Time - University of Cambridge · 2003. 9. 7. · f ) ) ±) >))) ) & [ # \3] ) / :< /):;)) ^)) $ $...

18
Operating System Hardware App 2 App N App 1

Transcript of Time - University of Cambridge · 2003. 9. 7. · f ) ) ±) >))) ) & [ # \3] ) / :< /):;)) ^)) $ $...

Page 1: Time - University of Cambridge · 2003. 9. 7. · f ) ) ±) >))) ) & [ # \3] ) / :< /):;)) ^)) $ $ &( `_))))

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Page 2: Time - University of Cambridge · 2003. 9. 7. · f ) ) ±) >))) ) & [ # \3] ) / :< /):;)) ^)) $ $ &( `_))))

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KernelMode

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set user mode (a privileged instruction)

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Page 3: Time - University of Cambridge · 2003. 9. 7. · f ) ) ±) >))) ) & [ # \3] ) / :< /):;)) ^)) $ $ &( `_))))

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Ú�AG5�J�>?> SPJ�>?> 146VJ.-H<PLDJ%> � d QRAGb�1���J73%3$/E<GAHARËÊá�\�À7e(-B1T][�e.g. 16-bit addresses - can address 64Kbytes suppose user-space 0 to 32K-1 OS-space 32K to 64K-1

user

OS

Ox0000

Ox7FFFOx8000

OxFFFF

e.g. 32-bit addresses - can address 4Gbytes

user

OS

Ox0000 0000

Ox7FFF FFFFOx8000 0000

OxFFFF FFFF

ª�LD<0A�<�JD/E<���O û�X M Kd�%1%/� %ý�Q#OBT*Kd����þ%þ�ûfú�ùIù@ú9ùG�

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CPU

address fault

no

yesphysicaladdress

limitM

emor

ybase

+

logicaladdress

Protection and Relocation Registers

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Page 12: Time - University of Cambridge · 2003. 9. 7. · f ) ) ±) >))) ) & [ # \3] ) / :< /):;)) ^)) $ $ &( `_))))

��©�µ�Ó� ���������2&(�

procedure

stack

main()

symbols

sys library

stack

sys library

procedure

symbols

main()Limit Base0

1

2

3

4

01234

1000

200

5000

200

300

0

200

5200

5300

56005700

5900

6900

0

5900

200

5700

5300

Logical Address

Space

PhysicalMemory

SegmentTable

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Per-processSegmentTables

Physical Memory

Shared

A

B

A

B

SystemSegment

Table

[DANGEROUS] [SAFE]

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P1 Offset

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L2 Address

L1 Page Table0

n

N

P2 L1 Address

Base Register

L2 Page Table0

n

N

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