back to article Intel's Skylake and Kaby Lake CPUs have nasty hyper-threading bug

During April and May, Intel started updating its processor documentation with a new errata note – and over the weekend we learned why: the Skylake and Kaby Lake silicon has a hyper-threading bug. The erratum is described in detail on a Debian mailing list, and affects Skylake and Kaby Lake Intel Core processors (in desktop, …

  1. Aitor 1 Silver badge

    Crap quality

    Intel seems really interested in pushing bad quality parts to their customers, are the Managers short on Intel?

    1. RichardB

      Re: Crap quality

      Misread that somewhat... thought you were asking if the Managers are shot at Intel.

      1. wolfetone Silver badge

        Re: Crap quality

        "Misread that somewhat... thought you were asking if the Managers are shot at Intel."

        That might be an idea though...

    2. TReko

      Re: Crap quality

      no, the Managers have a full Intel quotient, that's why they had tried to keep it as quiet as possible.

    3. Anonymous Coward Silver badge

      Re: Crap quality

      No, the phrase is "vertically challenged"

    4. CrazyOldCatMan Silver badge

      Re: Crap quality

      I remember (many, many moons ago, when I worked at a certain cellular base-station manuacturer that used a stylised bat-wing for a logo) having an arguement with the technical architect about the use of non-Intel processors (AMD had just bought out the K6 and I was quite keen on them).

      His answer was to specify that non-Intel processors should never be used "because you knew what you got with Intel and their processors were bug-free".

      The next day Intel revealed the news about the FooF microcode bug.

      Oh, how we laughed.

  2. Shadow Systems Silver badge

    This is gonna suck.

    I can't access the computer unless/until the ScreenReaderEnvironment (SRE) starts talking, & there's no pre-OS-SRE, meaning I can't boot the computer to a SRE in order to get into the BIOS to update this kind of crap even if they DID release a fix that was SRE accessible.

    I'll have to pay a Sighted Techie to do this for me, and that means heading to someplace like BestBuy.

    I *really* don't want anyone at BestBuy touching my computer, I don't trust them as far as I could comfortably shoot one out my arse. =-(

    *HeadDesks in frustration*

    1. Griffo

      Re: This is gonna suck.

      Most BIOS updates are released these days (at least by the big MFG's) as OS executables, so you can run the update inside your OS, it will reboot and flash for you.

      1. Anonymous Coward
        Anonymous Coward

        Re: This is gonna suck.

        Where "OS" = "Windows only", sure. You're going to have a long wait if you want OS X or Linux executables to patch your UEFI.

        1. A Non e-mouse Silver badge

          @DougS Re: This is gonna suck.

          I think you'll find that Apple do something similar to Windows in that they ship a MacOS update that can initiate the UEFI update from within MacOS.

        2. Anonymous Coward
          Anonymous Coward

          Re: This is gonna suck.

          You're going to have a long wait if you want OS X or Linux executables to patch your UEFI.

          For Apple Mac users that's just another patch to run (see this as an older example. Firmware BIOS or UEFI upgrades are generally not hard to do, but they're rare. Other than with Apple where it simply shows up as an update that needs a reboot to complete, few users realise they need it because it's not really part of the Microsoft or Linux update cycle - it's hardware.

          Unless users are in touch with whoever manufactured their hardware, how will they find out? I guess it's easier with Microsoft sourced hardware where the associated subscription will at least provide a point of contact.

          1. Zakhar

            Re: This is gonna suck.

            For Linux, you just need the package intel-microcode.

            You get it with 'sudo apt-get install intel-microcode', or graphically with the dialog box for additional (aka proprietary) drivers. You would use the same dialog box, for example to get the nVidia proprietary drivers instead of Nouveau which is the Open Source implementation for nVidia GPUs.

            Here is what the documentation of the intel-microcode package says:

            This package contains updated system processor microcode for Intel i686 and Intel X86-64 processors. Intel releases microcode updates to correct processor behavior as documented in the

            respective processor specification updates.

            So you just need to wait that you distro updates this proprietary stuff.

            1. This post has been deleted by its author

            2. Anonymous Coward
              Anonymous Coward

              Re: This is gonna suck.

              intel-microcode might help in this limited circumstance (assuming it handles suspend properly) but what about other issues that require UEFI patching, like the recent ME exploit? That can't be fixed through the Linux kernel since it operated below the level of the OS or even a hypervisor. Any laptop that doesn't let you patch UEFI directly that is running Linux needs a Windows partition - that's the only reason I have one on mine.

    2. td97402

      Re: This is gonna suck.

      Do Not Take Your Computer To Best Buy! Call a local community college or college they usually have computer technician training and they have interns.

      1. Doctor Syntax Silver badge

        Re: This is gonna suck.

        "Do Not Take Your Computer To Best Buy!"

        Similar businesses are available in other countries.

    3. Korev Silver badge

      Re: This is gonna suck.

      Could you find one of the job swapping* websites where people swap work and find a techie who can help in return for some of your help doing something else?

      *There's probably a proper name for these.

    4. Anonymous Coward
      Anonymous Coward

      Re: This is gonna suck.

      If you could fix the issue if Screen Reader were working then I am sure you could find someone willing to act as one while you accessed your BIOS.

      While sympathising with your predicament it surely isn't the first time you have ended up needing reading assistance which technology doesn't cater for.

      1. Anonymous Coward
        Anonymous Coward

        Re: This is gonna suck.

        I stand corrected on OS X UEFI updates. I hadn't ever seen them on Intel's site, but it makes sense Apple would distribute them directly.

        You still can't get Linux executables to patch UEFI, if your UEFI doesn't patch itself directly like my laptop's doesn't, you have to keep a Windows partition around just for that purpose.

      2. sarahhart

        Re: This is gonna suck.

        did... you seriously just tell a blind person that you're "sure" they can "find someone" to just be a screen reader?

        if you *really* do sympathise with the difficulties that come with being disabled, then please, heed my advice: comments like the one you just left aren't helpful, and in fact, they are patently unhelpful.

        this person quite obviously knows their living situation and everything associated with it. if there was someone who lived locally enough that would help, that the person trusted, that they would do that? instead, they said their *only* option would be taking it to a store, which they didn't trust with their computer.

        which goes to say that if there were a generic Someone they could ask "to be a screen reader", they probably wouldn't trust that they were only doing what was asked of them too.

        let alone, like... i'm guessing since you post on this site you've had the "joy" of doing tech support for uninitiated family members over the phone? ones who describe what's on screen in such a bizarre way that you have *no* idea what's going on? that's almost certainly what it would be like for this person with a generic Someone, even if such a person were available.

        now, i'm going to assume good faith here, and bring up that: a lot of disabled people (or people with disabilities, depending on what the OP to this chain prefers [people do often prefer one or the other, i usually go with "disabled" for myself rather than "person with disabilities"]) do live independently enough that family and friends don't live anywhere near close enough to just come round and offer support like this on a whim.

        i bring this up because it's still very prevalent in our popular culture the idea that disabled people always have family, or a romantic partner, or some kind of hired carer, available at all times. which is simply not the case for a lot of people (even though there are people who need such 24/7 help) and as such, is generally pretty patronising to say something like what you said, that you're "sure [they] could find someone". why? *what* makes you sure? please take some time to think about that.

        disclaimer: i am sighted, but disabled in other ways. i do not presume to have all the answers of how to speak to blind/Blind people specifically. rather, i am just painfully aware of how people with all kinds of disabilities get given "advice" like "get a friend or neighbour to help you with it", as if it should be normal for someone to just need the charity of an abled person to do something everyone else can do independently.

        1. A Non e-mouse Silver badge

          @sarahhart Re: This is gonna suck.

          I think the most important point you missed is that disabled people* generally don't want to have to depend on other people. Independence is something very powerful and precious to them.

          *Not sure what the correct phrase or terminology is here, sorry. No offense intended.

    5. jtaylor Bronze badge

      Re: This is gonna suck.

      Facetime with a sighted friend who will read the screen to you.

      There's an iPhone app that senses light, so you can even tell when the screen lights up.

      (Equivalent tools are no doubt available on Android and Windows Phone. It's just that all my blind friends use iPhones.)

    6. Jonathan 27

      Re: This is gonna suck.

      Best Buy "technicians" often have no training at all, some might have A+ (which honestly, is a worthless certification). I wouldn't pay them to clean out my cat's box.

    7. TrumpSlurp the Troll

      Re: This is gonna suck.

      So don't use Best Buy.

      Find a local independent.

      You should have plenty of choice.

      Interview them first just to check their knowledge, of course.

  3. Tom 64


    Anyone know how likely this is to occur?

    My work system runs kaby lake, and I'd rather not disable SMT unless really necessary.

    1. Anonymous Coward
      Anonymous Coward

      Re: ugh

      Well, have you seen those symptoms yet? If not...

      Also, look at how long it took them to find this, since it affects all Skylakes it is at least two years since customer testing of Skylakes started, even longer since Intel did internal tests. It can't be all that common or easy to trigger, or it would have been identified a LONG time ago.

      1. patrickstar

        Re: ugh

        Well, on the other hand, how many people actually bother (or are able) to root-cause random crashes to the Point where the microcode can be properly blamed?

        Even if it's a perfectly repeatable crash most people would blame it on application/OS bugs and work around it.

        I'd think that the only people who actually HAVE to hunt down bugs like this would be compiler authors and related fields.

        1. Ramazan

          Re: would be compiler authors and related fields

          Not necessarily. Guys who run performance benchmarks at Tom's Hardware Guide once noticed that newest Intel Pentium III 1333MHz (or was it 1133MHz?) consistently crashed at Linux kernel compilation test.

          Found it on Wikipedia: "A 1.13 GHz version was released in mid-2000 but famously recalled after a collaboration between HardOCP and Tom's Hardware[3] discovered various instabilities with the operation of the new CPU speed grade."


          "When I was testing the Pentium III 1.13 GHz I was also using a GNU/Linux installation to run kernel compilation benchmarks. I had introduced this benchmark in our processor-benchmarking suite only recently and was therefore not too experienced with this operating system. What I knew for sure however was that my Pentium III 1.13 GHz hadn't been able to finish the compilation even once."

      2. Nattrash Silver badge

        Re: ugh

        I agree fully. Looking at the timeline in the Debian message, this has been ongoing for some time. So incidence and significance seem favourable.

        And as for some comments here:

        The latest Dell boxen we have here allow BIOS flash/updates OS independently, because there is the f12 option way before any OS has booted. Just get the update package at Dell and use the update option under F12 during boot. Whether Dell already adapted/ upgraded their BIOS, that is another question of course (quick check for our boxen resulted in a firm no).

        As for Linux - not uncommon, the Linux updates are also coming through with a significant delay. For example, where Debian (from stretch upwards) already have the new intel-microcode, ubuntu still haven't pushed this newer version (for their LTS) yet.

        Then again, as WUSP show, careful review and deployment of updates is always a good thing...

        1. This post has been deleted by its author

      3. Anonymous Coward
        Anonymous Coward

        Re: ugh

        I have had some unexplained major performance issues with a heavily multi-threaded application on a Kaby Lake i7 that do not occur on my Haswell i7 development machine. At times the 3.6GHz Kaby Lake significantly under-performs the 2.2GHz Haswell. I kind of doubt this microcode issue is the cause, it's much more likely to be a bug in my code, but I have been racking my brains and not found the cause yet, so I'm going to disable HT and see what happens.

        1. Alan_Peery

          Re: ugh

          Maybe the processor bug makes a function call fail, and that failure is caught by an exception? Unless the exception logs a message that could be a silent cause of slowness.

      4. Tom 64

        Re: ugh

        > "or it would have been identified a LONG time ago."

        It may well have been found a long time ago. Trouble is, intel have a habit of sitting on information like this so as not to harm their channel partners (who would have to dump stock), and themselves who may have to issue a huge buyback.

        Better to wait and bury the head in the sand while the engineers can figure out if it can be fixed in the field.

      5. Robert Heffernan

        Re: ugh

        Having read the documentation on the issue, it's certainly triggerable given the right circumstances.

        1. You need to be in a loop with less than 64 instructions in the loop

        2. You need to write to specific registers within that loop

    2. Voland's right hand Silver badge

      Re: ugh

      I have a laptop given to me by IT sitting in the corner. As anything handed out by corporate IT it is an Intel. To be more exact Hell with Skylake. I do not recall a "hyperthreading off" toggle in the BIOS though...

      I had to put it on extended leave because it was showing some seriously weird behavior with Java coredumping. I suspect it is the same bug. Based on its behavior I would say - every couple of hours under heavy load.

    3. Roland6 Silver badge

      Re: ugh

      >Anyone know how likely this is to occur?

      Agree, if I understand the problem correctly, it should be causing user visible random system glitches and instability. Thus given the number of PC's running Windows it is correct to ask why we aren't seeing a lot of feedback about random Windows faults etc.

      Additionally, whilst I don't know the extent to which the OCaml compiler is used, we should also be questioning whether there something the OCaml compiler is doing (with respect to hyper-threading) that Windows and other compilers aren't doing.

  4. David Pearce

    Disabling Hyperthreading turns an I7 into an I5. How is Intel going to compensate for this?

    1. Anonymous Coward
      Anonymous Coward

      There was a Pentium bug many years ago - IIRC in floating point arithmetic. Intel eventually offered a free replacement cpu with courier collection of the old one.

      1. Korev Silver badge

        Ah yes, "Pentium inside, can't divide"

        1. Anonymous Coward
          Anonymous Coward

          And, as per, Intel sought to minimise the seriousness of the bug.

          Like it only showed up once every so many billion FP executions. Which, of course, translated into pretty damn often in wall clock time.

  5. Mikel

    Disable hyperthreading? Ouch.

    Not a good time for this just as AMD launches Ryzen, Threadripper and EPYC.

    1. GrumpyOldBloke

      Re: Disable hyperthreading? Ouch.

      Ryzen is not without its issues - random freezes.

    2. ArrZarr

      Re: Disable hyperthreading? Ouch.

      Just occured to me - why hasn't Threadripper had an I-for-a-Y-dectomy while Ryzen and epyc both have? Was Threadrypper just too much for even the humorless lot at AMD marketing?

      1. Jonathan 27

        Re: Disable hyperthreading? Ouch.

        Probably because native English speakers would all pronounce that thread-ripe-er.

  6. Chairo

    Linux to the rescue?

    Current Linux distros (Ubuntu from at least 15.04 on) have a "3rd party driver" feature to update the CPU microcode. Both, for AMD and Intel.

    Does this solve the problem? If so, enabling that driver would be a simple workaround.

    I wonder, if a similar feature is available for Windows, too.

    Edit: See also:

    1. Chairo

      Re: Linux to the rescue?

      Hmm, a short search of the microsoft website shows that there is at least a mechanism for microsoft to update the microcode. They seem to deliver it via windows update.

      Perhaps Intel can persuade them to deliver this specific update quickly and with a comprehensive description?

    2. Doctor Syntax Silver badge

      Re: Linux to the rescue?

      "Current Linux distros (Ubuntu from at least 15.04 on) have a "3rd party driver" feature to update the CPU microcode. Both, for AMD and Intel."

      Such mechanisms have existed since the days of oops-I-can't-divide. So why are Debian saying it can't be fixed except by motherboard firmware?

      Does current firmware shut the door on such mechanisms? That might be done for security reasons - block malware that attempts to rewrite microcode - but if so there needs to be a better way to fix it than depending on motherboard manufacturers getting round to distributing upgrades, always assuming they can be bothered.

      1. This post has been deleted by its author

    3. Jon 37

      Re: Linux to the rescue?

      For Skylake, the latest version of the Linux microcode update will fix this.

      But for Kaby Lake, Intel have not released the fixed microcode publicly, it's only available to motherboard manufacturers. So you will have to ask your PC or motherboard vendor for an updated BIOS/UEFI that includes the latest microcode.

      That's Intel's fault for having a fix and not releasing it to the public, there's not much that Debian can do about it.

  7. Anonymous Coward
    Anonymous Coward

    Not good news for the new iMac...

    So the new £5000 iMac Xeon 2017, is well, the same speed as a 2009 i7 iMac 27''?

    Timmy will be happy. He'll be 'Hyper-ventilating'.

    1. td97402

      Re: Not good news for the new iMac...

      Don't get all giddy. Apple will deliver these new systems with the microcode already patched, you can be sure of that.

      1. Anonymous Coward
        Anonymous Coward

        Re: Not good news for the new iMac...

        I am shure you personally can't be shure of that, i.e., you cannot know that.

        Or are you some kind of Apple employee?

      2. Anonymous Coward
        Anonymous Coward

        Re: Not good news for the new iMac...

        Don't get all giddy. Apple will deliver these new systems with the microcode already patched, you can be sure of that.

        They don't have to. As soon as the user has done first setup it will run the update and pull in the relevant patches since production, update, possibly reboot and that will be that.

        Sure, what is produced now (well, in a few days from now) may be supplied pre-patched already, but there's no point in opening up existing stock, that would be silly :). There is also the problem that something new may have shown up by then :)

    2. Steve Davies 3 Silver badge

      Re: Not good news for the new iMac...

      The Screen is a whole lot better as is the GPU than the 2009 version but you don't seem to care.

      And the problem is probably temporary so won't affect many people (who buys iMac's these days eh?).

      but you seem to really not like Apple so carry on hating them even though this problem does not lie with apple but Intel.

    3. gnasher729 Silver badge

      Re: Not good news for the new iMac...

      "So the new £5000 iMac Xeon 2017, is well, the same speed as a 2009 i7 iMac 27''?"

      It will have eight cores instead of four, at higher clock speed, so it will be an awful lot faster.

      It is also supposed to ship in December 2017, and we might assume that Intel will get its act together and ship a fixed product by then.

      1. Aitor 1 Silver badge

        Re: Not good news for the new iMac...

        It will be great.

        The screen is the same as my iMac 5k, so very nice.

        My iMac does have some cooling issues.. if I compile for 5 minutes, it will get quite warm and the fam will spin madly, I wonder how much noise/heat issues will de Xeons have.. will they throttle while rendering?

        As for rendering, etc.. well, I would rather have a threadripper, much faster and cheaper. But sure not as pretty, and if you like Mac OS...

  8. Gene Cash Silver badge

    intel-hyperthreading package?

    Don't you mean the intel-microcode package?

  9. Destroy All Monsters Silver badge

    Intel "can only"

    This can only happen when both logical processors on the same physical processor are active.

    Combustion can only happen if air contains oxygen


    What happened to the Intel Management Engine built-in remotely accessible management server bug Intel SA-00075? It has dropped off the radar quickly.

  10. Primus Secundus Tertius Silver badge

    Microcode is hard

    In about 1981 a computer manufacturer - not Intel - trained me and a colleague (we were in an outside company) to create new microcode for their processor.

    Microcode is hard. Components of the CPU are running in parallel, some taking several clock cycles, and the microcode designer must take account of these things.

    I am sure modern Intel CPUs are much more complicated than anything from 1981. I hope they have better development tools, including simulators, than we did. But now I wonder if there are bugs or design weaknesses in those tools.

    Or, I suppose, it could just be undue timescale pressures on the microcoders.

    1. Anonymous Coward
      Anonymous Coward

      Re: Microcode is hard

      In 1966 the RCA Spectra 70/45 mainframe had microcode that could be software selected for either IBM 360 compatible mode - or second generation RCA 501 (English Electric KDF8) mode.

      The ICL 2903 mini-computer range was programmed at microcode level.

      The IBM 370 compatible mainframes like the Fujitsu/ICL Atlas range in the 1980s had microcode that could be loaded from floppy disc. This offered various processing speed upgrades as and when the customer required them - without major disruption.

    2. Anonymous Coward
      Anonymous Coward

      Re: Microcode is hard

      From a vague memory, VAXs (730 ???) used to load microcode from tape before booting proper.

      I'm sure the one we ran at Uni did.

    3. Aitor 1 Silver badge

      Re: Microcode is hard

      Been there, done that. Too hard for me, race conditions are crazy.. I would rather have somebody else do that job... I mean, I can do it, but it is REALLY hard.

    4. Down not across Silver badge

      Re: Microcode is hard

      Yes it is. Which reminds me that I should probably re-read Tracy Kidder's excellent book on Eclipse MV/8000.

      1. Anonymous Coward
        Anonymous Coward

        Re: Microcode is hard

        "Which reminds me that I should probably re-read Tracy Kidder's excellent book on Eclipse MV/8000."

        Somewhere in that book is a quote along the lines that at least one person afterwards "went back to the soil" - where things moved more slowly than nanoseconds.

        Having taken a break from IT on a farm for similar 1970s reasons - I was then glad to get back into IT "where things move a lot faster than the seasons".

        The book's subject of the unofficial "backup" development of something also happened in ICL - IIRC with the comms front-end MCU1. Can't remember why the approved new development failed to meet its deadlines - but a skunkwork based on existing hardware was a success.

    5. Anonymous Coward
      Anonymous Coward

      Re: Microcode is hard

      The problem occurs only with active hyperthreading, i.e. when the CPU is executing two different instructions in parallel that are *supposed* to use non-interfering components of the processor. Hard to find that with simulators.

      The code pattern to trigger this bug is also discouraged by Intel Optimization guides as being slow, so probably only coded very rarely by a compiler. Probably not a high priority on simulation experiments until now.

      1. Ian 55

        Re: Microcode is hard

        Or 'We think there's a problem around this, let's discourage people from doing it'.

        One of the issues is apparently that Intel test their processors less than they used to. Taking time to make sure they were behaving correctly was costing money and making them look slow...

  11. Unicornpiss

    Perhaps we've been unfairly blaming Windows..

    ..for the random blue-screens and freezes that nearly every Windows box seems to experience in our organization once in a while. Issues that have happened to our newer Dells with i5s and i7s and that we've never been fully able to eradicate, despite patching/updating everything possible, swapping memory, hardware, etc.

    No excuses or benefit of the doubt though for the utterly awful Windows update process that needs to be taken out back of the barn and shot.

    1. patrickstar

      Re: Perhaps we've been unfairly blaming Windows..

      Sorry to ask, but have you followed the proper well-established procedures for troubleshooting bugchecks? Probably not, since you can't even tell if this issue can be related or not.

      I mean - you are aware that those letters and numbers on the blue screen are there for a reason, aren't you? (Though for serious debugging you will want a kernel dump as well...)

  12. Arthur the cat Silver badge
    Thumb Up

    the fit's hitting the shan

    Tip of the hat for a Roger Zelazny reference.

  13. Uplink

    Kaby Lake and can't disable HT

    I happen to have a rather nice* Dell XPS 8920 at work. Last BIOS is from March. There's no option to disable HyperThreading.

    So far the only things crashing on me are PulseAudio and bluetoothd, and I have no idea if they crash because of this bug or just because there are bugs that need to be ironed out in drivers or the software.

    *It's nice after putting up a good fight when I installed Ubuntu on it. I had to mix and match many Internet forum posts in order to win the battle.

  14. OrdinaryNimda

    Where's the news reporter, you know, the one with the beard?

    I'm just schocked Nostradamus has not even vaguely reported this. We all know the Pentium FDIV bug was a big hit in 1520, so why is there not even a teensie-weensie Quatrain about this one? Not even Hoagland has anything on it (as of this writing). Are we looking at a new conspiracy, stemming from like 500 hundred years ago? (That would make it a 2000-Quarterly financial report Head Fake; must be a record :)

    1. Flakk

      Re: Where's the news reporter, you know, the one with the beard?

      You know that you're not supposed to electronically post that list of random words used to recover your Ethereum wallet, right?

  15. Joerg

    So now AMD to sell Ryzen has to attack Intel finding bugs that highly like don't exist...

    So now AMD to sell Ryzen has to attack Intel finding bugs that highly like don't exist...

    Everything about this new microcode bug affecting Intel CPUs looks beyond fishy. And AMD needs to sell the awful Ryzen products at any cost to not go bankrupt.

    So they come up with these lies to attack Intel trying to tell the world "you see Intel CPUs are not more reliable than ours" ... What a smart masterplan ..uhh! Fact is that AMD lies against Intel and Nvidia always end up being a huge failure. They think everyone buying CPUs and GPUs must be dumb like their so smart marketeers ...

    Heck ! AMD sold the Polaris GPUs out of PCI-E specs that fried the motherboard against any safety standard and then they released a software "fix" with their drivers to slow down the Polaris GPUs to avoid the melt down. THAT is AMD , the ones selling unreliable flawed products.

    1. toughluck

      I have a hard time understanding your post

      Not a word about AMD in the article. Nothing mentioned about GPUs.

      Yet you bring up both topics. And then you add a conspiracy theory about AMD being behind this.

      While I understand that this may be simple trolling or fanboy knee-jerk reaction, I still feel compelled to ask: Why did you actually type that flame out?

      1. Destroy All Monsters Silver badge

        Re: I have a hard time understanding your post

        This useless flamebait.

        Brings me back top when I was 14.

  16. locster

    Finally and explaination

    I've experienced a lot of crashing of a Skylake i7 that is resistant to BIOS, driver and OS updates. My research lead me to several very long intel discussion forums of people experiencing similar crashing and not much help from Intel. So it's nice to see this is finally being acknowledged at least. Unfortunately the Asus m/board I have seems to not always puch a BIOS update when intel publish microcode updates/fixes, so it could still easily be well over a year before I get a fix (if at all). At least I have a potential working solution now (disable hyperthreading), previous suggestions (on the forums) have not worked, e.g. disabling the various CPU power management strategies has been one most discussed.

    1. patrickstar

      Re: Finally and explaination

      You can load microcode after boot as well, from your favorite OS. Linux has a tool for it that runs on boot - t Think it's included with Debian but the actual microcode isn't since it's a non-free binary blob.

      Windows has it as well and with some luck microcode updates arrive via Windows Update.

      Doing it at the BIOS/UEFI level is mostly needed when a bug/missing feature prevents the system from booting at all.

      1. Ramazan

        Re: when a bug/missing feature prevents the system from booting

        "I've seen things you people wouldn't believe".

  17. pugnaciousfool

    My Kaby Lake crashes in Ubuntu when the microcode is DISABLED

    I just did a Mini-STX build with a Pentium G4560 and notice that the system crashes regularly due to the integrated GPU if I don't enable the proprietary microcode. Guess I'm just damned if I do, damned if I don't at this point...

    1. cabdouch

      Re: My Kaby Lake crashes in Ubuntu when the microcode is DISABLED

      You should ALWAYS update the Microcode, running without any Microcode patches is really really bad.

      All processors are designed to have fixes applied as bugs are found, instead of having to "mask out" a new processor DIE each time, or slowing the process of releasing a new processor to 1 per decade.

      This is not a design flaw, it reduces costs if they can fix design flaws on the finished product after it is manufactured or even after it ships.

      Dozens of major and minor bugs have been fixed in the Microcode update prior to the first processor shipping, so running without these fixes is really really really bad.

      When a bug is found during the extensive testing phase, a Microcode fix is designed to resolve that problem. And while we could complain about this not being found earlier, it is usually the support community that finds these obscure hard-to-find bugs that feedback into the CPU company for fixes.

      Consider it the same as never updating a software package, even though known bugs are in it, without uninstalling the original software package and downloading and installing a whole new version.

      You would be asking why the software company didn't just release a patch to fix it.

  18. Jaap Aap

    Why wait for a bios update or perhaps a microcode update via windows update?

    With this VMWare thingy you can grab the latest microcode files from Intel (and AMD, otherwise the program may not work - not tested). This is installed as a driver, and in the event log you can see if a microcode update has been applied.

    Use these microcode files:

    Also works great for stuff with no bios update available.

  19. ad47uk

    I am glad i stayed

    with AMD, saying that the thought of changing to intel was only in my mind for a couple of hours and that was only when I was thinking of going from windows to a Mac.

    My Ryzen machine is running just fine

    1. cabdouch

      Re: I am glad i stayed

      AMD Processors have Microcode Updates released regularly as well.

      In fact, when I was designing AMD systems based on bleeding edge chips, like Ryzen, there might be two or three DOZEN Microcode updates after the CPU was released, and perhaps dozens to hundreds of patches already in the Microcode update.

      Every time we released a BIOS update for our AMD systems, we would get the latest Microcode update from AMD.

      All CPU manufacturers have Microcode updates and issues like Intel just had.

      Don't use this as a justification of the difference between Intel and AMD.

      I use the fact that AMD "Invents" technology, Intel "evolves" technology.

      The first brings us new cool stuff at much lower costs, which the second is safe and profitable.

      If Intel was smart, they would use AMD as an R&D house and use Intel's manufacturing capability to build them.

  20. Sil

    You conveniently forgot to convey that Intel discovered the bogue a long time ago, and began pushing its microcode fix to OEMs and system builders in April 2017.

  21. Anonymous Coward
    Anonymous Coward

    Layers upon layers upon layers

    It's amazing any of it works at all really.

    Java -> byte code -> JVM -> standard libs -> OS -> machine code -> microcode -> who knows what Intel has quietly jammed in below microcode - probably more Java.

  22. Anonymous South African Coward Silver badge

    Time to dump it all and revert back to the humble 80386/80387?

    1. Ian 55

      You mean the humble..

      .. 'couldn't even multiply two 16 bit numbers and get the right 32 bit result when first released 80386?'

      I had one of the '16 bit only'-stamped ones in an old PC. Windows 3.x was coded to watch out for them.

  23. cabdouch

    My Experience with this bug, Alternate Fix?, and BIOS Update

    I am working with Intel Support related to a bug I was able to reproduce repeatedly.

    They suggested changing Graphics Settings in the game that exhibits the problem.

    While this did help, eventually lock-ups and even a corrupted settings file began happening.

    Turning off "Turbo-Boost" appears to solve the problem

    Reading this article, I have now turned Turbo-Boost back on and turning off Hyper-Threading instead to see if this solves the problem as well.

    Since turning off Turbo-Boost seems to fix the problem, I am wondering if that is a better solution than turning off Hyper-Threading.

    According to the conditions that "should exist" for boosting to happen, it seems pretty rare that boosting "should" actually happen and losing half my processor threads seems like a bigger performance hit.

    Thoughts? (please not rants)

    1) Should turning off Turbo Boost also fix this problem? (doesn't seem like it would, but appears to in my case)

    2) Would you rather turn off Turbo Boost or Hyper-Threading to solve this problem?


    If you download the Intel BIOS File onto a USB Flash Key, then:

    1) You can update the BIOS in the built-in BIOS Setup utility by surfing to the Device and Directory the BIOS image file is in.

    2) Can do a "BIOS Recovery" by holding down the power buttom from the Off state for around 8 seconds (no longer, a LED color change usually signals the recovery) but the ONLY file that can be on the USB Flash key can be the BIOS Image file

    3) Use the motherboard vendors BIOS Update utility

    So for Linux users, there should be at least 2 update methods available without getting someone else to help you. But it is possible that the BIOS vendor or modifications specified by the motherboard vendor do not support these options.

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