Building Processor SDK 04.01.00.06 Yocto Morty BSP Distribution

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This document describes how Embedian builds a customized version of TI’s’s AM335X official Processor SDK 04.01.00.06 (Yocto Morty) BSP release for Embedian’s SMARC-T335X product platform. The approach is to pull from Embedian’s Github repository and build that using bitbake. The reason why we use this approach is that it allows co-development. The build output is comprised of binary images, feed packages, and an SDK for SMARC-T335X specific development.

TI makes their Processor-SDK-04.01.00.06 Arago build scripts available via the following GIT repository:

If you’re interested in TI’s overall Processor SDK build and test process you should analyze the following repository: 

It is this repository that actually pulls in the oe-layersetup project to perform the Linux Processor-SDK builds for TI’s entire suite of ARM Cortex-A chips. In this document we are only concerned with the oe-layersetup project.

Overview of the meta-embedian Yocto Layer

The supplied meta-embedian Yocto compliant layer has the following organization:

.
|-- conf
|   |-- layer.conf
|   |-- site.conf
|   |-- machine
|   |   `-- smarct335x.conf
|-- README
|-- recipes-bsp
|   |-- u-boot
|       |-- u-boot-smarc.inc
|       `-- u-boot-smarct335x_2017.01-smarct335x.bb
|-- recipes-core
|   |-- busybox
|       |-- busybox_1.23.1.bbappend
|       |   |-- busybox
|       |   |   `-- defconfig
|   |-- images
|   |   |-- meta-toolchain-smarc-tisdk.bb
|   |   |-- smarc-image.inc
|   |   |-- meta-toolchain-smarc-tisdk.inc
|   |   `-- smarct335x-rootfs-image.bb
|   `-- packagegroups
|       |-- packagegroup-smarc-console.bb
|       |-- packagegroup-smarc-tisdk-addons.bb
|       `-- packagegroup-smarct335x-sdk.bb
`-- recipes-kernel
|   |-- linux
|       |-- cmem.inc
|       |-- ti-uio.inc
|       |-- setup-defconfig.inc
|       |-- copy-defconfig.inc
|       |-- linux-smarct335x-staging_4.9.bb
|       `-- linux-smarct335x-staging-4.9
|       |   '-- defconfig
|   |-- files
|       |-- configs
|       |   '-- empty
|       |-- dra7xx
|       |   |-- am572x-pru-uio.dtsi
|       |   |-- cmem-dra71x.dtsi
|       |   |-- cmem.dtsi
|       |   |-- cmem-am571x.dtsi
|       |   '-- cmem-dra72x.dtsi
|       |-- k2e
|       |   |-- cmem.dtsi
|       |   '-- k2e-uio.dtsi
|       |-- k2g
|       |   '-- cmem.dtsi
|       |-- k2hk
|       |   |-- cmem.dtsi
|       |   '-- k2hk-uio.dtsi
|       |-- k2l-evm
|       |   |-- cmem.dtsi
|       |   '-- k2l-uio.dtsi
|       |-- keystone
|       |   '-- keystone-uio.dtsi
|       |-- ti33x
|       |   '-- am335x-pru-uio.dtsi
|       `-- ti43x
|       |   '-- am437x-pru-uio.dtsi
|   |-- linux-libc-headers
|       `-- cryptodev-module_%.bbappendd
|   `-- kselftests
|       |   '-- kselftests_4.9.bb

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Setting Up the Tools and Build Environment

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To build the latest TI  AM335X Processor-SDK-04.01.00.06, you first need an Ubuntu 14.04 LTS or 16.04 LTS installation. Because of support for 32-bit host is dropped as Linaro toolchain is available only for 64-bit machines., an x86_64 ubuntu 14.04 is highly recommended. Since bitbake does not accept building images using root privileges, please do not login as a root user when performing the instructions in this section. 

Once you have Ubuntu 14.04 LTS running, install the additional required support packages using the following console command:

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If you are using a 64-bit Linux, then you’d also need to install 32-bit support libraries, needed by the pre-built Linaro toolchain and other binary tools.

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You’ll also need to change the default shell to bash from Ubuntu’s default dash shell (select the <No> option):

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To build TI’s am335x Processor-SDK-04.01.00.06 you will need to install the Linaro arm compiler that TI used for the release:

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Add the following PATH definition to the .bashrc file in your $HOME directory:

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Next clone and intialize TI’s am335x SDK build process:

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Add the Embedian’s meta-embedian layer to the build process.

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Edit the ~/smarct3x-sdk-04.01.00.06/build/conf/bblayers.conf file to include the meta-embedian layer in the layer list. It should look something like this (the example reflects the absolute paths on my machine):

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Building the Target Platforms

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To build Embedian/TI Processor SDK BSP, use the following commands:

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Once it done, you can find all required images under ~/smarct3x-sdk-04.01.00.06/build/arago-tmp-external-linaro-toolchain/deploy/images/smarct335x/

You may want to build programs that aren’t installed into a root file system so you can make them available via a feed site (described below.) To do this you can build the package directly and then build the package named package-index to add the new package to the feed site.

The following example builds the minicom program and makes it available on the feed site:

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Once the build(s) are completed, you will find the resulting images, rpm and licenses in folder ~/smarct3x-sdk-04.01.00.06/build/arago-tmp-external-linaro-toolchain/deploy/

deploy/images/smarct335x/* 

This folder contains the binary images for the root file system and the Embedian SMARC-T335X specific version of the am335x SDK. Specifically the images are: 

deploy/images/smarct335x/u-boot.imx

This is u-boot binary file for SMARC-T335X.

deploy/images/smarct335x/MLO

The “Stage 1 Boot Loader” for SMARC-T335X.  Its purpose is load the Stage 2 Boot Loader (u-boot.img).

deploy/images/smarct335x/zImage

The kernel zImage for SMARC-T335X.  

deploy/images/smarct335x/zImage-am335x-smarct335x.dtb

The device tree binary file for SMARC-T335X. 

deploy/images/smarct335x/smarct335x-rootfs-image-smarct335x*

Embedian root file system images for software development on Embedian’s SMARC-T335X platforms.

deploy/ipk/*

This folder contains all the packages used to construct the root file system images. They are in opkg format (similar format to Debian packages) and can be dynamically installed on the target platform via a properly  constructed feed file. Here is an example of the feed file (named base-feeds.conf) that is used internally at Embedian to install upgrades onto a smarct335x platform without reflashing the file system:

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deploy/licenses/*

A database of all licenses used in all packages built for the system.

deploy/sdk/arago-2017.06-armv7a-linux-gnueabi-tisdk.sh

The installer for ARM toolchain that was created for the target platform. In Embedian’s case that means that the headers for the Boost libraries are baked into the tools. (Generate by meta-toolchain-smarc-tisdk image)

Setup SD Card

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For these instruction, we are assuming: DISK=/dev/mmcblk0, “lsblk” is very useful for determining the device id.

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Erase SD card:

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Create Partition Layout: Leave 1MB offset for boot file. With util-linux v2.26, sfdisk was rewritten and is now based on libfdisk.

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Create Partitions:

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Format Partitions:

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Mount Partitions:

On some systems, these partitions may be auto-mounted…

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Install Bootloader

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Copy MLO/u-boot.img to the boot partition

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Install uEnv.txt based bootscript

Create “uEnv.txt” boot script: ($ vim uEnv.txt)

Copy uEnv.txt to the boot partition:

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Install Linux Kernel zImage

Copy zImage to the boot partition:

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Install Linux Kernel Device Tree Binary

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Install Root Filesystem

Extract the Yocto built root filesystem to your SD card

Remove SD card:

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Shunt cross TEST# pin to ground and set the BOOT_SEL to ON OFF OFF. The module will boot up from SD card.  

Feed Packages

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You need to setup Apache2 web server on your development host machine first.

The Apache server default web page directory is /var/www/html .We need to populate it with a link pointing to our deb package repository.

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$ sudo ln -s /path/to/build/arago-tmp-external-linaro-toolchain/deploy/ipk /var/www/html/ipk

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The following procedure can be used on a Embedian SMARC-T335X device to download and utilize the feed file show above to install the tcpdump terminal emulation program:

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# vim /etc/apt/sources.list.d/yocto.list

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Only keep the following four lines.

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# vim /etc/opkg/base-feeds.conf

Only keep the following three lines:

src/gz all http://<ip address>/all
src/gz armv7ahf-neon http://<ip address>/armv7ahf-neon
src/gz smarct335x http://<ip address>/smarct335x

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# opkg update

# opkg upgrade

# opkg install tcpdump

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Writing Bitbake Recipes

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In order to package your application and include it in the root filesystem image, you must write a BitBake recipe for it.

When starting from scratch, it is easiest to learn by example from existing recipes. 

Example HelloWorld recipe using autotools

For software that uses autotools (./configure; make; make install), writing recipes can be very simple:

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DESCRIPTION = "Hello World Recipe using autotools"
HOMEPAGE = "http://www.embedian.com/"
SECTION = "console/utils"
PRIORITY = "optional"
LICENSE = "GPL"
PR = "r0"
  
SRC_URI = "git://github.com/embedian/helloworld-autotools.git;protocol=https"
S = "${WORKDIR}/git"
  
inherit autotools

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SRC_URI specifies the location to download the source from. It can take the form of any standard URL using http://, ftp://, etc. It can also fetch from SCM systems, such as git in the example above.

PR is the package revision variable. Any time a recipe is updated that should require the package to be rebuilt, this variable should be incremented.

inherit autotools brings in support for the package to be built using autotools, and thus no other instructions on how to compile and install the software are needed unless something needs to be customized.

S is the source directory variable. This specifies where the source code will exist after it is fetched from SRC_URI and unpacked. The default value is ${WORKDIR}/${PN}-${PV}, where PN is the package name and PV is the package version. Both PN and PV are set by default using the filename of the recipe, where the filename has the format PN_PV.bb.

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Example HelloWorld recipe using a single source file

This example shows a simple case of building a helloworld.c file directly using the default compiler (gcc). Since it isn’t using autotools or make, we have to tell BitBake how to build it explicitly.

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DESCRIPTION = "HelloWorld"
SECTION = "examples"
LICENSE = "GPL"
  
SRC_URI = "file://helloworld.c"
  
S = "${WORKDIR}"
  
do_compile() {
    ${CC} ${CFLAGS} ${LDFLAGS} helloworld.c -o helloworld
}
  
do_install() {
    install -d ${D}${bindir}
    install -m 0755 helloworld ${D}${bindir}
}

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In this case, SRC_URI specifies a file that must exist locally with the recipe. Since there is no code to download and unpack, we set S to WORKDIR since that is where helloworld.c will be copied to before it is built.

WORKDIR is located at ${OETREE}/build/arago-tmp-external-linaro-toolchain/work/armv7ahf-neon-linux-gnueabi/<package name and version for most packages. If the package is machine-specific (rather than generic for the armv8a architecture), it may be located in the smarct335x-linux-gnueabi subdirectory depending on your hardware (this applies to kernel packages, images, etc).

do_compile defines how to compile the source. In this case, we just call gcc directly. If it isn’t defined, do_compile runs make in the source directory by default.

do_install defines how to install the application. This example runs install to create a bin directory where the application will be copied to and then copies the application there with permissions set to 755.

D is the destination directory where the application is installed to before it is packaged.

${bindir} is the directory where most binary applications are installed, typically /usr/bin.

For a more in-depth explanation of BitBake recipes, syntax, and variables, see the Recipe Chapter of the OpenEmbedded User Manual.

Setup eMMC

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Setting up eMMC usually is the last step at development stage after the development work is done at your SD card or NFS environments. From software point of view, eMMC is nothing but a non-removable SD card on board. For SMARC-T335X, the SD card is always emulated as /dev/mmcblk1 and on-module eMMC is always emulated as /dev/mmcblk0. Setting up eMMC now is nothing but changing the device descriptor. 

This section gives a step-by-step procedure to setup eMMC flash. Users can write a shell script your own at production to simplify the steps.

First, we need to backup the final firmware from your SD card or NFS.

Prepare for eMMC binaries from SD card (or NFS):

Insert SD card into your Linux PC. For these instructions, we are assuming: DISK=/dev/mmcblk0, “lsblk” is very useful for determining the device id.

For these instruction, we are assuming: DISK=/dev/mmcblk0, “lsblk” is very useful for determining the device id.

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Mount Partitions:

On some systems, these partitions may be auto-mounted…

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for: DISK=/dev/mmcblk0

for: DISK=/dev/sdX

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Copy MLO to rootfs partition

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Copy u-boot.img to rootfs partition

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Copy zImage to rootfs partition

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Copy uEnv.txt to rootfs partition

Copy and paste the following contents to /media/rootfs/home/root ($ sudo vim /media/rootfs/home/root/uEnv.txt)

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Copy device tree binary to rootfs partition

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Copy final root file system to rootfs partition

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Remove SD card:

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Copy Binaries to eMMC from SD card

Insert this SD card into your SMARC-T335X device.

Now it will be almost the same as you did when setup your SD card, but the eMMC device descriptor is /dev/mmcblk0 now. Booting up the device from SD card (shunt cross TEST#).

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Erase eMMC:

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Create Partition Layout:

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Format Partitions:

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Mount Partitions:

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Copy binaries to boot partition

Copy uEnv.txt/Image/*.dtb to the boot partition

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Copy Linux kernel device tree binary

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Copy root file system to rootfs partition

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Unmount eMMC:

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Switch your Boot Select to eMMC (OFF ON ON) and you will be able to boot up from eMMC now.

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version 1.0a, 10/28/2024

Last updated 2024-10-28