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Yeah in theorem provers usually the opposite is true: "We want to put as little stuff as possible in the kernel because that's the part we need to verify by han
by lou1306 2mo ago
Yeah in theorem provers usually the opposite is true: "We want to put as little stuff as possible in the kernel because that's the part we need to verify by hand"
- eru 2mo agoIn an OS kernel that instinct is also true: 'we want to put as little as possible in the OS kernel, because that stuff can bring down the machine.'
- inigyou 2mo agoThat isn't true, as there are many things that can bring down the machine. If your X or Wayland server crashes, it brings down your machine.
- __s 2mo agoIt doesn't, it just loses your session
- inigyou 2mo agoA kernel panic doesn't bring down the CPU, nor the hard drive, or the RAM, or the power supply unit. So if we're being pedantic, the machine is still up.
- eru 2mo agoWell, a kernel bug gets write access to everything. A bug in userland is a bit more constrained in what it can do. That counts especially for accidental bugs and denial of service. To make a userland bug exploited adversarially not impact the rest of the system requires more hardening of the kernel.
- inigyou 2mo agoYeah a userland bug just gets all my passwords, SSH keys, personal secrets and whatever. Say it with me - there's no practical difference.
- eru 2mo agoYou are talking about a single user system. You can compartmentalise further. Modern processors even give you these 'rings' to help with the hardware side of that, if you want to.
- inigyou 2mo agoYes, these are the standard excuses. But has anyone actually thought about them in the last twenty years, in the context of the way we actually use computers?
- eru 2mo agoEh, yes? Just look the discussions surrounding the development of any web browser? Or look at the permissions system in Android or iOS or on Mac (and perhaps even Windows?).
- deleted 2mo ago[deleted]
- yjftsjthsd-h 2mo agoNo, that is true, even if not uniquely. A kernel bug can easily bring down the machine. Maybe Xorg can also manage it... although IMHO that also sounds like a kernel bug (surely it's the kernel's job to ensure no user program can do that?)... but that doesn't make the kernel safe. And I suspect it's easier to take down the machine from ring 0 than a display server even if both can do it.