Handptright limit specifies the length of the segment

Info icon This preview shows pages 45–54. Sign up to view the full content.

View Full Document Right Arrow Icon
handptright limit – specifies the length of the segment. square6 Segment-table base register (STBR) points to the segment table’s location in memory. square6 Segment-table length register (STLR) indicates number of segments used by a program; segment number s is legal if s < STLR.
Image of page 45

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Silberschatz, Galvin and Gagne 2002 9.46 Operating System Concepts Segmentation Architecture (Cont.) square6 Relocation. handptright dynamic handptright by segment table square6 Sharing. handptright shared segments handptright same segment number square6 Allocation. handptright first fit/best fit handptright external fragmentation
Image of page 46
Silberschatz, Galvin and Gagne 2002 9.47 Operating System Concepts Segmentation Architecture (Cont.) square6 Protection. With each entry in segment table associate: handptright validation bit = 0 illegal segment handptright read/write/execute privileges square6 Protection bits associated with segments; code sharing occurs at segment level. square6 Since segments vary in length, memory allocation is a dynamic storage-allocation problem. square6 A segmentation example is shown in the following diagram
Image of page 47

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Silberschatz, Galvin and Gagne 2002 9.48 Operating System Concepts Segmentation Hardware
Image of page 48
Silberschatz, Galvin and Gagne 2002 9.49 Operating System Concepts Example of Segmentation
Image of page 49

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Silberschatz, Galvin and Gagne 2002 9.50 Operating System Concepts Sharing of Segments
Image of page 50
Silberschatz, Galvin and Gagne 2002 9.51 Operating System Concepts Segmentation with Paging – MULTICS square6 The MULTICS system solved problems of external fragmentation and lengthy search times by paging the segments. square6 Solution differs from pure segmentation in that the segment-table entry contains not the base address of the segment, but rather the base address of a page table for this segment.
Image of page 51

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Silberschatz, Galvin and Gagne 2002 9.52 Operating System Concepts MULTICS Address Translation Scheme
Image of page 52
Silberschatz, Galvin and Gagne 2002 9.53 Operating System Concepts Segmentation with Paging – Intel 386 square6
Image of page 53

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Silberschatz, Galvin and Gagne 2002
Image of page 54
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern