Advanced Operating Systems

This is the home page for the "Advanced OS" course. Here, you will find (in a badly-organised form) all the material, slides, and information needed to attend the course

For the previous editions of the course, check the old websites (2018, 2019, and 2020).

Lessons:

• First lesson: 2022/11/03, White room, 9:00 -> 11:00
  • Introduction to the course
  • Introduction to real-time operating systems
• Second lesson: 2022/11/10, PC room, 9:00 -> 11:00
  • On Real-Time Operating Systems, again
  • Quick summary about computer architectures and Operating Systems
• Third lesson: 2022/11/17, PC room, 9:00 -> 11:00
  • On kernel latencies, again
  • OS kernel architectures for real-time
• Fourth lesson: 2022/11/24, White room, 9:00 -> 11:00
  • OS kernel architectures for real-time, again
  • Something more on uKernels vs dual-kernels
  • Summing up: modelling kernel latency as a blocking time
• Fifth lesson: 2022/12/01, White room, 9:00 -> 11:00
  • Fully preemptable real-time kernels (using PI to have real-time performance in user space)
  • Implementing periodic tasks
  • Example with Xenomai
• Sixth lesson: 2022/12/06, White room, 9:00 -> 11:00
  • Something more on uKernels...
  • ...and on nanoKernels
  • Some experiments with uKernels (l4re)
• Seventh lesson: 2022/12/15, White room, 9:00 -> 11:00
  • From nanokernels to hypervisors and back to uKernels
• Eighth lesson: 2022/12/22, White room, 9:00 -> 11:00
  • Page table virtualization
  • Some practical examples with trap'n'emulate
• Nineth lesson: 2023/01/12, 9:00 -> 11:00
  • Introduction to hardware assisted virtualization
  • Examples about VT-x and KVM
• Tenth lesson: 2023/01/19, 9:00 -> 11:00
  • Virtualizing I/O (simple example with KVM)
  • Discussion about virtualized I/O in hosted and bare-metal hypervisors (VMM and DM)
  • Something about unikernels
  • Something about real-time VMs

Project Ideas

Here are some ideas for possible projects for the exam. Remember to contact me when you chose one.

References:

• List of references to scientific papers
• Some standards about executable formats (useful to implement a loader / ELF parser in a hypervisor or microkernel)
• The Intel CPU manuals, useful to implement bare-metal hypervisors, kernels, and to use Intel's hardware-assisted virtualization technologies

Examples:

• Examples about periodic timers
• Some tests with Xenomai
• Example about using l4re. Follow these instructions to use it.
• Very simple example about trap and emulate, also showing an issue with the x86 ISA not respecting Popek & Goldberg requirements (the instruction to read the "Machine Status Word" register is sensitive but not privileged)
  • Same example, with the guest code separated in a different executable file (as a reference, see how GRUB loads Xen and its Dom0 kernel or how l4re loads its servers)
  • Same example again, this time parsing the ELF format of the guest to load it. Notice how this bare-metal hypervisor has to implement memory management and other functionalities needed by the ELF parser
• Simple example about using Intel's VT-x (as a hosted hypervisor or as a bare-metal hypervisor)
  • Execution of the hosted hypervisor
  • Execution of the bare-metal hypervisor
• Example with KVM
  • Small improvement of the KVM example, separating the guest code in a different executable
  • Patch showing how to handle I/O

Useful Links:

• The Linux kernel
• The Preempt-RT patchset
  • Notes about developing real-time applications
• Dual-kernel systems: Xenomai, EVL, RTAI
• Microkernels: l4re, sel4, Genode, GNU Hurd (based on Mach), Google Zircon (note: "handles" are similar to capabilities), ...
• Hypervisors: Xen, ACRN, Jailhouse, ...
• Some lightweight VMs / VMMs using KVM (see also QEMU's microvm): the Intel cloud hypervisor, Amazon's FireCracker, ...
  • To see a reference simple VMM based on KVM, check TinyEMU or kvmtool
• The Rump Kernels, useful for example to build unikernels based on openbsd source code. Notice that the rumpkernel.org site seems to be down