嵌入式作業系統核心客製化與實現—使用Linux系統核心為例

Customization and Implementation of Embedded Operating System Kernel—Use Linux System Kernel

許壬皇(Ren-Huang Hsu)

指導教授 ： 方志鵬

國立臺北科技大學/電資學院/電機工程系所/碩士(2010年)

摘要

由於嵌入式系統的體積小、可攜性高、功率消耗低且價格相較於傳統 PC 便宜，現在市場上盛行的消費性電子產品，例如手機、個人數位助理 (PDA)、衛星導航系統 (GPS)等，都是由嵌入式系統所組成的；但因為嵌入式系統使用容量有限的快閃式記憶體 (Flash Ram) 當作儲存空間，加上原本配置的核心、檔案系統與應用程式等已佔去大部分，造成應用程式需要使用到儲存空間時出現不足的情況；因此，如何節省有限的儲存空間則成為了重要的課題。
本論文使用具有開放原始碼、維護容易等特性的 Linux 作為嵌入式系統的核心，依照所需的硬體環境編譯核心，並且使用呼叫圖來呈現核心的系統呼叫以及應用程式呼叫函式庫的結構，再從得到的呼叫圖中找出多餘的部份並刪除，藉此獲得較精簡的 Linux 核心；此法較傳統逐項測試刪除的方法更能清楚整體核心架構。再結合了試誤法 (Try & Error)，刪除檔案系統中未使用到的檔案，藉此來縮減檔案系統。本文使用 Qt 建立了「電子商品查詢系統」來驗證上述之方法，此系統結合了資料庫與圖形介面，給使用者透過觸控式螢幕的點選做商品查詢，查詢到的商品資訊、圖片等會顯示在觸控式螢幕上；根據實驗結果，核心、檔案系統、應用程式分別被精簡了26.7%、1.04%與22.86%，且系統能正常運作。

關鍵字

嵌入式系統 ； Linux ； 動態呼叫圖 ； 試誤法 ； Qt

並列摘要

Embedded systems have prevailed in recent years due to small size, high portability, low power consumption, and cheaper price in comparison to traditional PCs. The electronics products such as mobile phones, personal digital assistants (PDA), satellite navigation systems (GPS), etc., are now composed of embedded systems. These embedded systems typically used flash memory (Flash Ram) of limited capacity as a storage space, which has to carry the core of the original configuration, file systems and applications, etc. In practice, if the the kernel and the file system are not carefully configured, the space left for the applications is usually not enough. Therefore, how to save the limited storage space has become an important issue.
Because of the features of open-source and easy maintenance, this paper uses Linux as an embedded kernel of the system. We build the kernel of the environment in accordance with the hardware, and use the call graph to show the kernel of the system calls and the application of the structure of the program calls library, to get the excess part from call graph to find and remove, so as to obtain a more streamlined Linux kernel. In comparison to the traditional, which performs testing step by step to remove the kernel structure, our method gives an insight into the system architecture more clear, and reduces the customization time effectively. Coupled with the use of try and error method (Try & Error), remove the file system is not used to the file, thereby to reduce the file system. This article uses the Qt to construct an application (e-goods inquiry system, EGIS) to verify the effectiveness of our method, in which EGIS integrates user, graphical interface, and database. In EGIS, the user gives a query to the product information through the touch screen, EGIS fetches product information from the database, and pictures including the product information are displayed on the touch screen. Based on the experimental results, the size of the kernel, file system and the application program were respectively reduced to 26.7%, 1.04% and 22.86%, while the system still worked normally.

並列關鍵字

Embedded system ； Linux ； Dynamic Call Graph ； Try and Error method ； Qt

參考文獻

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