| Embedded system is an application-centric computer system concerning on a special task.Because of its limited rescources, it should be low cost and efficient. Its designing includeschoosing processer, designing hardware, programing application according to therequirements, and transplanting operating system however have to be modified andconfigured from the exiting operating system. The operating system is so complicated that theconfiguring and tailoring cost so much time to get a limited result.Aiming the problem above, paper puts forward a new method to tailor the linux kernel.First program an instrumentor to put a sentence that makes a variable add at the beginning ofevery linux kernel function. So the variable put in every function means the frequence of thefunction being called. After the testing coverage，the value of the varialbe will be get by thenewly added system call. The function not being called would be likely removed whentailoring the kernel. The realization, testing process on the x86and the changing when used inembedded system are explained in detail. The tests show this method can tailor the unusedfunction that cannot be removed by the configuration tools, provide configuration suggestion,and make the kernel simply, make the configuration convenient.The primary converage are following:（1） The instrumentor designing: summarizing the keywords set; translating theregular expression; formulating the DFA table; programming the instrumentor to insertsentence; designing a distributed instrumentor to reduce the time cost.（2） Getting the kernel data: analyzing the x86protected model and the processmanagement, address space, system call in linux kernel, adding a new system call to help theconsumer process access the kernel space to get and record the data in a file.（3） Testing coverage and data analysis: combining the context above; realizing the instrument and testing coverage; getting the data and tailoring the kernel according to the data;last testing the result. |
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