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- #README
- Try below command
- ```
- gcc -g -m32 lab0_ex3.c 2>&1|tee make.log
- ```
- If you get gcc's error, try to read make.log and fix the bugs.
-
- If gcc successed, then you will get a.out.
-
- Try to answer below question.
-
- 对于如下的代码段，
- ```
- ...
- #define STS_CG32 0xC // 32-bit Call Gate
- #define STS_IG32 0xE // 32-bit Interrupt Gate
-
- #define SETGATE(gate, istrap, sel, off, dpl) { \
- (gate).gd_off_15_0 = (uint32_t)(off) & 0xffff; \
- (gate).gd_ss = (sel); \
- (gate).gd_args = 0; \
- (gate).gd_rsv1 = 0; \
- (gate).gd_type = (istrap) ? STS_TG32 : STS_IG32; \
- (gate).gd_s = 0; \
- (gate).gd_dpl = (dpl); \
- (gate).gd_p = 1; \
- (gate).gd_off_31_16 = (uint32_t)(off) >> 16; \
- }
-
- /* Gate descriptors for interrupts and traps */
- struct gatedesc {
- unsigned gd_off_15_0 : 16; // low 16 bits of offset in segment
- unsigned gd_ss : 16; // segment selector
- unsigned gd_args : 5; // # args, 0 for interrupt/trap gates
- unsigned gd_rsv1 : 3; // reserved(should be zero I guess)
- unsigned gd_type : 4; // type(STS_{TG,IG32,TG32})
- unsigned gd_s : 1; // must be 0 (system)
- unsigned gd_dpl : 2; // descriptor(meaning new) privilege level
- unsigned gd_p : 1; // Present
- unsigned gd_off_31_16 : 16; // high bits of offset in segment
- };
-
- ...
-
- ```
- 如果在其他代码段中有如下语句，
- ```
- unsigned intr;
- intr=8;
- SETGATE(intr, 0,1,2,3);
- ```
- 请问执行上述指令后， intr的值是多少？
-
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