How is the keyboard interrupt treated in a PC architecture? a. synchronous by the kernel and the apps b. synchronous by the kernel, async by the apps c. asynchronous

Explain your choice.

How is the implementation of Fast Userspace Mutex using the mechanisms provided by the virtual memory system?

What kind of problems does Read-Copy-Update solve and how?

Describe a method to prevent deadlocking.

Given a System Call Wrapper security mechanism, is it easier to exploit it on a single processor machine or on a dual processor one? Why and how can the exploit be written?

Explain what happens when executing the following C code in a process inside a UserModeLinux virtual machine: …
fprintf(File, “Operating Systems Practical”); …
Explain.

R: The tracing thread is intercepting and redirecting the process system call (write) into the virtual kernel.

What Xen module can be used to prevent attempts to connect to a Xen virtual machine on a specific port?

R: Xen provides a VRF in which each domain has one or more VIFs. Each VIF has 2 I/O rings for transmit and receive. Each direction has a list of associated rules (<pattern>, <action>). Domain0 is responsible for inserting and removing rules.

For a hypervisor in an energy-managed system, identify one of its features that is relevant for designing a host-level energy manager. Describe how the host-level energy manger can benefit from this feature.

Describe a scenario in which an end-host software error in the TCP segment would be generated.

R: ACK-of-FIN, Bad LF in CR/LF, Bad Hosts, or others

Which tainting mechanism(s) should be used for tracking down the effects of a malicious change of variable “p” in the following piece of code: int get_destination(int *p) { index = *p; x = locations[index]; return x; }

For a system with mobile devices accessing the same file-system simultaneously, which consistency model is best and why?