includeos.org | Public website for includeos.org | Dataset library

by includeos JavaScript Version: Current License: MIT

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kandi X-RAY | includeos.org Summary

includeos.org is a JavaScript library typically used in Artificial Intelligence, Dataset, Jekyll applications. includeos.org has no bugs, it has no vulnerabilities, it has a Permissive License and it has low support. You can download it from GitHub.

Public website for includeos.org

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includeos.org has a low active ecosystem.

It has 8 star(s) with 11 fork(s). There are 2 watchers for this library.

It had no major release in the last 6 months.

There are 1 open issues and 1 have been closed. On average issues are closed in 175 days. There are no pull requests.

It has a neutral sentiment in the developer community.

The latest version of includeos.org is current.

Quality

includeos.org has no bugs reported.

Security

includeos.org has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

License

includeos.org is licensed under the MIT License. This license is Permissive.

Permissive licenses have the least restrictions, and you can use them in most projects.

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includeos.org releases are not available. You will need to build from source code and install.

Installation instructions, examples and code snippets are available.

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includeos.org Key Features

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includeos.org Examples and Code Snippets

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Community Discussions

Trending Discussions on includeos.org

How does KVM/QEMU and guest OS handles page fault

IncludeOS hello world failing

trying to understand delegates this code won't compile c++ 11

QUESTION

How does KVM/QEMU and guest OS handles page fault

Asked 2020-Mar-15 at 20:20

For example, I have a host OS (say, Ubuntu) with KVM enabled. I start a virtual machine with QEMU to run a guest OS (say, CentOS). It is said that to the host OS, this VM is just a process. So in the host's point of view, it handles page fault as usual (e.g., allocate page frame as needed, swap pages based on active/inactive lists if necessary).

Here is the question and my understanding. Within the guest OS, as it's still a full-fledged OS, I assume it still has all mechanisms handling virtual memory. It sees some virtualized physical memory provided by QEMU. By virtualized physical memory I mean the guest OS doesn't know it is in a VM, and still works as it would on a real physical machine, but what it has are indeed an abstraction given by QEMU. So even if a page frame is allocated to it, if that's not in guest's page table, the guest OS will still trigger a page fault and then map some page to the frame. What's worse, there may be a double page fault, where the guest first allocate some page frames upon page fault, which triggers page fault at host OS.

However, I also heard something like shallow (or shadow) page table which seems could optimize this unnecessary double page fault and double page table issue. I also looked at some other kernel implementation, specifically unikernels, e.g., OSv, IncludeOS, etc. I didn't find anything related to page fault and page table mechanisms. I did see some symbols like page_fault_handler but not as huge as what I saw in Linux kernel code. It seems memory management is not a big deal in these unikernel implementations. So I assume QEMU/KVM and some Intel's virtualization technologies have already handled that.

Any ideas in this topic? Or if you have some good references/papers/resources to this problem, or some hints would be very helpful.

...

ANSWER

Answered 2020-Mar-15 at 20:20

There are two ways for QEMU/KVM to support guest physical memory: EPT and shadow page tables. (EPT is an Intel-defined mechanism. Other processors support something similar, which I won't talk about here.)

EPT stands for Extended Page Tables. It is a second level of paging supported by the CPU in addition to the regular processor page tables. While running in a VM, the regular page tables are used to translate Guest Virtual Addresses into Guest Physical Addresses, while the EPT tables are used to translate Guest Physical Addresses into Host Physical Addresses. This double-level translation is performed for every memory access within the guest. (The processor TLBs hide most of the cost.) EPT tables are managed by the VMM while the regular page tables are managed by the guest. If a page is not present in the guest page tables, it causes a page fault within the guest, exactly as you have described. If a page is present in the guest page tables but not present in the EPT, it causes an EPT violation VM exit, so the VMM can handle the missing page.

Shadow page tables are used when EPT is not available. Shadow page tables are a copy of the guest page tables which incorporate both the GVA to GPA and GPA to HPA mappings within a single set of page tables. When a page fault occurs, it always causes a VM exit. The VMM checks whether the missing page is mapped in the guest page tables. If it is not, then the VMM injects the page fault into the guest for it to handle. If the page is mapped in the guest page tables, then the VMM handles the fault as it would for an EPT violation. Efficient management of shadow page tables across multiple processes within the guest can be very complex.

EPT is both simpler to implement and has far better performance for most workloads, because page faults are generated directly to the guest OS, which is generally where they need to be handled. The use of shadow page tables requires a VM exit for every page fault. However, shadow page tables may have better performance for a few specific workloads that cause very few page faults.

Source https://stackoverflow.com/questions/60694243

QUESTION

IncludeOS hello world failing

Asked 2019-Dec-02 at 23:31

I would like to look into IncludeOS and run their hello world. I am on Ubuntu and did install the required dependencies. The program exits with an error. What am I doing wrong here?

...

ANSWER

Answered 2019-Sep-26 at 21:27

After some work I found the answer: Hardware virtualization was disabled on my machine. I solved it by using this solution.

...such a stupid mistake!

Source https://stackoverflow.com/questions/58101236

QUESTION

trying to understand delegates this code won't compile c++ 11

Asked 2019-Jun-06 at 21:05

I was watching this video https://www.youtube.com/watch?v=QMb4RRFrY-o and am trying to follow the examples but i can't get the code to compile.

He supposedly copy and pasted the code from the link below but i also can't get it to compile.

I'm using QT to compile with visual studio 2015 x64 and c++11 enabled.

https://codereview.stackexchange.com/questions/14730/impossibly-fast-delegate-in-c11

Example 1

...

ANSWER

Answered 2019-Jun-06 at 21:05

You're compiling with C++11 but the code you're using requires C++14. I get a ton of errors when I compile with C++11, but they go away when I use C++14.

See here for an explanation of how to compile with C++14 in visual studio!

Why won't the code compile with C++11? The file "delegates.hpp" uses a lot of stuff in the C++14 standard library that doesn't appear in C++11.

For example, on line 76 of delegates.hpp, we see

Source https://stackoverflow.com/questions/56484859

Community Discussions, Code Snippets contain sources that include Stack Exchange Network

Vulnerabilities

No vulnerabilities reported

Install includeos.org

Git clone this repository, or download it into a directory of your choice. Inside the directory run.
bower install (reference: .bowerrc and bower.json)
npm install (reference: package.json)
bundle install (reference: Gemfile and Gemfile.lock)
composer install (optional, reference: composer.json and composer.lock)
Run npm start This will build your Jekyll site, give you file watching, browser synchronization, auto-rebuild, CSS injecting, Sass sourcemaps etc. The site will be built into the _dest folder.
Go to: http://127.0.0.1.xip.io:3000 Here you can access your site. If you want to access it with your phone or tablet, use the external access address which is showing up in the terminal window.
Go to: http://127.0.0.1.xip.io:3001 Here you can access the Browsersync UI.
You can also run make build to do this.
Run npm run build This builds your site for production, with minified CSS and JavaScript. Run this before you deploy your site!

Support

For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .

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