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who's post was edited? If they're referring to my original one, then there's only one possible edit I made, because I recall making a comment today that was mis

by olliej 3y ago

who's post was edited? If they're referring to my original one, then there's only one possible edit I made, because I recall making a comment today that was missing a word, but I updated that instantly so there were no comments or anything, or really likelihood anyone had read it prior to my comment. My "edit" that now has to be an additional comment is at https://news.ycombinator.com/item?id=39061507 https://news.ycombinator.com/item?id=39061507 - I'm curious if you agree with my justification on treating virtualization is meaning explicitly non-emulated these days. From your other comments it seems you do agree with me, but I'd like to know how you feel about the rationale. In response to the editing comment made, my rule for editing or changing comments is that if it's not an instantaneous edit, then the edit should be marked. In response to this thread (the whole thing, not just the one leading down these branches) I did write a stupidly long addendum but spent so long trying to find old marketing material I then couldn't make the edit \o/ My more careful rule about editing is that if someone has replied to a comment, I won't change the text that they replied to, unless the confusion is something very simple like a missing "not" or something where the original text was clearly wrong, and I'll generally do some variation of " .... [edit: not] ...". Otherwise I try to do it as adding additional text with a note saying the new text was added. I find silent edits incredibly annoying, as it means you can't tell if/what has changed in a comment you replied to, and it allows for people to exhibit some really screwed up behaviour. Basically along the same lines as people brought up when apple added editing/deleting to iMessage, where the original betas I think didn't show edits/deletion had occurred, nor what had been changed. I don't think it's reasonable in this day and age for sites like HN to not provide an edit history for comments.

dijit 3y ago
u/hnlmorg edited one of their comments in this chain I recognise right now. They said “you are just saying what I said” but now it has been altered to a much more agreeable and less aggressive statement. Shenanigans. nonetheless I believe it is yours that is being accused of being modified, and I do agree with you.
hnlmorg 3y ago
> I'm curious if you agree with my justification on treating virtualization is meaning explicitly non-emulated these days. I often see people try to make a distinction between hardware virtualisation and hardware emulation but the reality is they're just different sides of the same coin. It's like saying Typescript isn't a compiled language because it doesn't produce assembly like C would. Sometimes you need to emulate the entire CPU. Other times the guest and host CPUs are the same and that CPU supports hardware assisted virtualisation. But even AMD64 virtualisation solutions have to emulate some parts of the hardware stack (like the virtual network card) regardless of any paravirtalisation and other virt-extensions available by the CPU, GPU, and so on. To compound the confusing jargon. All emulators are a virtual machine but not all virtual machines are emulators. The distinction between containerisation and virtualisation is a lot easier to describe. Rather than placing hardware gaps (whether those hardware gaps are defined in software or hardware) like you do with virtualisation, instead you have all code running natively with only your kernel for protection. I guess you could draw some parallels between modern hypervisors and kernels, but even hear, you wouldn't run multiple kernels on top of each other in a container. However you would run multiple kernels on top of a hypervisor. The layer of separation is a lot different Personally I view the things as being 1. containerisation 2. virtualisation 2a. hardware assisted 2b. emulation ie emulation is a subset of virtualisation. Distinct in some ways but not an entirely new category in itself
- epcoa 3y ago
  This dichotomy of hardware assisted vs emulation is too simplistic though. > Sometimes you need to emulate the entire CPU. Other times the guest and host CPUs are the same and that CPU supports hardware assisted virtualisation. You don't need dedicated hardware assistance to do some amount of virtualization if you have an MMU and memory protection. This is how early VMware on x86 worked, it was not a full blown emulator, it did not need to emulate the entire CPU. Most guest code ran unaltered without emulation, only certain ring 0 code had to be emulated. VMware ESX and workstation ran usably well back in the x86 days, I mean it was a viable product. It was not just an "emulator", in contrast to something like BOCHS or early qemu. https://en.wikipedia.org/wiki/X86_virtualization https://en.wikipedia.org/wiki/X86_virtualization https://www.vmware.com/pdf/asplos235_adams.pdf https://www.vmware.com/pdf/asplos235_adams.pdf I don't think an accurate categorization really. Emulation is a technique that may be used in parts of the implementation for virtualization, but they're different concepts, one is not a subset of the other. > All emulators are a virtual machine No, I can emulate a single piece of hardware like a network adapter. I can emulate just a CPU core indepedent of a particular virtual environment.

by olliej 3y ago

dijit 3y ago

u/hnlmorg edited one of their comments in this chain I recognise right now. They said “you are just saying what I said” but now it has been altered to a much more agreeable and less aggressive statement. Shenanigans. nonetheless I believe it is yours that is being accused of being modified, and I do agree with you.

hnlmorg 3y ago

> I'm curious if you agree with my justification on treating virtualization is meaning explicitly non-emulated these days. I often see people try to make a distinction between hardware virtualisation and hardware emulation but the reality is they're just different sides of the same coin. It's like saying Typescript isn't a compiled language because it doesn't produce assembly like C would. Sometimes you need to emulate the entire CPU. Other times the guest and host CPUs are the same and that CPU supports hardware assisted virtualisation. But even AMD64 virtualisation solutions have to emulate some parts of the hardware stack (like the virtual network card) regardless of any paravirtalisation and other virt-extensions available by the CPU, GPU, and so on. To compound the confusing jargon. All emulators are a virtual machine but not all virtual machines are emulators. The distinction between containerisation and virtualisation is a lot easier to describe. Rather than placing hardware gaps (whether those hardware gaps are defined in software or hardware) like you do with virtualisation, instead you have all code running natively with only your kernel for protection. I guess you could draw some parallels between modern hypervisors and kernels, but even hear, you wouldn't run multiple kernels on top of each other in a container. However you would run multiple kernels on top of a hypervisor. The layer of separation is a lot different Personally I view the things as being 1. containerisation 2. virtualisation 2a. hardware assisted 2b. emulation ie emulation is a subset of virtualisation. Distinct in some ways but not an entirely new category in itself

epcoa 3y ago
This dichotomy of hardware assisted vs emulation is too simplistic though. > Sometimes you need to emulate the entire CPU. Other times the guest and host CPUs are the same and that CPU supports hardware assisted virtualisation. You don't need dedicated hardware assistance to do some amount of virtualization if you have an MMU and memory protection. This is how early VMware on x86 worked, it was not a full blown emulator, it did not need to emulate the entire CPU. Most guest code ran unaltered without emulation, only certain ring 0 code had to be emulated. VMware ESX and workstation ran usably well back in the x86 days, I mean it was a viable product. It was not just an "emulator", in contrast to something like BOCHS or early qemu. https://en.wikipedia.org/wiki/X86_virtualization https://en.wikipedia.org/wiki/X86_virtualization https://www.vmware.com/pdf/asplos235_adams.pdf https://www.vmware.com/pdf/asplos235_adams.pdf I don't think an accurate categorization really. Emulation is a technique that may be used in parts of the implementation for virtualization, but they're different concepts, one is not a subset of the other. > All emulators are a virtual machine No, I can emulate a single piece of hardware like a network adapter. I can emulate just a CPU core indepedent of a particular virtual environment.