KFUPM also supplies students with privileged instruction
and training to make them able to contribute to comprehensive development after graduation, the rector said.
Underlying hardware mechanisms, such as the MMU, privileged instruction
access control (i.e.
Exception Level I (ELI), which executes an OS and anything else that executes privileged instructions
Because the binary translation of privileged instructions is so cumbersome, hardware-assisted virtualization has been added to modern x86 chips from Intel (Intel VT) and AMD (AMD-V).
Calls to privileged instructions are replaced with hypercalls handled by a special privileged guest VM (called Domain0 in Xen, or the root partition in Hyper-V).
To perform the emulation of privileged instructions, Disco additionally maintains the privileged registers and TLB contents of the virtual CPU in this structure.
Supervisor mode allows the operating system to use a protected portion of the address space (the supervisor segment), but does not give access to privileged instructions or physical memory.
To reduce this overhead, we patched the HAL of IRIX to convert these frequently used privileged instructions to use nontrapping load and store instructions to a special page of the address space that contains these registers.