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Global Descriptor Table. The Global Descriptor Table (GDT) is a data structure used by Intel x86 -family processors starting with the 80286 in order to define the characteristics of the various memory areas used during program execution, including the base address, the size, and access privileges like executability and writability.
There are two such tables, the Global Descriptor Table (GDT) and the Local Descriptor Table (LDT), each holding up to 8192 segment descriptors, each segment giving access to 64 KB of memory. In the 80286, a segment descriptor provides a 24-bit base address , and this base address is added to a 16-bit offset to create an absolute address.
This allows operating systems to use these segments for special purposes. Unlike the global descriptor table mechanism used by legacy modes, the base address of these segments is stored in a model-specific register. The x86-64 architecture further provides the special SWAPGS instruction, which allows swapping the kernel mode and user mode base ...
Load GDTR (Global Descriptor Table Register) from memory. [b] Yes 0 LIDT m16&32 [a] 0F 01 /3: Load IDTR (Interrupt Descriptor Table Register) from memory. [b] The IDTR controls not just the address/size of the IDT (interrupt Descriptor Table) in protected mode, but the IVT (Interrupt Vector Table) in real mode as well. LMSW r/m16: 0F 01 /6
Interrupt descriptor table. The interrupt descriptor table (IDT) is a data structure used by the x86 architecture to implement an interrupt vector table. The IDT is used by the processor to determine the memory addresses of the handlers to be executed on interrupts and exceptions. The details in the description below apply specifically to the ...
Contents. List of x86 virtualization instructions. Instruction set extensions that have been added to the x86 instruction set in order to support hardware virtualization. These extensions provide instructions for entering and leaving a virtualized execution context and for loading virtual-machine control structures (VMCSs), which hold the state ...
A segment descriptor may limit access rights, e.g., read only, only from certain rings. The x86 architecture has multiple segmentation features, which are helpful for using protected memory on this architecture. [1] On the x86 architecture, the Global Descriptor Table and Local Descriptor Tables can be used to reference segments in the computer ...
x86 assembly language is the name for the family of assembly languages which provide some level of backward compatibility with CPUs back to the Intel 8008 microprocessor, which was launched in April 1972. It is used to produce object code for the x86 class of processors. Regarded as a programming language, assembly is machine-specific and low ...