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System Management Mode (SMM, sometimes called ring −2 in reference to protection rings) [1] [2] is an operating mode of x86 central processor units (CPUs) in which all normal execution, including the operating system, is suspended.
In computing, protected mode, also called protected virtual address mode, [1] is an operational mode of x86-compatible central processing units (CPUs). It allows system software to use features such as segmentation, virtual memory, paging and safe multi-tasking designed to increase an operating system's control over application software.
Although they are mutually incompatible, both Intel VT-x (codenamed "Vanderpool") and AMD-V (codenamed "Pacifica") allow a guest operating system to run Ring 0 operations natively without affecting other guests or the host OS. Before hardware-assisted virtualization, guest operating systems ran under ring 1. Any attempt that requires a higher ...
To implement memory ballooning, the virtual machine's kernel implements a "balloon driver" that allocates unused memory within the VM's address space into a pool of memory (the "balloon"), which makes that memory unavailable to other processes on that VM.
Process isolation can be implemented with virtual address space, where process A's address space is different from process B's address space – preventing A from writing onto B. Security is easier to enforce by disallowing inter-process memory access, in contrast with less secure architectures such as DOS in which any process can write to any ...
FIDO uses the concept of TEE in the restricted operating environment for TEEs based on hardware isolation. [13] Only trusted applications running in a TEE have access to the full power of a device's main processor, peripherals, and memory, while hardware isolation protects these from user-installed apps running in a main operating system.
Even drivers executing in user mode can crash a system if the device is erroneously programmed. These factors make it more difficult and dangerous to diagnose problems. [3] The task of writing drivers thus usually falls to software engineers or computer engineers who work for hardware-development companies. This is because they have better ...
An attempt to access unauthorized [a] memory results in a hardware fault, e.g., a segmentation fault, storage violation exception, generally causing abnormal termination of the offending process. Memory protection for computer security includes additional techniques such as address space layout randomization and executable-space protection.