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Linux Fix Pending For Borked Hibernation After Disabling Hyper Threading

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  • Linux Fix Pending For Borked Hibernation After Disabling Hyper Threading

    Phoronix: Linux Fix Pending For Borked Hibernation After Disabling Hyper Threading

    If you have begun disabling Intel Hyper Threading on your systems over security concerns in light of MDS/Zombieload and other vulnerabilities making HT look increasingly unsafe, you may have noticed your system doesn't resume properly after hibernation. Fortunately, a fix is on the way...

    http://www.phoronix.com/scan.php?pag...e-HT-Hibernate

  • #2
    I get that a fix for this should be made because the option to turn of hyper threading in de OS exists, but shouldn't people disable this in the UEFI anyway?

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    • #3
      Originally posted by Jeroen View Post
      I get that a fix for this should be made because the option to turn of hyper threading in de OS exists, but shouldn't people disable this in the UEFI anyway?
      Disabling it in firmware/BIOS/UEFI is better, but surprisingly there's some OEMs that hide the option. From what I've seen, Acer laptops and desktops hide the setting. Most Dell/Alienware laptops show the setting though.

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      • #4
        Originally posted by Jeroen View Post
        I get that a fix for this should be made because the option to turn of hyper threading in de OS exists, but shouldn't people disable this in the UEFI anyway?
        yeah, all the stuff about SMT and HT and idle states is VERY MUCH better set at the UEFI/BIOS setup.

        So this bug is much less of an issue than it may look. Resume from a system where HT was disabled in board firmware isn't affected.

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        • #5
          Originally posted by Espionage724 View Post
          Disabling it in firmware/BIOS/UEFI is better, but surprisingly there's some OEMs that hide the option. From what I've seen, Acer laptops and desktops hide the setting. Most Dell/Alienware laptops show the setting though.
          Acer is a shit-grade brand though.

          Add to the list of the PCs that usually show the setting ASUS, HP and Lenovo. At least in the 700 and up price range. Low end models may suck.

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          • #6
            Originally posted by Espionage724 View Post
            Disabling it in firmware/BIOS/UEFI is better, but surprisingly there's some OEMs that hide the option. From what I've seen, Acer laptops and desktops hide the setting. Most Dell/Alienware laptops show the setting though.
            Aha, that explains. I have an Dell XPS 13 and a custom build mediaserver with an Asrock board, and both support turning it off in UEFI.

            Originally posted by starshipeleven View Post
            yeah, all the stuff about SMT and HT and idle states is VERY MUCH better set at the UEFI/BIOS setup.

            So this bug is much less of an issue than it may look. Resume from a system where HT was disabled in board firmware isn't affected.
            I never used hibernation anyway, it hasn't worked for me, ever.
            Something I also don't get: hibernation doesn't work with an encrypted swap partition, and most distribution when installing when you select the options "use LVM" and "encrypt drive" create one luks partition with lv1 root an lv2 swap. That means your swap partition is encrypted and hibernation doesn't work, right? Why even present the option in the menu (like GNOME and KDE do by default). The only thing selecting it will do is having to force a reset, possibly borking your system.

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            • #7
              Originally posted by Espionage724 View Post
              Disabling it in firmware/BIOS/UEFI is better, but surprisingly there's some OEMs that hide the option. From what I've seen, Acer laptops and desktops hide the setting. Most Dell/Alienware laptops show the setting though.
              In principle, yes. But even ignoring the fact some brands will hide the option, the real problem ultimately comes down to distribution. You can't tell the average person they need to disable it because most people have no clue what it is, let alone how to disable it. So unfortunately, that means the OS has to take care of it.

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              • #8
                Originally posted by starshipeleven View Post

                Acer is a shit-grade brand though.

                Add to the list of the PCs that usually show the setting ASUS, HP and Lenovo. At least in the 700 and up price range. Low end models may suck.
                In my small experience I have passed notebooks of all brands and claim that acer is a shitty brand does not make any sense. On the same notebook (low end), acer, asus, etc. does not change much, indeed .... acer from my experience is the one that gives less problems. For example, HP notebooks have the defect of heating up much more than others. In the new low-end bios uefi sometimes it is necessary to enable a password to access some settings.

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                • #9
                  Little rant about SMT and hibernation:
                  I don't see how this is even an issue. There are few scenario's I can think of where this would even have a chance of having an impact.
                  1. Desktops and laptops
                    1. By far the biggest impact of these CVE's are with multi-user systems. No need to disable SMT on a desktop or laptop, just take the performance hit of the mitigations and get on with your life. This way, you can still put your system in hibernation mode.
                  2. Servers
                    1. For people who have a server at home, most if not all motherboards for desktops/server have the option to disable SMT in the UEFI. If you don't have this option, you're using really old sh*t and don't have the option to use SMT anyway
                    2. For datacenters I can see disabling SMT in the UEFI is simply to much work, so you could want to do it on a OS level.
                    3. Both for both: I have never seen a server put into hibernation...
                  So yes, the option exists and therefore a fix should be make. But I don't see how anybody could possibly be impacted by this...
                  Last edited by Jeroen; 05-30-2019, 11:16 AM. Reason: Spell check

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                  • #10
                    Originally posted by Charlie68 View Post
                    In my small experience I have passed notebooks of all brands and claim that acer is a shitty brand does not make any sense. On the same notebook (low end), acer, asus, etc. does not change much, indeed ....
                    I'm not talking low-end stuff, I agree that they are mostly the same.
                    (although I've seen ASUS is usually better than most in the low-end)

                    I'm talking 700$ and higher price point laptops.
                    Acer isn't shit on 100% of their devices, but I've seen enough "doomed" model lines from them to blacklist the whole brand as crap. I can't wait a year and look at the support forums to see what is the shit and what is the usable hardware for a businness machine.

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