Global Descriptor Table: Difference between revisions
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Change flag names to be more in line with the intel manual.
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Revolution (talk | contribs) (Added section to make clear that the format of system segments is different from usual segments.) |
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* '''S:''' Descriptor type bit. If clear ('''0''') the descriptor defines a system segment (eg. a [[Task_State_Segment|Task State Segment]]). If set ('''1''') it defines a code or data segment.
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* '''DC:''' Direction bit/Conforming bit.
** For data selectors: Direction bit. If clear ('''0''') the segment grows up. If set ('''1''') the segment [[Expand_Down|grows down]], ie. the '''Offset''' has to be greater than the '''Limit'''.
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** For code segments: Readable bit. If clear ('''0'''), read access for this segment is not allowed. If set ('''1''') read access is allowed. Write access is never allowed for code segments.
** For data segments: Writeable bit. If clear ('''0'''), write access for this segment is not allowed. If set ('''1''') write access is allowed. Read access is always allowed for data segments.
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* '''L:''' Long-mode code flag. If set ('''1'''), the descriptor defines a 64-bit code segment. When set, '''Sz''' should always be clear. For any other type of segment (other code types or any data segment), it should be clear ('''0''').
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