Debian on the i.MX6 sabre sd platform in a few commands

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Debian on the i.MX6 sabre sd platform in a few commands

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Debian on the i.MX6 sabre sd platform in a few commands

debian-sabresd.png

Here we show how to bootstrap the Debian Linux distribution from a PC to the i.MX6 sabre sd platform.

While bootstrapping Debian on any architecture "natively" is pretty straightforward, "cross-bootstrapping" requires some techniques that we will explain.

This document assumes you are able to boot a Linux kernel on your platform already. See this post for details on how to do it. Also, this document assumes you are using a Debian PC for preparing your SD card. You will require the following packages to be installed:

  • binfmt-support
  • qemu-user-static
  • debootstrap

Note: all the commands found in the following steps need to be run as root.

Formatting the SD card

We need to format the SD card with two partitions; one small FAT partition to contain the Linux kernel and its dtb, and one large ext4 partition, which will contain the root filesystem with the Debian userspace. Also, we need to make sure we leave some space for u-boot starting from offset 1024B. Here is an example SD card layout:

  +-----+------+--------+-----+---------------+-----------------

  | MBR |  ... | u-boot | ... | FAT partition | Linux partition ...

  +-----+------+--------+-----+---------------+-----------------

  0     512    1024           1M              ~257M

(offsets in bytes)

Here is an example SD card layout, as displayed by fdisk:

  Device    Boot      Start         End      Blocks   Id  System

  /dev/sdc1            2048      526335      262144    c  W95 FAT32 (LBA)

  /dev/sdc2          526336     8054783     3764224   83  Linux

(units: 512B sectors)

You can format and mount the Linux partition with:

  # mkfs.ext4 /dev/<your-sd-card-second-partition>

  # mount /dev/<your-sd-card-second-partition> /mnt


Your SD card second partition is typically something in /dev/sd<X>2 or /dev/mmcblk<X>p2. Do not forget to install u-boot and a Linux kernel as explained in those posts.

Bootstrapping Debian

First stage


The first stage of Debian bootstrapping is done with:


  # debootstrap --foreign --arch=armhf testing /mnt


This will retrieve the base Debian packages from the internet, and perform a first stage of installation:

  I: Retrieving Release

  I: Retrieving Release.gpg

  I: Checking Release signature

  I: Valid Release signature (key id A1BD8E9D78F7FE5C3E65D8AF8B48AD6246925553)

  I: Validating Packages

  I: Resolving dependencies of required packages...

  I: Resolving dependencies of base packages...

  I: Found additional required dependencies: insserv libbz2-1.0 libcap2 libdb5.1 libsemanage-common libsemanage1 libslang2 libustr-1.0-1

  I: Found additional base dependencies: libee0 libept1.4.12 libestr0 libgcrypt11 libgnutls-openssl27 libgnutls26 libgpg-error0 libidn11 libjson-c2 liblognorm0 libmnl0 libnetfilter-acct1 libnfnetlink0 libp11-kit0 libsqlite3-0 libtasn1-3 libxapian22

  I: Checking component main on http://ftp.us.debian.org/debian...

  (...)

  I: Extracting util-linux...

  I: Extracting liblzma5...

  I: Extracting zlib1g...

At this point, the necessary tools for second stage of installation are under /mnt/debootstrap/.

Second stage

The second stage needs to run natively; on an arm platform, that is. But we can use the combination of two techniques to perform this stage on the PC anyway:


  # cp /usr/bin/qemu-arm-static /mnt/usr/bin/

  # chroot /mnt /debootstrap/debootstrap --second-stage


Those commands copy an arm emulator on the target filesystem, and use the chroot command to execute the second stage of the installation into the SD card, on the PC, with transparent emulation:

  I: Installing core packages...

  I: Unpacking required packages...

  I: Unpacking libacl1:armhf...

  I: Unpacking libattr1:armhf...

  I: Unpacking base-files...

  (...)

  I: Configuring tasksel...

  I: Configuring tasksel-data...

  I: Configuring libc-bin...

  I: Base system installed successfully.


You can now remove /mnt/usr/bin/qemu-arm-static, or keep it for later, subsequent chroot under emulation.


Finetuning the root filesystem


For development it is handy to remove the root password on the target by removing the '*' from /mnt/etc/shadow on the SD card:


  root::15880:0:99999:7:::


Also, we can add the following line in /mnt/etc/inittab to obtain a login prompt on the UART:


  T0:23:respawn:/sbin/getty -L ttymxc0 115200 vt100


You can now unmount the filesystem with:


  # umount /mnt


Boot!


Your SD card is ready for booting. Insert it in the SD card slot of your i.MX6 sabre sd platform, connect to the USB to UART port with a serial terminal set to 115200 baud, no parity, 8bit data and power up the platform.


At the time of writing u-boot tells the kernel to boot from the wrong partition by default, so we need to interrupt by pressing enter at u-boot prompt for the first boot and setup u-boot environment to fix this:


  U-Boot > setenv mmcroot /dev/mmcblk0p2 rootwait rw

  U-Boot > saveenv

  Saving Environment to MMC...

  Writing to MMC(1)... done

As this is saved in the SD card it need only to be done once at first boot. You can reboot your board or type boot; your Debian system should boot to a prompt:

  (...)

  [ ok ] Starting periodic command scheduler: cron.

  [ ok ] Running local boot scripts (/etc/rc.local).

  Debian GNU/Linux jessie/sid debian ttymxc0

  debian login:

From there you may login as root.

It is recommended to setup the network connection and install an ssh server inside the target for further development.

Enjoy!

See also...

  • With the amounts of memory we have today in the systems, it is even possible to boot Debian in a ramdisk. See this post about busybox for the ramdisk generation.
  • Another way of generating a root filesystem is by building it with buildroot. See and this post for details.
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Comments

如果想更换不同的版本,可以试试下面的命令

debootstrap --arch=armel --foreign wheezy debian_armel_wheezy_rootfs/ http://ftp.us.debian.org/debian

chroot ./debian_armel_wheezy_rootfs /debootstrap/debootstrap --second-stage

用root用户建立以目录rootfs_debian的根文件系统

在文件夹中rootfs_debian中构造debian文件系统

# apt-get install binfmt-support qemu-user-static debootstrap

#debootstrap --arch=armel --foreign wheezy rootfs_debian/ http://ftp.us.debian.org/debian

#cp /usr/bin/qemu-arm-static ./rootfs_debian/usr/bin/

#chroot ./rootfs_debian /debootstrap/debootstrap --second-stage

#rm rootfs_debian/usr/bin/qemu-arm-static

#vim rootfs_debian/etc/shadow

去掉root登录密码, 去掉'*'

root::15880:0:99999:7:::

添加串口支持

在文件rootfs_debian/etc/inittab 中添加

T0:23:respawn:/sbin/getty -L ttymxc0 115200 vt100

添加更新包的源/etc/apt/sources.list

deb http://ftp.us.debian.org/debian wheezy main


Hello Vincent, link https://community.freescale.com/docs/DOC-99218 to generating a root filesystem by building it with buildroot is restricted. Can you please check and "unrestrict" it?

Hi DraganOstojic, thanks for pointing this out. This should be fixed now; sorry for the inconvenience.

Hi Vincent Stehle

This is Saida i recently purchased I.MX6DLSabreSD board.

i want to port u-boot to this board (sdcard booting)

most posts i hvae seen are related to Quad board only

i tried u-boot-2013-rc1.tar but its not booting may be this for quad

can you tell me which u-boot version supports for dual lite board

and also kernel posting steps

till now i have done with arm-none-eabi cross compiler tools

1 make mx6dsabredsd_config and cross compilation with above tool

2 dd if=u-boot.imx of=/dev/sdc1 bs=1k seek=1

3 sync

guide me if i did any mistakes

thank you in advance

This set of howtos is really awful and got me very fast a running system. Thank you very much.

But it only gives me command line.

I already tried to install xorg and kde-standard, but this gives me only a login-screen which crashes, when I try to login.

Obviously I have no graphics-driver or I'm missing some other configurations/files.

Is there a (simple) howto or tutorial to also set up a X-System with graphical desktop?

Hi steffendoster​,

You might be interested in Buildroot then, as it allows to build x11 fairly easily.

If you want some hints for buildroot on i.MX6, we have this post on the matter: Buildroot for the i.MX6 sabre sd platform in a few commands. From there, adding x11 might be as simple as selecting the necessary packages with make menuconfig.

Best regards,

V.

Dear Vincent and other friends here,

     Thanks so much for the help with installing debian on this  i.MX6 sabre sd board.  Following the instructions here,  I was able to have a debian system running on it.  But there is one kernel module missing, which is the cpurfreq kernel module.

   This module is very important for me,since I would like to measure the computational speed of our algorithm at certain clock frequencies. 

   Can you confirm whether or not you are having this module in your built system ?  

[ ok ] Loading cpufreq kernel modules...done (none).

[ ok ] CPUFreq Utilities: Setting ondemand CPUFreq governor...disabled, governor not available...done.

Hi @Vincent Stehle ,

Thanks for your helpful doc!

I am using the Debian 8 jessi(16.04) which has no /etc/inittab now.

So how can I obtain a login prompt on the UART??

All the Best

Kane

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