课程名称︰虚拟机器
课程性质︰选修
课程教师︰徐慰中
开课学院：电资学院
开课系所︰资工所、网媒所
考试日期（年月日）︰2015.03.19
考试时限（分钟）：
试题 :
To implement an emulation system, we have the following possible choices:
A) Interpretation
B) Threaded interpretation
C) Static binary translation
D) Dynamic binary translation
1) Which one is the fastest method if the guest code has no loops and runs
only once.
A) B)
C) D)
2) Which one can emulate faster if the guest code has many loops with large
iteration counts
A) B)
C) D)
3) Which one may have tough challenges when the guest ISA has variable length
instructions?
A) B)
C) D)
4) Which one may have difficulties if the guest code can modify its
instructions on-the-fly (e.g. SMC).
A) B)
C) D)
5) Which one is often used in process virtual machines for ISA migration.
A) B)
C) D)
6) In BT, which of the following methods can speed up the processing of direct
branches?
A) Register mapping B) Local address look-up cache
C) Translation Chaining D) Shadow Stack
7) In BT, which of the following can speed up the processing of indirect
branches?
A) Indirect branch target prediction
B) Indirect branch target cache
C) Shadow Stack
D) Branch folding
8) All indirect branch optimizations in DBT are trying to avoid
A) Branch mis-predictions B) Exceptions
C) Instruction cache misses D) Context switch cost
9) Which of the following BT system is the easiest?
A) x86-32 to x86-64 B) MIPS to Alpha
B) ARM to x86-32 C) x86 to ARM
10) To build a BT that translate x86-64 (i.e. x64) to x86-32 (IA32), which of
the following are most difficult to deal with?
A) Translating ADD instructions
B) Translating Push/Pop instructions
C) Translating Load/Store (MOV) instructions
D) Register mapping
DBT systems usually implement the following optimizations:
A) Register mapping
B) Translated code optimizations
C) Translation chaining
D) Indirect branch handling.
11) In your opinion, what should be the order of importance in terms of
performance?
A) A > B > C > D
B) B > A > C > D
C) A > C > D > B
D) C > A > D > B
13) What tough challenges a DBT must face when translating x86-32 code to MIPS?
A) Register mapping
B) Condition code emulation
C) Misaligned memory references
D) Code discovery
14) What would be a good target architecture for ISA migration?
A) machine with many general purpose registers
B) machine supports condition codes
C) machine supports both big endian and little endian
D) machine supports FMAC (high precision FP math)
15) Which of the following tools are based on DBT?
A) PIN
B) QEMU
C) LLBT
D) Genymotion
16) Optimizations in DBT may slow down short running apps. How does HQEMU
overcome this challenge?
A) Doing optimizations in a separate/parallel thread
B) Rely on extensive off-line profiling
C) Let short running apps going thru the original fast lane
D) HQEMU does not care short running apps
Ans:
1) B
2) C
3) C
4) C
5) D
6) C
7) A, B, C
8) D
9) A
10) C, D
11) C
13) B, C
14) A, C
15) A, B, D
16) A, C