80386 interrupt and exception

In addition to maintaining 8086/80386 80386 related functions, but also enhanced interrupt handling capability, and the concept of "exception" concept. This article will introduce the 80386 interrupt and exception mechanism. Download the article all the source code.

8086/8088 to break into the internal interrupt and external interrupt two categories. In order to support multi-tasking and virtual memory and other functions, 80,386 external interrupt known as the "break", the internal interrupt as "abnormal." As with the 8086/8088, 80386 usually between the two commands to respond to interrupt or exception. 80386 handle up to 256 interrupt or exception.

1. Interrupted

On the 80386, the interrupt is caused by asynchronous external events. External events and interrupt response and is not related to the implementation of the directive. Typically, the interrupt to indicate I / O device has completed an operation. As with the 8086/8088, 80386 INTR and NMI are two pins accept external interrupt request signal. INTR accepted maskable interrupt request. NMI received interrupt request can not be shielded. In 80386, the flag register IF flag in EFLAGS to decide whether screening can shield interrupt request.

External hardware through an interrupt request signal INTR the same time, but also to give an 8-bit processor interrupt vector. Processor in response to maskable interrupt request, read the paper by the external hardware interrupt vector number. Processor interrupt vector of this number and does not provide. But in the specific computer system, the system must meet the set of software and hardware, so given the interrupt vector number corresponds not only with the external interrupt sources and interrupt vector number used to avoid the appearance of conflict. 8259A programmable interrupt controller chip can work with the 80386, can be set to the processor according to the interrupt vector number, can handle the priority interrupt request. Each 8259A chip can support 8 interrupt request signal, if you use 9 8259A chip (a master piece, eight from the film), would enable a single pin INTR 80386 accepted up to 64 interrupt sources, interrupt request signal .

Processor does not mask the interrupt request from the NMI. Processor in response to NMI interrupt is not received from the external hardware interrupt vector number. And 8086/8088, as in 80386, the non-maskable interrupt the corresponding interrupt vector number is fixed at 2. For non-maskable interrupt nesting, when receiving an NMI interrupt, the processor again in response to the internal shielding of the NMI, the implementation of the screening process until after the end of the interrupt return instruction IRET. Therefore, NMI handler should be the end of IRET instruction.

2. Exception

80386 instruction exception is detected during the implementation of irregular or illegal conditions are present. Abnormality in the execution of the instructions have a direct link. For example, the implementation of the divide instruction, the divisor is equal to 0. Again, the implementation of instruction privilege level is not correct when found. When these situations occur, the directive can not be completed successfully. Software interrupt instruction "INT n" and "INTO" also classified as abnormal and not interrupt, because the implementation of these instructions produced anomalies.

80386 identify different types of anomalies, and to give each category a different interrupt vector number. After the exception occurs, the processor so as to respond to interrupt handling exceptions. That under the interrupt vector number, switch to the corresponding interrupt handler. This interrupt handler is called the exception handler may be more appropriate.

Abnormal according to whether the procedure caused the restoration and recovery point can be different, to be further classified as abnormal fault (Fault), trap (Trap) and suspension (Abort). We were the corresponding exception handler is called fault handler, trap handlers and termination handlers.

Failure is caused by abnormalities in the instruction before it is notified to the system anomaly an exception. That the fault is 80386 can be excluded. When control is transferred to the fault handler, the saved CS and EIP values break point to lead to failure of the command. Thus, the fault handler to troubleshooting, the implementation of the IRET to return to the program caused by failure to execute, just lead to failure of command can be re-implemented. This re-run, no additional operating system software to participate. Failure of the findings may begin before the command may also be in the instruction execution period. If failures are detected during instruction execution, then the suspension of fault instruction, and instruction operands to restore the value before the instruction started. This will ensure the re-implementation of fault instruction to get the right results. For example, during the execution of an instruction, if we find there is no section, then stop the implementation of the directive, and notify the system to produce Fault, the corresponding segment fault handler can load the troubleshooting section of way, after which the original instruction can be successfully implemented, at least not non-existent fault segment occurred.

Trap is caused by abnormalities in the following instructions to inform the anomalies An exception to the system. When control is transferred to the exception handler, the saved CS and EIP break point to lead to trap the value of the next instruction to execute instructions. The next instruction to be executed, not necessarily the next instruction. Therefore, the trap handler does not always save the breakpoints according to the anti-push identify an exception instruction. When the trap handler in turn, lead to the completion of trap instruction to be normal, it is possible to change a register or memory cell. Software interrupt instruction, single-step exception is the example of the trap.

Suspension is a serious situation in the system, an exception notification system. Caused by the suspension order can not be determined. Produce termination, is the implementation of the program can not be reinstated. System receives the suspension, the processing procedure to re-establish the system forms, and may restart the operating system. Hardware failures and system tables in the illegal value or inconsistent value is suspended example.

3. Priority

In an instruction execution period into more than one interrupt is detected, or abnormal, then press the priorities listed in the table notification system. The highest priority interrupt or exception notification system, other lower-priority exception being abandoned, while the higher-priority interrupt will remain hanging.

80386 responses

Interrupt / exception priority interrupt / exception types the highest priority fault other fault 鈫?debug trap instruction INT n and INTO 鈫?鈫?NMI debug trap minimum disruption 鈫?INTR interrupt






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Jobs: find a good quality of the work of eight major

Employment Guidance Centre Beijing not long ago, college graduates more than 150 state-owned enterprises, private and high-tech enterprises, foreign-invested enterprises in human resources and some colleges and universities conducted a survey of the characteristics of the following eight Students welcomed by most employers. In fact, not just the graduates, any person who would like to find a good job, need to have the following qualities.

Identity Corporate Culture in the shortest time

"Corporate culture is the spiritual pillar of the survival and development. Staff only recognized corporate culture can grow with the company." Shell's head of human resources, said, "We are in recruitment will focus on job attitude and examine students professional orientation is consistent with company needs, individual self-understanding and development of space is the company's corporate culture is consistent with the trend. "

Beijing College Graduates Career Guidance Center experts suggest: "college students jobs before, to focus on selected businesses have some understanding of corporate culture, and to see whether they agree with the enterprise culture. If you want to join this enterprise, we should make their own values and enterprises consistent with the values advocated in order to enter the enterprise, the initiative to put myself into the team, the enterprise culture to constrain their behavior, as the company due diligence. "

Sense of belonging and loyalty to a team of enterprise

Survey showed that state-owned enterprises, foreign-invested enterprises, private enterprises are the human resources agreed that the company would prefer to be an adequate loyalty, even if capacity was close, and also in but do not want to be an extraordinary ability to play fast and loose people.

A company's human resources manager that the staff of the company loyalty, reflected in the staff and the success and prosperity of the company's interest, no matter the boss is not present, must earnestly work, encouraged to go to work. Employees a sense of belonging, his loyalty and ultimately let him achieve the desired goals, thus becoming a trusted person, a boss to hire the person, a right-hand man who could become the boss.

Beijing College Graduates Career Guidance Center Han Chunguang teacher, said: "Enterprises in the recruitment of staff, in addition to test their ability level, the individual behavior is the most important assessment. Did not conduct the people can not use Yebuzhide culture. Conduct of The most important aspect is the company loyalty. that is both able and loyal business people, every business needs is the best talent. "

Not demanding alumni of prestigious universities as long as the comprehensive quality

Ji-Tong Network Communication Co., Ltd. of human resources who said, "Our company is not demanding elite and professional counterparts, even more rare in the profession, as long as the overall quality of a good student, learning ability and adaptability, a problem in time to see crux of the matter, and in time to mobilize their own capacities and have learned to quickly release their potential, develop a workable plan, it will also be welcomed. "

Survey analysts pointed out that "As enterprises increased competition, companies pay more attention to the quality of talent. Because the talent is to create products for enterprises to win a major factor in the profit. Some companies, especially technology companies with low levels, and not just value students academic performance, and more attention to the overall quality of students, this is the employment characteristics of modern enterprises. their overall quality is more important than academic qualifications. "

With dedication and professionalism

"Now, some rather low-quality young career, there was a young man, the reasons for being late for work the morning last night watching TV actually is seen too late. New to the students work problems or difficulties encountered, not timely communication with colleagues, until the leadership in the only reported delays in the progress of work, these are not the dedication and professionalism of poor performance. "Zhongguancun Electronic Co., Ltd. Human Resources Department who said," Businesses are looking to strengthen the community school students survival outlook, values education, strengthen the professional quality of students, emotional intelligence, adaptability and psychological quality. With the dedication, the other is relatively easy to cultivate quality. "

Professional technical capacity

Beijing Science and Technology AG, a human resources manager, said, "Professional skills of our employees the most basic quality requirements, IT industry to hire and pays more attention when the technical capacity of applicants. When the applicants in the recruitment of the same capacity if, perhaps will give priority to recruit graduate students. However, after the academic level into the company is not the main measure, and will pay more attention to practical techniques, who can do it and who is to have a skill, who Take the high wages. "

Strong communication skills, have affinity

BOE Technology Group, the head of the Ministry of Personnel, said: "Our company Ren Wei, college students need improvement Nengli is communication capabilities. Qiye need is to Yunyongziji good for communication skills and Qi Ye Neiwaiyouguan personnel contacts, to co-operating with concentric Tong Germany, completed the organization's mission and purpose of man. "

Teamwork and collaboration are

Shanghai Automotive Industry (Group) Corporation, the human resources person said: "From the perspective of the growth of talent, a person belongs to the team, there must be spirit of teamwork and collaboration, and only in an atmosphere of good social relations, personal growth will be more successful. "

With a passion to work

"Passion is a powerful emotion, a kind of people, work and faith strong emotion." Guiding College Graduates Beijing Ren Zhanzhong, director of "The enthusiasm of the employees without a job can not complete their high quality work, let alone to create results. Only those who have a genuine desire on their enthusiasm, are likely to put their wishes into a beautiful reality. "







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