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Linux To Begin Tightening Up Ability To Write To CPU MSRs From User-Space

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  • #11
    Originally posted by Danny3 View Post
    Sudo password is enough and if the want a kernel parameter they should do the reverse, allow by default setting the MSR with sudo and block it only if some kernel parameter is passed at boot.
    Sorry what? it should be safer by default, just like with a lot of other features.

    You should see the stuff I have to write in the kernel command line of my KVM virtualization server to allow PCIe passthrough. It's not a short list, but it's not a "safe" feature to leave on for everyone.

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    • #12
      Dell uses MSRs to throttle the CPUs in their laptops whenever someone plugs in an aftermarket charger or a charger that Dell thinks isn't powerful enough.

      By writing to MSRs, you can put the CPU back in it's normal power state, and not have to spend $130 on an OEM charging brick.

      Also, Linux will never replace Windows for gaming and hardware enthusiasts without the ability to overclock, undervolt or otherwise make changes to their computer. Linux already doesn't support this, so further tightening it down is going to hurt desktop adoption by a significant portion of users.

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      • #13
        The MSR has a utility available called msrtool that produces output similar to this (depending upon the CPU):
        http://samnoble.org/thinkpad/x60tabl...ot/msrtool.log
        http://samnoble.org/thinkpad/x61s_76663FU/msrtool.log

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        • #14
          Originally posted by birdie View Post
          Meanwhile Windows even in secure UEFI mode has no qualms allowing unfettered access to all CPU MSR registers.
          just as it allows any user to crap over disk c

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          • #15
            Intel CPUs can be undervolted for battery saving and it requires MSR access - so it is a very very bad patch. Hope it will be a way to reverse it.
            https://github.com/kitsunyan/intel-undervolt - that's the utility doing udervolting.

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            • #16
              Registers are the reason to choose Linux for developments.
              ​​​

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