Lesson 2b (SPIN)

Question 1

Key points of Hydra

Answer 1

Kernel mechanism for resource allocation. Capability based resource access. Resource manager as coarse-grain objects to reduce border crossing overhead

Question 2

What was the disadvantage of MACH

Answer 2

It focused on portability which made it slow

Question 3

In SPIN where were extensions located

Answer 3

They were colocated with the kernel

Question 4

How was modularity enforced in SPIN

Answer 4

Using the compiler and a strongly typed language

Question 5

What language was SPIN written

Answer 5

Modula-3

Question 6

Which of the three OS structures is SPIN similar to?

Answer 6

DOS

Question 7

How did SPIN avoid security issues

Answer 7

Using logical protection domains

Question 8

What are the benefits that modula-3 provided

Answer 8

Safety+Encapsulation. type safety, auto storage management. Objects, threads, exception, generic interfaces

Question 9

How was fine grain protection provided

Answer 9

via capabilites

Question 10

What are capabilities essentialy

Answer 10

pointers

Question 11

How are Modula-3 pointers safe

Answer 11

They are type specific. This allowed for protection the os takes advantage of

Question 12

List the spin mechanisms for protection domains

Answer 12

Create, Resolve, combine

Question 13

Create

Answer 13

init with object file contents and export names

Question 14

resolve

Answer 14

names between source and target domain, Once resolved resource sharing at memory speed

Question 15

combine

Answer 15

to create an aggregate domain

Question 16

How are core services included

Answer 16

provided components implement specified interfaces

Question 17

What makes the extensions flexible

Answer 17

co-location systems extensions are dynamically linked

Question 18

What language in SPIN can applications be written in?

Answer 18

Any language

Question 19

Perfomance

Answer 19

It performed better than MACH comparable to Micro

Question 20

How does the kernel know where to send message and interupts

Answer 20

It has an event dispatcher and service can create handlers

Question 21

How are services siloed in memory

Answer 21

they are not, all services share the same address space

Question 22

How are system services built

Answer 22

As logical extensions

Question 23

What is the limit of an extensions

Answer 23

None really. The extension can be an entire OS

Question 24

How are events in the dispatcher ordered

Answer 24

Order of events isn’t guaranteed

Question 25

What are the relationships possible with handlres

Answer 25

many to one, one to one, one to many

Question 26

How many border crossings are needed to reach a service

Answer 26

One border crossing is needed to reach the services and another is needed for the results.

Question 27

Where is the memory management

Answer 27

It is added as a service

Question 28

How does the kernel talk to the memory manager

Answer 28

SPIN defines the interface

Question 29

How would a page fault get routed

Answer 29

A handler would be in place for the kernel trap that the kernel would dispatch to the memory management service.

Question 30

Where is the cpu scheduler located

Answer 30

As a service. It is not built in.

Question 31

What is Stand

Answer 31

Strand is a unit of scheduling set by the global scheduler which interacts with application thread package.

Question 32

How is cpu time scheduled

Answer 32

Services given thread time by SPIN can schedule cpu time how they like