README
¶
NAME
segment - segmented address translation
DESCRIPTION
At the very minimum, virtual address space consists of code, stack and heap, where stack and heap oftentimes grow in opposite directions due to dynamic growth.
Segments allow to map each of the above blocks inpedently onto physical address space at different locations, leading to better utilization of the physical mmemory, reduced fragmentation, easy relocation to grow segments, or even share segments between processes, e.g. code segment.
A segment is described by:
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base: the location of the segment in physical address space.
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bounds: size of the segment.
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direction: direction of growth (heap and stack grow in opposite directions).
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offset: offset of the segment in virtual address space. Code segment typically starts at 0B, then goes heap, and stack grows from the end of the virtual address space.
A virtual address is the memory location in the virtual address space. It also includes the segment number to perform an address translation.
EXAMPLE
% segment -segA 2:2 -segB 4:2
configuration:
virtual address bounds: 4KB
SEG0 base: 2KB bounds: 2KB dir: positive virt-base: 0KB
SEG1 base: 4KB bounds: 2KB dir: negative virt-base: 4KB
translations
virt: 3462 (SEG1) phys: 5510
virt: 3046 (SEG0) segmentation fault
virt: 2484 (SEG0) segmentation fault
virt: 2949 (SEG0) segmentation fault
virt: 342 (SEG0) phys: 2390
Documentation
¶
Overview ¶
Segment demonstrates address translation with support for memory segments.
SYNOPSIS ¶
segment [-n num] [-segA base:bounds] [-segB base:bounds] [-vm-bounds num]
DESCRIPTION ¶
A memory segment is a logical block of virtual memory. It has own base and bounds settings, along with permission bits (rwx), direction (positive or negative offset).
Segment tool uses multiple segments to run address translation of virtual to physical address, referenced within different segments.
EXAMPLE
% segment -segA 2:2 -segB 4:2 configuration: virtual address bounds: 4KB SEG0 base: 2KB bounds: 2KB dir: positive virt-base: 0KB SEG1 base: 4KB bounds: 2KB dir: negative virt-base: 4KB translations: virt: 3462 (SEG1) phys: 5510 virt: 3046 (SEG0) segmentation fault virt: 2484 (SEG0) segmentation fault virt: 2949 (SEG0) segmentation fault virt: 342 (SEG0) phys: 2390
Source Files
Directories
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| Path | Synopsis |
|---|---|
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internal
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mem
Package mem provide basic primites to emulate memory management.
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Package mem provide basic primites to emulate memory management. |
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report
Package report provides primitives to generate a simulation report.
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Package report provides primitives to generate a simulation report. |