bsp customization and porting of linux on arm
Contents
1. This paper discussed about Yocto build environment and was successfully installed on the host system Ubuntu 12 04 LTS U boot Kernel and filesystem were successfully configured and cross compiled as per Freescale Sabresd embedded board specifications At the end as an example Ubuntu filesystem was ported to the same board The boot time recorded was 32 seconds ACKNOWLEDGEMENTS I would like to thank my master and my parents REFERENCES 1 De Goyeneche J M De Sousa E A F Loadable Kernel Modules Software IEEE Vol16 Issuel pp 65 71 Jan Feb 1999 2 Wooking and Tak Shing Porting the Linux kernel to a new ARM Platform Aleph One vol 4 summer 2002 3 Vincent Sanders Booting ARM Linux rev 1 10 June2004 http www simtec co uk products S WLI NUX files booting_article html Volume 03 Issue 05 May 2014 Available http www ijret org 695 IJRET International Journal of Research in Engineering and Technology eISSN 2319 1163 pISSN 2321 7308 4 Hu Jie Zhang Gen bao Research transplantation method of embedded linux kernel based on ARM platform Information Science and Management Engineering ISME 2010 International Conference Vol2 pp 35 38 7 8 Aug 2010 5 Chun yue Bi Yun peng Liu Ren fang Wang Research of key technologies for embedded Linux based on ARM Computer Application and System Modeling ICCASM 2010 International Conference 22 24 Oct 2010 E ISBN 972. embedded field and is currently Project Manager at TES Electronic Solutions Harish Mekali has graduated from PESIT Bangalore He has been key figure in many research works at BMSCE Volume 03 Issue 05 May 2014 Available http www ijret org 696
3. 8 1 4244 7237 6 6 The DENX U Boot and Linux Guide available at www denx de 7 Pratyusha Gandham Ramesh N V K Porting the linux kernel to an arm based development board International Journal of Engineering Research and Applications IJERA Vol 2 Issue 2 Mar Apr 2012 pp 1614 1618 8 Divya Sharma Kamal kanth Porting the Linux Kernel to Arm System On Chip And Implementation of RFID Based Security System Using ARM International Journal of Advanced Research in Computer Science and Software Engineering IJARCSSC Vol3 issue5 May 2013 9 K Eshwar Kumar M Kamaraju Ashok Kumar Yadav Porting and BSP Customization of Linux on ARM Platform International Journal of Computer Applications 0975 8887 Volume 80 No 15 October 2013 10 http www yoctoproject org docs 1 4 ref manual ref manual html required packages for thehost development system 11 1 MxX 6Dual 6Quad BSP Porting Guide Rev L3 0 35_ 1 1 0 01 2013 Freescale Semiconductor inc BIOGRAPHIES Manjunath Joshi completed his B E from VTU Belgaum Karnataka India He is currently pursuing Masters at CMRIT Bangalore and is working as an intern at d TES Electronic Solutions a German based Embedded Design Company Harsha B K is currently working as an assistant professor at CMRIT Bangalore He did his masters from VTU Belgaum Vivek Kaushik completed his bachelors from Chandigarh He has ten years of experience in
4. IJRET International Journal of Research in Engineering and Technology eISSN 2319 1163 pISSN 2321 7308 BSP CUSTOMIZATION AND PORTING OF LINUX ON ARM CORTEX BASED LMX6 PROCESSOR WITH YOCTO BUILD ENVIRONMENT Manjunath Joshi Harsha B K Vivek Kaushik Harish Mekali Student Electronics and communication Department CMRIT Karnataka India Assistant Professor Electronics and communication Department CMRIT Karnataka India Project Manager Software Department TES Electronic Solutions Karnataka India Assistant Professor Electronics and communication Department BMSCE Karnataka India Abstract In the last few years the need for compact and embedded systems has expanded in all fields With regard to this development ARM development platform is the ideal and practical answer for planning a new product design ARM platforms carry a generally positive result regarding speed accuracy adaptability size and cost Every new embedded design at the back an operating system must be modified appropriately for the specifications of the embedded target It would be a huge added advantage to have an embedded design running an OS In particular this paper underlines the BSP Board Support Package customization of Linux operating system and porting mechanism to FreeScale SabreSD an 1 MX6 processor based embedded board with the help of Yocto build environment The usual method of going for Linux Target Image Builder LTIB is conside
5. SD MMC card reader it will be used to transfer the boot loader and kernel images to initialize the partition table and copy the root filesystem To simplify the instructions it is assumed that a 4GB SD MMC card is used The Linux kernel running on the Linux host will assign a device node to the SD MMC card reader To identify the device node assigned to the SD MMC card enter the command cat proc partitions 6 4 Copying Root Filesystem to SD Card First a partition table must be created Create a partition at offset 16384 in sectors of 512 bytes enter command Volume 03 Issue 05 May 2014 Available http www ijret org 694 IJRET International Journal of Research in Engineering and Technology sudo fdisk dev sdb The Filesystem format ext3 or ext4 is a good option for removable media due to the built in journaling To format the partition sudo mkfs ext3 dev sdb1 Or sudo mkfs ext4 dev sdb1 6 5 Copy the Target Filesystem to the Partition mkdir home user mountpoint sudo mount dev sdb1 home user mountpoint Extract sabresd_rootfs package to certain directory extract sabresd_rootfs tar bz2 to home user mountpoint tar xvjf sabresd_rootfs tar bz2 C home user mountpoint Note Ubuntu filesystem may be freely available for demo purpose on websites As an example OS it can be used along with our customized kernel and U boot 6 6 Copying Boot Loader Image to SD Card Enter the following c
6. are Bootloader Kernel Filesystem Bootloader is an initializing code for a particular board which is executed at the power on or reset the board Here the proposed boot loader is U Boot boot loader To boot the Linux the boot loader has to load the modules into the eISSN 2319 1163 pISSN 2321 7308 memory one is the Linux kernel and another one is the Filesystem 6 Kernel is a software layer that interfaces with the hardware It is responsible for interfacing all peripherals that are currently connected to the system and running in user mode down to the physical hardware and allowing processes to get information from each other using inter process communication 9 Filesystem is the way in which files are named and where they are placed logically for storage and retrieval The DOS Windows Macintosh and UNIX based operating systems all have Filesystems in which files are placed somewhere in a hierarchical tree structure A file is placed in a directory or subdirectory at the preferred place in the tree structure Filesystems require conventions for naming files A Filesystem also includes a format for identifying the path to a file through the structure of directories Applications libraries High level abstractions File Network systems protocols Low level interfaces Hardware Fig 3 Basic Embedded Linux Structure 3 BUILDING LINUX KERNEL PLATFORM This section incorporates to set up the building envi
7. be embedded system There is a greater extent demand on the embedded system market According to the present scenario the demand on embedded CPUs is more times as large as general purpose CPUs As applications of the embedded systems become more multifaceted to build the operating system and preparing development environment became crucial 9 1 1 Embedded Linux System Figure 1 shows the layered architecture based upon the OS directory structure and also indicates the how the application in the device accessing the hardware The main concentration is only the Board Support Packages It depends on the architecture of that OS If the architecture is ARM then the corresponding will be created according to the target platform The BSP is in detailed as follows Board Support Packages BSP is a collection of the binary code and support files that can be used to create a Linux kernel firmware and Filesystem images for a particular target In other words a Board Support Package BSP is an implementation specific support code for a given board that conforms to a given operating system It has commonly had Volume 03 Issue 05 May 2014 Available http www ijret org 691 IJRET International Journal of Research in Engineering and Technology a boot loader that contains the minimal device support to load the operating system and device drivers for all the devices in a target system BSP in a layman s words can be a menu from which
8. he can choose The menu contains all the essential features that a board can have Customization is specific to a board as to whether it supports that particular feature or not Porting on the other hand is making sure that the software which was customized runs on the target platform Tools and Applications GNU libe system libraries system call Interface a S memor init scheduler Y manager network loadable interface modules Device Drivers Architecture dependent code Hardware Fig 2 Embedded Linux System layered architecture 2 THE EMBEDDED OPERATING SYSTEM The term Operating system is referred to as it s a special code that acts as an intermediate between the hardware and the user 5 The main goals of the operating system is to make the system is convenient to use Hiding the hardware details and utilizing the resources in efficient manner 1 The following are the most important factors to choose an Embedded Operating System 4 Full source availability Technical support real time performance compatibility customizable open source the processor it supports purchase price simplicity easy to use availability of the software development tools small memory footprint middleware software drivers and finally it is also supports the other architectures also The layered architecture of basic Embedded Linux is shown in the Figure 2 The operating system can be divided into three modules They
9. hows the type of LCD used and its resolution The configured drivers are the Memory Technology device drivers MTD Block Devices I2C Support GPIO Support Multimedia support USB Support MMC Card support Real time clock Sound card support Power supply Class support Watchdog timer support These are the required drivers for customizing The selection of options either lt gt or lt M gt modules as per our requirement Figure 5 represents the configuration of kernel eISSN 2319 1163 pISSN 2321 7308 Linux x86_64 3 0 35 Kernel Configuration menu lt Enter gt selects submenus gt Highlighted letters s features Press lt Esc gt lt Esc gt to exit lt gt for Help lt gt 1 gt module capable hi DMA memory allocation support General setup gt Enable loadable module support gt Enable the block layer gt Processor type and features gt Power management and ACPI options gt Bus options PCI etc gt Executable file formats Emulations gt Networking support gt Device Drivers gt Firmware Drivers gt File systems gt Kernel hacking gt Security options gt Cryptographic API gt Virtualization gt Library routines gt Load an Alternate Configuration File Save an Alternate Configuration File Fig 4 kernel configuration by menuconfig Configuration is to set up the kernel and u boot as per the board specificatio
10. mulator written with GTK It is lightweight and simple that drives serial ports Ubuntu users wanting a graphical terminal program can install gtkterm Later versions which include many bug fixes can be obtained from the current maintainer s website On a Windows PC you could use HyperTerminal or TeraTerm Insert the SD card into the SD card slot of the target board Connect the target board to host machine using RS232 serial cable Apply power supply to the target board 7 6 2 Creating Partition in SD Card Pre requisite 4GB SD MMC card Card Reader Flashing Utility Gparted Install Gparted utility and run it after installation sudo apt get install Gparted Select 4 GB SD MMC Card from drop down menu shown in Fig 5 as 3 64 GiB dev sdc GParted GParted Edit View Device Partition Help dev sdc 3 64 GiB dev sdc2 3 62 GiB Partition File System Mount Point Label Size Used unallocated unallocated 4 00 MiB dev sde1 s fatis media Boot imx6qs Bootimx6qs 8 00MiB 5 02M dev sdc2 S E ext3 media 5f88e503 a0a9 47db a540 91cf2ce70f40N 3 62 GiB 461 92 M Fig 5 Creating partitions in SD card using Gparted The card will be mounted and any existing partitions will be visible First unmount all the partitions and then delete those partitions Create new partitions e Leave 100 MB as Free Space preceding e Choose Filesystem as ext4 e Give label as rootfs e Click Add to create the partition 6 3 Requirement An
11. ns of our interest U boot is open source and is available at http sourceforge net projects uboot or can be downloaded from Freescale community website if you are a registered user 4 COMPILATION 4 1 Compiling Kernel Source We need to set the path to cross compile Tool chain is a cross compiler with necessary libraries binary utilities We are using fsl linaro toolchain as a cross compiler export ARCH arm export CROSS_COMPILE arm none linux gnueabi export PATH PATH opt freescale usr local gcc 4 6 2 glibc 2 13 linaro multilib 2011 12 fsl linaro toolchain bin make sabresd_defconfig make ulmage Output file ulmage will be under arch arm boot uImage 4 2 Compiling u boot Cross compiler for arm v9 arm none linux gnueabi gcc 4 3 Compiling Filesystem Ubuntu filesystem is freely available on the freescale community Select machine and prepare the bitbake s environment MACHINE imx6qsabresd source setup environment build fb e bake the image recipe bitbake Linux image Bake The first time can take several hours Volume 03 Issue 05 May 2014 Available http www ijret org 693 IJRET International Journal of Research in Engineering and Technology eISSN 2319 1163 pISSN 2321 7308 5 SABRESD BOOT SET UP 5 1 Booting the 1 MX 6Dual 6Quad SABRE SD Board The boot modes of the 1 MxX 6Dual 6Quad SABRE SD board are controlled by the boot configuration DIP switches on the board Serial Downl
12. oad Mode for MFGTool No dedicated boot dips are reserved for serial download mode on i MX 6 SABRE SD boards Therefore a tricky method is used to enter serial download mode After HID Compliant device is detected it means that the board has entered serial download mode Insert the SD card into SD3 slot Another way to do this is to configure an invalid boot switch setting for example set all the dips of SW6 to off 11 5 2 Booting from SD Card from Slot2 The following tables show the dip switch settings for SD2 boot Table 1 Boot switch setup for SD2 boot J500 Switch S DI D2 D3 _ D4 DS_ D6 D7 D8 Note S stands for Switch and S6 is Switch 6 Table 2 Boot switch set up for SD Card from Slot3 S D1 D2 D3_ D4 D5_ D6 _ D7 D8 Table 3 Boot switch set up for SD Card from eMMC 4 4 S DI D2 D3 D4 DS_ D6 D7 D8 Table 4 Boot switch set up for SD Card from SATA S D1 D2 D3 D4 DS_ D6 D7 D8 6 RESULTS The successful building of the Yocto generates a file which is an encrypted file that is bootable on i mx6 series i e ARM9 based development boards Next few steps explain flashing images and root file system to SD card 6 1 Arm Board Serial Terminal Set Up For a Linux machine a serial terminal such as Minicom can be used Minicom is a text based modem control and terminal emulation program for Unix like operating systems Gtkterm is a terminal e
13. ommand to copy the U Boot image to the SD MMC card For non padded U Boot image sudo dd if u boot imx of dev sdb bs 1k seek 1 For padded U Boot image sudo dd if u boot bin of dev sdb bs 1k seek 1 skip 1 The first 1 KB of the SD MMC card that includes the partition table will be preserved 6 7 Copying Kernel Image to SD Card Copy the kernel image to the SD MMC card sudo dd if ulmage of dev sdb bs 1M seek 1 This will copy ulmage to the media at offset 1 MB bs x seek 1 Mx 1 1MB MX6Q SABRESD U Boot gt mmc2 is current device MMC read dev 2 block 2048 count 8192 8192 blocks read OK Booting kernel from Legacy Image at 10800000 Image Name Linux 3 0 35 2666 gbdde708 Image Type ARM Linux Kernel Image uncompressed Data Size 3866444 Bytes 3 7 MB Load Address 10008000 Entry Point 10008000 Verifying Checksum OK Loading Kernel Image OK OK Starting kernel Uncompressing Linux done booting the kernel Fig 6 Kernel image in host system eISSN 2319 1163 pISSN 2321 7308 Fig 7 Linux boot process on Target board 4 penguins for quad core processor The boot time is an important factor It depends on the number of features supported by the board which extends size of the kernel and the filesystem The kernel boot with filesystem usually takes less than a minute 0 SaSu me Fig 8 Example filesystem linux ubuntu on target board 7 CONCLUSIONS
14. red old and Yocto is specifically preferred as Freescale is emphasizing on lighter and easier version Yocto is a dream project by Freescale Successful build of Yocto environment enables customization of kernel through which images of OS are built and they are ported to target platform Keywords ARM Bootloader BSP Customization Embedded Systems Filesystem Linux Ubuntu Porting OS SabreSD Yocto Build Environment 1 INTRODUCTION Linux has been available for the ARM architecture for many years now The original port was done by Russell King and he is still the maintainer through whom all ARM kernel patches generally pass 7 Linux is now the preferred operating system for many embedded devices mainly due to the efficient and portable design of the Linux kernel SABRE Board for Smart Devices Based on the i MX 6 Series Fig 1 Freescale SabreSD board courtesy Freescale Semiconductor Inc An Embedded system is application oriented special computer system which is accessible on both software and hardware It can satisfy the strict necessity of functionality consistency cost size and power consumption of the specific application With the extremely fast development of IC design and manufacture CPUs became inexpensive Lots of consumer electronics have embedded CPU and thus embedded systems became more popular For example Tablets point of sale devices industrial control panels or even your washing machine can
15. ronment install and run the Yocto and finally generate the output binary files to prepare the SD card bootable image compatibles The main objective of this paper is to make the Embedded Linux OS according to the target platform in this instance it is the I MX6 application processor platform which is developed by the Freescale Semiconductors The required components to build the OS are bootloader kernel and Filesystem Of course the development of the Operating System image individually by selecting the bootloader kernel and Filesystem but it is very tedious job to do such kind of selection as per time to market constraint vendors are developing the target image builders In this paper proposed building tool is the Yocto The Yocto project can be used to develop and deploy the Board Support Packages for various target platforms 3 1 Setting up the Host PC Requirements Ubuntu 12 04 32 64 bit OS version on host machine Volume 03 Issue 05 May 2014 Available http www ijret org 692 IJRET International Journal of Research in Engineering and Technology 100 gigabytes of free disk space for building images Note The Open Embedded build system should be able to run on any modern distribution that has the following versions for Git tar and Python e Git 1 7 5 or greater e tar 1 24 or greater e Python 2 7 3 or greater excluding Python 3 x which is not supported Packages sudo apt get install required package
16. s 3 2 Yocto Build Environment Latest Release The latest Yocto build can be installed locally on development system The user manual can be referred from Yocto reference manual 10 This manual explains how to set up build environment to configure and to compile 3 3 Configuration To fit the Embedded Linux on the hardware platform the configuration must be changed according to the type of application so that drivers must be included but default kernel configurations It also effects the boot time of the device In the kernel some of the configuration changes may required to the target device It depends on the application running on that device and it affects the final footprint of the binary image Here some of the configurations like in the Figure 5 in those some are Enable the loadable module support System type select imx233 Boot options This is the one of the significant configuration for example console ttySO 115200n8 For displaying log screen while booting the board with the baud rate of 115200 rootwait for detecting the devices asynchronously like USB or MMC rw mount root device read write on boot initrd to specify the location of the initial ramdisk rootfstype to select the type of root filesystem It depends on the target boot device if the device is an SD card it supports Extended filesystem ext2 or it may be the NAND flash it supports Journaling flash Filesystem jffs2 Icd_panel lms430 which s
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