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Embedded Software Lab.

OS 실습Embedded Software Lab.

박대준 , 박은수

Lecture 3. Kernel fusing, printk

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Embedded Software Lab.

Cross Compiler 설치 & 코드 다운로드Cross Compiler 설치 :

$ sudo apt-get install gcc-arm-linux-gnueabihf

코드 저장 위치 설정 :

$ cd $HOME

$ mkdir work

$ cd work

소스 코드 다운로드 : $ git clone --depth 1 https://github.com/hardkernel/linux.git -b odroid-

3.8.y

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Embedded Software Lab.

http://odroid.us/mediawiki/index.php?title=Step-by-step_Cross-compiling_a_Kernel 참고

$ sudo apt-get install libncurses5-dev

Toolchain 환경변수 설정 빌드

Cross-compile 설정

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Embedded Software Lab.

커널 컴파일

$ cd linux-odroid-3.8.y/

$ export ARCH=arm$ export CROSS_COMPILE=arm-linux-gnueabihf-$ make odroidu_defconfig $ make zImage –j8$ make modules

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Embedded Software Lab.

• mkdir ../rfs

• export INSTALL_MOD_PATH=$PWD/../rfs

• make modules_install

• cd ../rfs

• # remove symlinks that point to files we do not need in root file system

• find . -name source | xargs rm

• find . -name build | xargs rm

• # Compress

• sudo tar -cvzf ../modules.tgz .

• cd ../

Module

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Embedded Software Lab.

• Copy source_tree/arch/arm/boot/zImage to odroidu3:/boot/

zImage 설치

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Embedded Software Lab.

• tar -xvzf modules.tgz

• rm modules.tgz

• sync

• reboot

Module 설치

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Embedded Software Lab.

• The kernel print function

• behaves almost identically to the C library printf() func-tion

• callable from just about anywhere in the kernel at any time

• unusable before a certain point in the kernel boot process– early_printk()

printk()

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Embedded Software Lab.

• printk("<4>This is a warning!\n");

• printk("<7>This is a debug notice!\n");

• printk("<4>did not specify a loglevel!\n");

• printk(KERN_WARNING "This is a warning!\n");

• printk(KERN_DEBUG "This is a debug notice!\n");

• printk("I did not specify a loglevel!\n");

printk-Loglevels

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Embedded Software Lab.

H/W