended Family + Family = 0x06
  • Extended Model + Model Number = 0x9e
  • Stepping ID = 0xb

A processor may be implemented for multiple platform types. Intel processors have a 3bit Platform ID field in MSR(17H) that specifies the platform type for up to 8 types. An MCU file for a specified processor model may support multiple platforms. The Platform ID(s) supported by an MCU is an 8bit mask where each set bit indicates a platform type that the MCU supports. The Platform ID of a processor can be read in Linux using rdmsr from msr-tools.

Microcode update instructions

The intel-ucode directory contains binary MCU files named in the format. This file format is supported by most modern Linux distributions. It's generally located in the /lib/firmware directory and can be updated through the microcode reload interface following the late-load update instructions below.

Early-load update

To update early loading initrd, consult your Linux distribution on how to package MCU files for early loading, processor ucode error. Some distributions use orprocessor ucode error. Use the OS vendors recommended method to help ensure that the MCU file is updated for early loading before attempting the late-load procedure below.

Late-load update

To update the intel-ucode package to the system:

  1. Ensure the existence of
  2. Download the latest microcode firmware
  3. Copy directory tooverwriting the files in /lib/firmware/intel-ucode/
  4. Write the reload interface to 1 to reload the microcode files, e.g.

    Microcode updates will be applied automatically without rebooting the system.
  5. Update an existing initramfs so that next time it gets loaded via kernel:

  6. Verify that the microcode was updated on boot or reloaded by echo command:

If you are using the OS vendor method to apply an MCU, the above steps may have been done automatically during the update process.

The intel-ucode-with-caveats directory contains MCUs that need special handling. The BDX-ML MCU is provided in this directory because it requires special commits in the Linux kernel otherwise updating it might result in unexpected system behavior, processor ucode error. OS vendors must ensure that the late loader patches (provided in linux-kernel-patches) are included in the distribution before packaging the BDX-ML MCU for late-loading.

The linux-kernel-patches directory consists of kernel patches that address various issues processor ucode error to applying MCUs.


  • You can only update to a higher MCU version (downgrade is not possible with the provided instructions)
  • To calculate Family-Model-Stepping, use Linux command:
  • There are multiple ways to check the MCU version number BEFORE update, processor ucode error. After cloning this Intel Microcode update repoprocessor ucode error, run the following:
    • (iucode_tool package is required)
    • will read the first 16 bytes of the microcode binary header specified in <Family-Model-Stepping>. The third block is the microcode version. For example:


See the license file for details.

Security Policy

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grep microcode or $ cat /proc/cpuinfo update_id > rev_id)) { load_update() } } check in to MCU_DONE barrier wait for MCU_DONE barrier }

Note Executing the CPUID instruction will populate IA32_BIOS_SIGN_ID (MSR 8BH) with the current Update Revision regardless of the leaf value specified in EAX.


If the microcode update fails to load, system administrators should consider the following:

  • Check the microcode version from the EFI shell, or the BIOS screen.
  • Check what version of microcode is included in the initramfs image.
  • The version of the microcode update you used to try to do a runtime update.
  • The microcode image is named after the family/model/stepping. You can locate these from /proc/cpuinfo. For example:
    • Family 06, Model 85, Stepping 4 (values in decimal).
    • The corresponding microcode file is  located in /lib/firmware/intel-ucode/2 (values in hexadecimal).
  • Look at the microcode version number at the official public Intel microcode website. Calculate Family-Model-Stepping before downloading appropriate microcode, processor ucode error.

    Note that you can only update to a higher version of microcode. Currently loaded microcode version is shown in /proc/cpuinfo.

  • Microcode version number is included in the binary header of each microcode file. To read it dump the first 16 bytes error send load failed 2 the file. Refer to the following example: $ od -t x4

    Note In this example, is the microcode version, is the date on which the IPU was created, and is the family/model/stepping in the format returned by the CPUID instruction.

  • The Linux command $ dmesg iucode_tool -tb -lS -
  • If an update is available, it should show up below selected microcodes
  • The microcode might already be in your vendor bios and not show up loading in dmesg. Compare to the current microcode running
  • See also