Re: [seL4] Some questions about seL4 operating system

Dear Professor Heiser, I have read the eurosys paper you recommended, I think it is a good idea to leverage a reliable second os to handle disk write requests. I am curious about the following questions, 1 How could the virtulization overhead achieve only 9%, according to the report, KVM (theoretically faster?) would cause 20% - 30% overhead for io intensive workloads 2 Does the user space VMM open source? 3 What is the device model of the VMM, take the virtual disk in this paper as an example, is it to some extent, like the device model in XEN? The VD driver in guest os sends the requests to VMM, VMM does the hard work to write the data into physical disk? If the understanding is correct, then VMM must implement the real device driver? For XEN, it could leverage the os in domain 0 to avoid reimplement device drivers. So in a word, is it necessary to rewrite device driver for seL4 or there are some ways to leverage legacy drivers by passthrough something? Cheers, Li Wang At 2015-07-16 19:50:24, "Gernot Heiser" wrote:

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On 16 Jul 2015, at 21:22 , Qing Wei wrote:

Hi, I am a beginner to seL4 as well as microkernel, and very interested in it. I think it is great in terms of its minimality and formally verified security. However, I have some questions about it, (1) How is its performance compared to other monolithic kernel, say, Linux. Could it make use of multicore, multiprocessor to enjoy the performance scalability? (2) How is its ecosystem, fox example, how to support new hardware, does it need write the driver from scratch or could it make use of Linux driver? And how to write application on it, or, could it run Linux application without modification? (3) How is its virtualization support, could it run Linux vm, and does it need any modification to the guest os?

For general microkernel and L4 introduction, I recommend - wikipedia, try “microkernel” and “L4 microkernel family”. - the FAQ on sel4.systems - our Advanced OS course: https://www.cse.unsw.edu.au/~cs9242/current/

You’ll find answers to most of your more specific questions in this paper: https://ssrg.nicta.com.au/publications/nictaabstracts/Heiser_SDBSA_13.abstra...

Re multicore, you’ll find more in this paper (only abstract for now, the PDF will go up next week): https://ssrg.nicta.com.au/publications/nictaabstracts/Peters_DEH_15.abstract...

Gernot

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