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Overview
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mx35pdk (known als as mx35_3stack) is a development board by Freescale.
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It consists of three pluggable board:
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- CPU module, with CPU, RAM, flash
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- Personality board, with most interfaces (USB, Network,..)
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- Debug board with JTAG header.
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The board is usually delivered with redboot. This howto explains how to boot
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a linux kernel and how to replace the original bootloader with U-Boot.
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The board is delivered with Redboot on the NAND flash. It is possible to
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switch the boot device with the switches SW1-SW2 on the Personality board,
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and with SW5-SW10 on the Debug board.
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Delivered Redboot script to start the kernel
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---------------------------------------------------
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In redboot the following script is stored:
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fis load kernel
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exec -c "noinitrd console=ttymxc0,115200 root=/dev/mtdblock8 rw rootfstype=jffs2 ip=dhcp fec_mac=00:04:9F:00:E7:76"
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Kernel is taken from flash. The image is in zImage format.
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Booting from NET, rootfs on NFS:
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-----------------------------------
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To change the script in redboot:
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load -r -b 0x100000 <path_to_zImage>
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exec -c "noinitrd console=ttymxc0,115200 root=/dev/nfsroot rootfstype=nfsroot nfsroot=192.168.1.1:/opt/eldk-4.2-arm/armVFP rw ip=dhcp"
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If the ip address is not set, you can set it with :
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ip_address -l <board_ip/netmask> -h <server_ip>
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Linux partitions:
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---------------------------
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As default, the board is shipped with these partition tables for NAND
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and for NOR:
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Creating 5 MTD partitions on "NAND 2GiB 3,3V 8-bit":
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0x00000000-0x00100000 : "nand.bootloader"
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0x00100000-0x00600000 : "nand.kernel"
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0x00600000-0x06600000 : "nand.rootfs"
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0x06600000-0x06e00000 : "nand.configure"
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0x06e00000-0x80000000 : "nand.userfs"
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Creating 6 MTD partitions on "mxc_nor_flash.0":
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0x00000000-0x00080000 : "Bootloader"
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0x00080000-0x00480000 : "nor.Kernel"
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0x00480000-0x02280000 : "nor.userfs"
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0x02280000-0x03e80000 : "nor.rootfs"
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0x01fe0000-0x01fe3000 : "FIS directory"
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0x01fff000-0x04000000 : "Redboot config"
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NAND partitions can be recognized enabling in kernel CONFIG_MTD_REDBOOT_PARTS.
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For this board, CONFIG_MTD_REDBOOT_DIRECTORY_BLOCK should be set to 2.
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However, the setup in redboot is not correct and does not use the whole flash.
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Better solution is to use the kernel parameter mtdparts.
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Here the resulting script to be defined in RedBoot with fconfig:
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load -r -b 0x100000 sbabic/mx35pdk/zImage.2.6.37
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exec -c "noinitrd console=ttymxc0,115200 root=/dev/nfsroot rootfstype=nfsroot nfsroot=192.168.1.1:/opt/eldk-4.2-arm/arm rw ip=dhcp mtdparts=mxc_nand:1m(boot),5m(linux),96m(root),8m(cfg),1938m(user);physmap-flash.0:512k(b),4m(k),30m(u),28m(r)"
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Flashing U-Boot
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--------------------------------
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U-boot should be stored on the NOR flash.
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The boot storage can be select using the switches on the personality board
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(SW1-SW2) and on the DEBUG board (SW4-SW10).
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If something goes wrong flashing the bootloader, it is always possible to
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recover the board booting from the other device.
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Saving U-Boot in the NOR flash
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---------------------------------
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Check the partition for boot in the NOR flash. Setting the mtdparts as reported,
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the boot partition should be /dev/mtd0.
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Creating 6 MTD partitions on "mxc_nor_flash.0":
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0x00000000-0x00080000 : "Bootloader"
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0x00080000-0x00480000 : "nor.Kernel"
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0x00480000-0x02280000 : "nor.userfs"
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0x02280000-0x03e80000 : "nor.rootfs"
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0x01fe0000-0x01fe3000 : "FIS directory"
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0x01fff000-0x04000000 : "Redboot config"
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To erase the whole partition:
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$ flash_eraseall /dev/mtd0
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Writing u-boot:
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dd if=u-boot.bin of=/dev/mtd0
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To boot from NOR, you have to select the switches as follows:
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Personality board
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SW2 all off
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SW1 all off
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Debug Board:
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SW5 0
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SW6 0
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SW7 0
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SW8 1
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SW9 1
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SW10 0
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