MP 1,1-5,1 MP5,1: BootROM thread | is a pre-requisite to disable Hyper-threading

Discussion in 'Mac Pro' started by tsialex, Aug 13, 2018.

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  1. cheezegrate macrumors newbie

    May 15, 2019
    Same here. You sure about that? HT might not even be the best idea if you need to rely on those threads. Give it a try.

  2. AidenShaw, May 17, 2019
    Last edited: May 17, 2019

    AidenShaw macrumors P6


    Feb 8, 2003
    The Peninsula
    One of the first things that I do when I get a new system is to disable hyperthreading - and I've done this since when HT first appeared.

    On a case-by-case basis, I may enable hyperthreading. Those cases are when the system spends significant time with all physical cores busy. If you don't have significant periods of time with 100% CPU usage, hyperthreading can hurt your performance. Even if you do hit over 100%, hyperthreading is often only a mild benefit.

    On Linux you can dynamically enable/disable logical CPUs by writing to the /sys filesystem.

    echo 0 > /sys/devices/system/cpu/cpu113/online​

    will instantly remove logical CPU 113 from the system. The command

    echo 1 > /sys/devices/system/cpu/cpu113/online​

    will put logical CPU 113 back online.

    On a typical Linux system the "htop" command will show core usage. For example, it may show:

    (For some reason, "htop" numbers CPUs from 1 to N, whereas most tools number them from 0 to N-1.)

    In this screenshot, CPUs 1 to 72 are the "physical" cores, and CPUs 73 to 144 are the HT "second class" cores. (Core 73 is sharing core 1 resources.) If you iterate the command

    echo 0 > /sys/devices/system/cpu/cpu$idx/online​

    from $idx=72 to $idx=143 - you'll instantly disable hyperthreading (until the next boot). Write a "1", and instantly the logical core is back.

    I've tested quite a few workloads with and without HT using this technique - and HT is seldom a big win.

    Also note that different systems enumerate cores differently. I think that Windows puts logical core 0 and logical core 1 on the same physical core (and logical core 142 and logical core 143 on the same physical core).
  3. Demigod Mac macrumors 6502a

    Apr 25, 2008
    Don't forget you actually have to get hit with a payload for the vulnerability to matter. For that to happen you have to be exposed to malicious code, like being tricked into opening a trojan or visiting a website with an attack script. This isn't a new, innovative way for malicious code to be delivered to a machine, just a new thing malicious code can do once it's been downloaded and executed. Reading news reports on these vulnerabilities makes it sound like a hacker just needs to sneeze at your machine to break in, which isn't necessarily true.
    • Is your web browser up to date?
    • Do you have an adblocker extension installed? (to prevent malvertising attacks)
    • Xprotect definitions up to date?
    • Is your Mac behind a router with a firewall?
    • Do you avoid visiting shady websites?
    • Do you carefully vet the source of the software you download?
    You'll probably be fine, then. Install NoScript if you're still paranoid. Internet street-smarts should be your front-line defense. If you get hit with an attack but have HT disabled, guess what - you still have a problem because malicious code is still running on your machine.
  4. handheldgames macrumors 68000


    Apr 4, 2009
    Pacific NW, USA
    FWIW... I have about 0% chance of disabling hyper-threading. Safari and chrome have both patched for zombieload. The 4,1/5,1 is slow enough... Disabling hyper-threading? I might as well recycle the aluminum chassis.
  5. Mac_User 0101 macrumors regular

    Oct 8, 2017
    That is really interesting and you have me looking at this different now. A lot of my software and particularly plugins utilize distributed processing across multiple cores. I'll have to try disabling HT while running a large session with a lot of plugins and see if it's the same CPU performance if not better.
    --- Post Merged, May 17, 2019 ---
    Actually, what worried me most was the vulnerability was demonstrated attacking a computer running the current version of TOR browser within a VM instance of Tails. Just goes to show with the right set of skills a hacker will achieve their payload regardless of most basic security implementations. I guess these Intel processors are just RIDL'd with security holes:p
  6. Demigod Mac macrumors 6502a

    Apr 25, 2008
    I think that was a bit of dramatic flair on the researchers' part. If something as low level as the CPU is compromised then it doesn't matter if the target is Notepad.exe or a TOR browser running in a VM. But once again, in order to pull off that neat trick the attacker needs to successfully circumnavigate multiple layers of security and hit your machine with a payload that exploits the vulnerability, not to mention consider you a worthwhile target for all the effort. Entities that should be worried about this would include governments, large corporations and data centers - the most likely targets for a sophisticated information espionage attack.

    To conclude, disabling hyperthreading on a Mac used in a home or small business seems really unnecessary if you follow basic internet security practices.
  7. cheezegrate macrumors newbie

    May 15, 2019
    That's what I was trying to get at. But as always: YMMV
    You can change that in the settings.

    Are we getting too off-topic here...?

  8. yager macrumors newbie


    May 18, 2019
    Could be wrong, but I cannot see Intel staying the course and refusing to update the microcodes for the X56 proc regardless what they put in print. Why, this was one of the main procs in the HP 360/380 line for the 5520 chipset in the G7s. There are a lot of G7s out there in data centers all over the world still running and still under extended warranty by HP. Yes, you would be surprised. Unless Intel is willing to assist HP and not Apple. There would be too much blowback coming out of this vulnerability and Intel sitting on their hands. Maybe Intel seen Apple had so much fun on their planned obsolescence class action suite, Intel wanted to get in some of that action too.
  9. tsialex thread starter macrumors 601


    Jun 13, 2016
    I hope that I'm wrong, but I'm inclined to think that Intel announced that they don't plan to issue microcode corrections for Nehalem and Westmere Xeons to force enterprise upgrades for servers with these processors still in use.

    Intel will get a lot of enterprise blowback and probably some from angry workstation users, that they effectively don't care, but a lot of CTOs will think that's the time of upgrading anything Nehalem/Westmere anyway and thats the push they need to justify spending the money.

    The financial gains will be more than the blowback and thats what Intel wants. They care zilt for Mac Pro users.

    Now let's go back to the usual BootROM topics.
  10. flehman macrumors 6502


    Feb 21, 2015
    In case this info is helpful to anyone. I am on a 4,1->5,1 with a MVC-flashed GTX 980 and still on HS 10.13.6 due to lack of drivers for Mojave. I was still able to download the Mojave full installer and run the 144 BootROM upgrade. I guess the installer doesn’t check the GPU too closely during the BootROM upgrade.
  11. h9826790, May 19, 2019
    Last edited: May 19, 2019

    h9826790 macrumors G5


    Apr 3, 2014
    Hong Kong
    It checked your GPU. 980 is a Metal supported GPU. You can check your system info.

    In HS, when web driver is loaded, Metal is available. That’s why Mojave installer can trigger the firmware update.

    If you make a Mojave USB installer (or even simply disable web driver in HS), and use the Mac EFI UGA Display ability to run the installer. There will be no Metal support GPU detected, and the firmware update won’t be triggered.

    It’s a matter of if web driver / Metal available in your current OS, not Mojave.
  12. flowrider macrumors 603


    Nov 23, 2012
    Thanks for your post, but it's posted in the wrong thread. Many of use have done what you describe, it's detailed in this thread:

    Personally I am running an MVC flashed GTX 1080 in 10.13.6 (17G7024).

  13. macsforme macrumors regular

    Mar 16, 2007
    FWIW, with the 144 firmware and the NVRAM settings to disable HyperThreading, my Windows 10 UEFI installation (yes I know, I know) is unstable. It intermittently freezes on the Windows logo at the beginning of the boot sequence, before the spinning wheel, and goes no further. When it does boot successfully, it shows HyperThreading disabled, as others have pointed out. If I reset the NVRAM to clear out those settings, Windows goes back to being stable again.

    I’m not sure if reinstalling Windows with those NVRAM settings in effect would help, but I just reinstalled Windows for other reasons so I’m not super keen on doing that. I’m also afraid to mess with it too much more, since I think it’s freezing right around when the SecureBoot/certificate stuff happens, and I know that is already a known problem area for these machines...
  14. trifero macrumors 6502

    May 21, 2009
    Good to know. Thnx.
  15. mrtang42 macrumors member

    Apr 19, 2019
    FYI, my legacy mode win 10 1809 runs flawless after I disabled the HT.
  16. trifero macrumors 6502

    May 21, 2009
    I´m curious about How many users ara disabling HT. In my case, not a chance.
  17. bookemdano macrumors 65816

    Jul 29, 2011
    Not for me right now as I'm doing a bunch of Handbrake encoding. Perhaps I will when I'm done with that project.
  18. Spacedust macrumors 6502a

    May 24, 2009
    Also not for me. This is just crazyness! It's like buying a Ferrari then limiting it to 100 km/h for safety reasons.
  19. Norbert Mikołajczyk macrumors regular

    Norbert Mikołajczyk

    May 26, 2016
    intel give me a discount on new Mac Pro or just do what you need to do and patch the cpus!!!
    I'm so angry at them that I really can't imagine to buy new pricey Mac Pro with cpus from them.
    I would rather switch to amd.
    My current beefed Mac Pro is doing just fine and the new AMD VII GPU will expand its possibilities even more with hardware H265 support.
  20. crjackson2134 macrumors 601


    Mar 6, 2013
    Charlotte, NC
  21. trifero macrumors 6502

    May 21, 2009
  22. tsialex thread starter macrumors 601


    Jun 13, 2016
    Today @orph sent his mid-2010 dump to check, his Mac Pro can't boot W10 anymore. His NVRAM is a mess and I had to improve my signature file to just to parse the dump.:eek:
    • Multi MemoryConfigs, 25 entries.
    • 12 PanicInfoLogs (Kernel Panics) with a different format than what I usually found in previous dumps
    • 2 IASInstallPhaseList logs,
    • 3 IASCurrentInstallPhaseBoot logs.
    Screen Shot 2019-05-20 at 14.22.23.png

    Signature version 8:
    • corrects the start of 1st and 2nd NVRAM stream,
    • implements logic checks to detect and show 11 and 12-digits SSN,
    • implements logic checks to detect and show 3 and 4 digits HWC,
    • correctly detects the second format for Kernel Panics, calling it B for now.
    Some more improvements and I can release it publicly or send a patch for binwalk, still have to decide what's best.
  23. tsialex, May 20, 2019
    Last edited: May 20, 2019

    tsialex thread starter macrumors 601


    Jun 13, 2016
    Today Apple re-issued:
    • 10.14.5 combo/delta,
    • Security Update 2019-003 for 10.12.6,
    • Security Update 2019-003 for 10.13.6
    • iTunes Device Support
    All of last week non-beta releases were deprecated. Reissues have the same builds as last week:
    • 18F132 build for 10.14.5
    • 17G7024 for Security Update 2019-003 for 10.13.6
    • 16G2016 for Security Update 2019-003 for 10.12.6
    Screen Shot 2019-05-20 at 22.19.23.png
    --- Post Merged, May 20, 2019 ---
    No firmware changes, btw.
  24. Earl Urley macrumors 6502

    Earl Urley

    Nov 10, 2014
    The Mojave installer on the App Store hasn't been updated, it's still at updated "1 wk ago"
  25. TheStork macrumors 6502


    Dec 28, 2008
    Does this mean we should manually download the updated updates and re-install them? Are the build numbers different on the newer updates?
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