Lab 5 Department of Computer Science and Information Engineering National Taiwan University Lab5 - OS Kernel 2014/10/21/ 16 1

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Learn how to build Linux kernel image for PXA /10/21/ 16 2

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Host System  Windows XP  Build System  VirtualBox + Ubuntu 8.04  Target System  Creator XScale PXA270  Software  Linux for PXA270  linux creator-pxa270.patch  mkimage utility  Root filesystem image (15M)  You can find all software on RSWiki CSL Course Software.RSWiki CSL Course Software 2014/10/21/ 16 3

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  After the 1.0 release and prior to version 2.6, the number was composed as “A.B.C”, where the number A denoted the kernel version, the number B denoted the major revision of the kernel and the number C indicated the minor revision of the kernel.  In 2004, after version was released, the kernel developers no longer uses this system, instead now simply incrementing the third number, using a fourth number as necessary.  In 2011, the kernel version was bumped to 3.0 for the release following , to commemorate the 20th anniversary of Linux. 2014/10/21/ 16 4 Reference: wikipedia – Linux kernel

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Step 1: download Linux source codes (mt-linux tar.gz) for PXA270.mt-linux tar.gz  Step 2: extract the source codes.  Step 3: apply the patch.  % cd pxa270/create-pxa270  % wget creator-pxa270.patch creator-pxa270.patch  % patch -p0 < linux creator-pxa270.patch 2014/10/21/ 16 5

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Step 4: configure the Linux kernel (check Lab3’s arm-unknown-linux-gnu- * toolchain path in PATH).  % cd../linux  % make mrproper  % make creator_pxa270_defconfig  The “ make _defconfig ” command will create.config by the default symbol values from arch/ /configs/ _defconfig.  Step 5: compile Linux kernel.  % make  The resulting zImage in arch/arm/boot is the compressed kernel image we want. 2014/10/21/ 16 6

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  The Linux kernel build system (Kbuild) includes support for a variety of configuration methods, the most commonly used method is:  % make menuconfig  Please install libncurses5-dev package in Ubuntu.  Make sure your screen is large enough to display the configuration. 2014/10/21/ 16 7

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Many features and drivers are available as modules, and they are possible to choose whether to build features into the kernel.  Please always build into the kernel, i.e.,, in our Labs.  Once the kernel has been configured, you can quit the kernel configuration menu via Esc key or the Exit menu item.  Choose “Yes” to save the new configuration into a new.config file.  You can use “ ls -a ” to check the file. 2014/10/21/ 16 8 built-in module

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  The Creator XScale PXA270 board has 32MB flash and 64MB SDRAM.  Flash memory address range: 0x to 0x  SDRAM address range: 0xA to 0xA  Recall that U-Boot has determined the location of kernel image. CONFIG_BOOTCOMMAND "run linux" CONFIG_LINUX bootm  The locations and sizes of kernel image and root filesystem are also determined by Linux kernel (in arch/arm/mach-pxa/mach-creator- pxa270.c ). 2014/10/21/ 16 9

Lab 5 Department of Computer Science and Information Engineering National Taiwan University 2014/10/21/ xA xA RAM U-Boot Flash 0x x x diag 0x x Linux kernel 1 Root Filesystem 0x U-Boot parameters 0x x01C00000 Linux kernel 2U-Boot 0xA3F80000

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Based on the memory layout, we can configure our Linux kernel. static struct mtd_partition creator_pxa270_partitions[] = {... },{ name: "Kernel", offset: 0x , size: 0x , // 4M mask_flags: MTD_WRITEABLE },{ name: "Filesystem", offset: 0x , size: 0x00F00000, // 15M } /10/21/ 16 11

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  We use U-Boot as the bootloader on PXA270, we need to convert the OS kernel image vmlinux (which zImage is compressed by) to U-Boot bootable image ( uImage ).  Step 1: get raw binary file.  % arm-unknown-linux-gnu-objcopy -O binary -R.note -R.comment -S arch/arm/boot/compressed/vmlinux linux.bin  Step 2: compress kernel image (optional).  % gzip -9 linux.bin 2014/10/21/ 16 12

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Step 3: download mkimage.mkimage  Step 4: add header.  % chmod +x mkimage  %./mkimage -A arm -O linux -T kernel -C gzip -a 0xa e 0xa n "CSL Lab5 Kernel" -d linux.bin.gz uImage  If you skip step2, please use -C none and -d linux.bin.  mkimage is in the tools folder of U-Boot source codes.  You can see the mkimage usage by executing without arguments.  The resulting uImage is the U-Boot image we want. 2014/10/21/ 16 13

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Please refer to Lab2 to copy new Linux kernel and root filesystem to flash.  Step 1: download new 15M rootfs (root filesystem).rootfs  Step 2: copy your uImage to flash.  Step 3: copy new rootfs to flash. (take about 7 minutes)  Step 4: reset PXA270, now you can see your own Linux kernel is booted (the message “CSL Lab5 Kernel”).  Please use “ df -h ” to check the size of filesystem. 2014/10/21/ 16 14

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  However, the driver of the network card on PXA270 does not be configured in default Linux configuration.  Please try to configure the driver and build it into your kernel.  Please use “ ifconfig eth0 ” to check that your network card works. 2014/10/21/ 16 15

Lab 5 Department of Computer Science and Information Engineering National Taiwan University  Show that you can use “ tftp ” on your Linux kernel which has a 15M filesystem.  Please hand in your lab report to the FTP.  Server:  Username: csl2014  Password: csl2014HomeWork  Directory: lab5  Please use this format for filename: “G# Ver#”, where G# is your group id and Ver# is revision version number.  E.g., G1 Ver2 2014/10/21/ 16 16