Question to Torvalds

By: Etienne Lorrain (, January 14, 2021 3:02 am
Room: Moderated Discussions
Jörn Engel ( on January 13, 2021 8:49 am wrote:
> Maynard Handley ( on January 9, 2021 3:12 pm wrote:
> >
> > I ask this seriously: what does achieving raw metal linux achieve over VM linux?
> Maynard has demonstrated multiple times that he doesn't want to learn,
> but to argue. So this answer is explicitly for everyone else. ;)
> It is almost always about control.
> - I regularly see seconds of latency for high-priority realtime threads in VMs. I used to
> see similar problems on bare metal - until I fixed the bugs. Fixing hypervisor bugs in a
> Linux hypervisor is already too painful to consider, with OSX it is plain impossible.
> - There is no NMI timer interrupt, but you can simulate one by using performance counters. But inside
> a VM those counters don't work, so your interrupt only fires if you force the VM to burn CPU.
> - Every hypervisor intercepts some keys. I've had to crawl through menus with a mouse to piece
> together sysrq-something or ctrl-alt-del. Bare metal simply doesn't annoy you in such ways.
> - If you want to use the entire system, particularly all of RAM, the hypervisor will
> get in the way. You can pin two threads to two different CPUs inside the VM, but the
> hypervisor is still allowed to schedule those threads on the same physical CPU. Swap
> will happen in ways you cannot control. The entire VM may get killed without warning.

And another problem with Virtual Managers (but this one not only on Macs):
You might want to check your whole DRAM for failing bits, for instance using memtest under BIOS, and having a virtual (i386 real-mode) machine created by the EFI BIOS (with maximum 4 Gbytes of DRAM) will lead to a "memory error" or crash when attempting to check the DRAM at address 0x1_0000_0000...
I suppose someone will say that Macs have a perfect DRAM and never develop any randomly failing bit.
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Question to TorvaldsPaul2020/11/14 04:08 AM
  Question to TorvaldsLinus Torvalds2020/11/14 02:12 PM
    Question to Torvaldsnever_released2020/11/14 05:12 PM
      Question to TorvaldsDoug S2020/11/15 09:55 AM
        Question to Torvaldsnever_released2020/11/15 12:31 PM
          Question to TorvaldsDoug S2020/11/16 10:46 AM
            Question to TorvaldsMaxwell2020/11/16 11:49 AM
              Question to Torvaldsnever_released2020/11/16 04:25 PM
                Question to Torvaldslyra642020/11/23 11:23 AM
    Question to Torvaldsme2020/11/22 12:11 PM
    Question to TorvaldsJames2020/11/25 06:59 AM
    Question to Torvaldsbakk2021/01/09 03:35 PM
      Question to TorvaldsMaynard Handley2021/01/09 04:12 PM
        He asked disingenuously (NT)JS2021/01/09 08:33 PM
          He asked disingenuouslyMaynard Handley2021/01/10 10:51 AM
            He asked disingenuouslyJS2021/01/10 03:50 PM
              He asked disingenuouslyMaynard Handley2021/01/10 06:02 PM
        Question to Torvaldsanon2021/01/10 07:01 PM
          Question to TorvaldsMaynard Handley2021/01/10 07:59 PM
            Question to Torvaldsanon2021/01/11 09:56 AM
              Question to TorvaldsJukka Larja2021/01/12 05:50 AM
        Question to Torvaldsanon22021/01/10 07:21 PM
          Question to TorvaldsMaynard Handley2021/01/10 08:15 PM
            Question to TorvaldsMaynard Handley2021/01/10 08:22 PM
            Question to Torvaldsanon22021/01/10 08:47 PM
              Question to TorvaldsMaynard Handley2021/01/10 09:28 PM
                Question to Torvaldsanon22021/01/10 10:36 PM
        Question to TorvaldsJukka Larja2021/01/11 06:21 AM
          Question to TorvaldsMaynard Handley2021/01/11 10:33 AM
            Question to Torvaldsanon22021/01/11 10:40 PM
            Question to TorvaldsJukka Larja2021/01/12 06:05 AM
              Question to TorvaldsMaynard Handley2021/01/12 09:42 AM
                Question to TorvaldsJukka Larja2021/01/12 11:15 AM
                  Question to TorvaldsMaynard Handley2021/01/12 12:07 PM
                    Question to TorvaldsJukka Larja2021/01/13 06:24 AM
                      Question to TorvaldsMichael S2021/01/13 08:45 AM
                    Question to TorvaldsUngo2021/01/13 07:34 PM
        Question to TorvaldsJörn Engel2021/01/13 09:49 AM
          Question to TorvaldsEtienne Lorrain2021/01/14 03:02 AM
            Question to Torvaldsdmcq2021/01/14 08:26 AM
              Question to TorvaldsJörn Engel2021/01/14 11:42 AM
                Question to Torvaldsdmcq2021/01/14 12:13 PM
                  Question to TorvaldsJukka Larja2021/01/15 06:57 AM
                    Question to Torvaldsdmcq2021/01/15 08:27 AM
                      Question to TorvaldsAnne O. Nymous2021/01/15 12:19 PM
                        Question to Torvaldsdmcq2021/01/15 02:58 PM
                          Question to TorvaldsJukka Larja2021/01/15 09:04 PM
                            Question to Torvaldsdmcq2021/01/16 02:50 AM
                              Question to TorvaldsJukka Larja2021/01/16 09:37 PM
                                Question to Torvaldsdmcq2021/01/17 06:39 AM
                                  Question to TorvaldsAdrian2021/01/17 08:46 AM
                                    Question to Torvaldsdmcq2021/01/17 09:36 AM
                                  Question to TorvaldsJukka Larja2021/01/17 09:35 AM
                                    Question to Torvaldsdmcq2021/01/17 10:01 AM
                                      Question to TorvaldsJukka Larja2021/01/17 10:52 AM
            Question to TorvaldsDoug S2021/01/14 10:37 AM
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